WO2019011107A1 - 网络切换方法及装置 - Google Patents

网络切换方法及装置 Download PDF

Info

Publication number
WO2019011107A1
WO2019011107A1 PCT/CN2018/091759 CN2018091759W WO2019011107A1 WO 2019011107 A1 WO2019011107 A1 WO 2019011107A1 CN 2018091759 W CN2018091759 W CN 2018091759W WO 2019011107 A1 WO2019011107 A1 WO 2019011107A1
Authority
WO
WIPO (PCT)
Prior art keywords
network
terminal device
voice service
information
user plane
Prior art date
Application number
PCT/CN2018/091759
Other languages
English (en)
French (fr)
Inventor
崇卫微
吴晓波
辛阳
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN201710693995.8A external-priority patent/CN109257779A/zh
Priority to BR112019000557-9A priority Critical patent/BR112019000557A2/pt
Priority to ES18815923T priority patent/ES2862404T3/es
Priority to KR1020197002390A priority patent/KR102198411B1/ko
Priority to JP2019500561A priority patent/JP6724235B2/ja
Priority to EP18815923.0A priority patent/EP3462776B1/en
Priority to RU2019105002A priority patent/RU2717839C1/ru
Priority to CN201880046927.5A priority patent/CN110945903B/zh
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to AU2018298508A priority patent/AU2018298508B2/en
Priority to EP20203815.4A priority patent/EP3833103B1/en
Priority to MYPI2018002725A priority patent/MY201248A/en
Priority to US16/198,219 priority patent/US10939345B2/en
Publication of WO2019011107A1 publication Critical patent/WO2019011107A1/zh
Priority to AU2020244393A priority patent/AU2020244393B2/en
Priority to US17/085,714 priority patent/US11323933B2/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/50—Network services
    • H04L67/56—Provisioning of proxy services
    • H04L67/59—Providing operational support to end devices by off-loading in the network or by emulation, e.g. when they are unavailable
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/16—Performing reselection for specific purposes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/14—Session management
    • H04L67/141—Setup of application sessions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0022—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies
    • H04W36/00224—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]
    • H04W36/00226—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB] wherein the core network technologies comprise IP multimedia system [IMS], e.g. single radio voice call continuity [SRVCC]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface
    • H04W36/144—Reselecting a network or an air interface over a different radio air interface technology
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/12—Setup of transport tunnels

Definitions

  • the present application relates to the field of communications technologies, and in particular, to a network switching method and apparatus.
  • IMS Internet Protocol Multimedia Subsystem
  • the embodiment of the present invention provides a network switching method and device, which are used to solve the problem that a terminal device cannot perform an IMS voice service.
  • the embodiment of the present application provides the following technical solutions:
  • the first aspect provides a network switching method, including: a first access network device receives first session management information from a session management network element, where the first session management information is used to request to establish a user plane for a voice service of the terminal device. a first access network device sends a handover request to the first mobility management network element according to the first session management information and the first condition, where the handover request is used to switch the terminal device from the first network to the second network, the first condition Including: The first network cannot perform voice services.
  • the terminal device when the terminal device in the first network performs the voice service, the terminal device can be switched to the second network, so that the terminal device can perform the voice service on the second network, and the first network is solved.
  • the terminal device cannot perform the problem of voice service.
  • the first condition further includes: the second network supports the voice service, the signal quality of the second network satisfies the voice service requirement, and the network device of the first network, and the terminal device supports the first network and the second network. At least one of the switches.
  • the method further includes: the first access network device sends the second session management information to the session management network element, where the second session management information includes information that the establishment of the user plane tunnel of the voice service is accepted.
  • the network element in the first network establishes a user plane tunnel for the voice service of the terminal device.
  • the method before the first access network device sends the second session management information to the session management network element, the method further includes: determining, by the first access network device, the first session management information and the first condition Wireless resources are not allocated for user plane tunnels of voice services.
  • the network element in the first network establishes a user plane tunnel for the voice service of the terminal device.
  • the method further includes: the first access network device sends third session management information to the session management network element, where the third session management information includes information that the establishment of the user plane tunnel of the voice service is rejected.
  • the network element in the second network establishes a user plane tunnel for the voice service of the terminal device.
  • the information that the establishment of the user plane tunnel of the voice service is rejected includes the reason information of the rejection.
  • the network element in the second network establishes a user plane tunnel for the voice service of the terminal device.
  • the cause information is that the terminal device is performing the handover procedure.
  • the network element in the second network establishes a user plane tunnel for the voice service of the terminal device.
  • the first condition further includes: the second network is unable to perform the voice service
  • the method further includes: the first access network device sends the fourth session management information to the session management network element, and the fourth session management information
  • the information about the establishment of the user plane tunnel including the voice service is rejected, and the information about the establishment of the user plane tunnel of the voice service is rejected, including insufficient radio resources.
  • the network element in the second network does not establish a user plane tunnel for the voice service of the terminal device.
  • the second aspect provides a network switching method, including: the session management network element receives the third session management information sent by the first access network device, and the third session management information includes the establishment of the user plane tunnel of the voice service of the terminal device. The rejected reason information; the session management network element determines that the terminal device switches from the first network to the second network; the session management network element establishes a user plane tunnel for the voice service in the second network according to the cause information.
  • the second aspect provides a method, when the terminal device in the first network switches from the first network to the second network, the session management network element establishes a user plane tunnel for the voice service in the second network according to the cause information, if the second network can perform In the voice service, the user plane tunnel can be successfully established, so that the terminal device can perform the voice service in the second network, and solve the problem that the terminal device in the first network cannot perform the voice service.
  • the cause information is that the terminal device is performing the handover procedure.
  • the session management network element establishes a user plane tunnel for the voice service in the second network according to the cause information, including: the session management network element is in the first preset time period according to the reason information and the second condition.
  • the second network establishes a user plane tunnel for the voice service, and the second condition includes that the second network cannot perform the voice service.
  • the possible design provides a first preset time period for the terminal device to complete the joint registration. By setting the first preset time period reasonably, the terminal device can initiate the CSFB call after completing the joint registration. Thereby ensuring that the terminal device successfully initiates a CSFB call.
  • the session management network element establishes a user plane tunnel for the voice service in the second network after the first preset time period according to the reason information and the second condition, including: the session management network element according to the reason information and the The second condition sends a tunnel establishment request to the serving gateway of the second network after the first preset time period, and the tunnel establishment request is used to request the user plane tunnel for establishing the voice service.
  • the session management network element establishes a user plane tunnel for the voice service in the second network after the first preset time period according to the reason information and the second condition, including: the session management network element according to the cause information
  • the service gateway of the second network sends a tunnel establishment request, and the tunnel establishment request is used to request to establish a voice service user plane tunnel; the session management network element receives the tunnel establishment response sent by the service gateway, and the tunnel establishment response includes the user plane tunnel establishment of the voice service.
  • the rejected information is sent by the session management network element to the policy function control network element after the first preset time period according to the second condition, where the first message is used to indicate that the user plane tunnel establishment of the voice service fails.
  • the third aspect provides a network switching method, including: a second mobility management network element receives a tunnel establishment request sent by a serving gateway, and a tunnel establishment request is used to request a user plane tunnel for establishing a voice service for the terminal device; The mobility management network element sends a tunnel establishment response to the serving gateway according to the second condition, where the tunnel establishment response includes the user plane tunnel establishment denied information of the voice service of the terminal device, and the second condition includes that the second network cannot perform the voice service.
  • the second mobility management network element sends a tunnel establishment response to the serving gateway when the second network cannot perform the voice service, so that the service gateway transmits the rejected information of the user plane tunnel establishment to the IMS network, thereby
  • the IMS network can be triggered to trigger the CSFB service of the terminal device, thereby enabling the terminal device to perform the CS voice service.
  • the second condition further includes: the terminal device is a terminal device that switches from the first network to the second network.
  • the method before the second mobility management network element sends a tunnel establishment response to the serving gateway according to the second condition, the method further includes: determining, by the second mobility management network element, that the terminal device completes the joint registration. This possible design ensures that the terminal device successfully initiates a CSFB call.
  • the second mobility management network element determines that the terminal device completes the joint registration, and includes: the second mobility management network element determines to receive the joint registration completion message from the terminal device.
  • a fourth aspect provides a network switching method, including: a second mobility management network element sends a wireless tunnel establishment request to a second access network device, where the wireless tunnel establishment request is used to request to establish a user plane for the voice service of the terminal device.
  • the second mobility management network element receives the wireless tunnel establishment response sent by the second access network device, and the wireless tunnel establishment response includes the user plane tunnel establishment denied information of the voice service of the terminal device; the second mobility management network element
  • the tunnel establishment response is sent to the serving gateway according to the second condition, where the tunnel establishment response includes the user plane tunnel establishment denied information of the voice service of the terminal device, and the second condition includes that the second network cannot perform the voice service.
  • the second mobility management network element sends the denied information of the user plane tunnel establishment to the serving gateway, so that the serving gateway transmits the rejected information of the user plane tunnel establishment to the IMS network, thereby enabling the IMS to
  • the network triggers the CSFB service of the terminal device, and the terminal device performs the CS voice service.
  • the second condition further includes: the terminal device is a terminal device that switches from the first network to the second network.
  • the second mobility management network element sends a tunnel establishment response to the serving gateway according to the second condition, including: the second mobility management network element determines that the second condition is established and the terminal device completes the joint registration; The mobility management network element sends a tunnel establishment response to the serving gateway.
  • the second mobility management network element determines that the terminal device completes the joint registration, and includes: the second mobility management network element determines to receive the registration completion message from the terminal device.
  • the fifth aspect provides a network switching method, including: a second mobility management network element receives a tunnel establishment request sent by a serving gateway, where the tunnel establishment request is used to request a user plane tunnel for establishing a voice service for the user equipment terminal device;
  • the second condition is established, the second mobility management network element determines that the terminal device completes the joint registration, the second condition includes that the second network cannot perform the voice service; and the second mobility management network element sends the wireless tunnel establishment request to the second access network device.
  • the wireless tunnel establishment request is used to request to establish a user plane tunnel for the voice service of the terminal device; the second mobility management network element receives the wireless tunnel establishment response sent by the second access network device, and the wireless tunnel establishment response includes the voice service of the terminal device.
  • the user plane tunnel establishes the rejected information; the second mobility management network element sends a tunnel establishment response to the serving gateway according to the wireless tunnel establishment response, and the tunnel establishment response includes the information that the user plane tunnel establishment of the voice service of the terminal device is rejected.
  • the second mobility management network element determines that the terminal device completes the joint registration, and sends the denied information of the user plane tunnel establishment to the service gateway, so that the service gateway transmits the rejected information of the user plane tunnel establishment to the
  • the IMS network can enable the IMS network to trigger the CSFB service of the terminal device, thereby enabling the terminal device to perform the CS voice service, and also ensure that the terminal device successfully initiates the CSFB call.
  • the second condition further includes: the terminal device is a terminal device that switches from the first network to the second network.
  • the second mobility management network element determines that the terminal device completes the joint registration, and the second mobility management network element determines that the registration completion message sent by the terminal device is received.
  • the sixth aspect provides a network switching method, including: receiving, by a second access network device, a wireless tunnel establishment request sent by a second mobility management network element, where the wireless tunnel establishment request is used to request the second access network device to be a terminal
  • the device establishes a user plane tunnel of the voice service; the second access network device sends a wireless tunnel establishment response to the second mobility management network element according to the second condition, where the wireless tunnel establishment response includes the user plane tunnel establishment denied information of the voice service,
  • the second condition includes the second network being unable to perform voice service.
  • the second access network device refuses to allocate a radio resource to the user plane tunnel when the second network cannot perform the voice service, and carries the rejected information of the user plane tunnel establishment of the voice service in the wireless tunnel establishment response.
  • the medium mobility management network element sends the second mobility management network element, and the second mobility management network element can transmit the rejected information of the user plane tunnel establishment to the IMS network, so that the IMS network triggers the CSFB service of the terminal device, and the terminal device performs the CS. Voice business.
  • the second condition further includes: the terminal device is a terminal device that switches from the first network to the second network.
  • the seventh aspect provides a network switching method, including: receiving, by the IMS network element, a request message for the terminal device to establish a voice service in the PS domain; and determining, by the IMS network element, that the voice service cannot be established in the PS domain of the first network or the second network.
  • the IMS network element determines that the terminal device completes the joint registration; the IMS network element triggers the CSFB service of the terminal device.
  • the IMS network element triggers the CSFB service of the terminal device when it is determined that the voice service cannot be established in the PS domain of the first network or the second network, and the terminal device completes the joint registration, because the terminal device completes the joint registration
  • the terminal device initiates a CSFB call. Therefore, the method provided by the seventh aspect can also ensure that the terminal device successfully initiates the CSFB call, thereby enabling the terminal device to perform the CS voice service.
  • the method further includes: determining, by the IMS network element, that the terminal device is registered in the first network.
  • the IMS network element determines that the voice service cannot be established in the PS domain of the first network or the second network, including: the IMS network element acquires voice service establishment failure information from the PS domain of the first network; or, IMS The network element acquires voice service establishment failure information from the PS domain of the second network.
  • the IMS network element determines that the terminal device completes the joint registration, including: the IMS network element determines that the second preset time period after the voice service cannot be established in the PS domain of the first network or the second network, the IMS The network element determines that the terminal device completes the joint registration; or the IMS network element determines that the terminal device completes the joint registration according to the registration location information of the terminal device obtained from the policy control network element or the home user server.
  • the terminal device is a calling terminal device of the voice service
  • the IMS network element triggers the CSFB service of the terminal device, including: the IMS network element sends a second message to the calling terminal device, and the second message is used to trigger The calling terminal device initiates a CSFB calling service.
  • the terminal device is the called terminal device of the voice service
  • the IMS network element triggers the CSFB service of the terminal device, including: the IMS network element sends a third message to the called domain selection device, and the third message is used for Indicates that the called voice service establishment of the PS domain of the first network or the second network fails, so that the called domain selection device triggers the CSFB called voice service of the called terminal device.
  • the eighth aspect provides a network switching method, including: a second mobility management network element receives a fourth message sent by the first mobility management network element, where the fourth message is used to confirm that the terminal device completes relocation; and the second mobile The mobility management network element sends a tunnel modification request to the serving gateway according to the second condition, where the tunnel modification request is used to modify the signaling plane tunnel information of the voice service of the terminal device, and the second condition includes that the second network cannot perform the voice service.
  • the second mobility management network element when the second network is unable to perform the voice service, the second mobility management network element sends a tunnel modification request to the service gateway, and the service gateway forwards the tunnel modification request to the session management network element, because the session management network After receiving the tunnel modification request, the UE sends a message for triggering the terminal device to initiate the CSFB call (ie, the second message below) to the terminal device. Therefore, the method provided by the eighth aspect cannot be performed on the second network.
  • the terminal device is triggered to initiate a CSFB call, so that the terminal device performs the CS voice service.
  • the second mobility management network element sends a tunnel modification request to the serving gateway according to the second condition, including: the second mobility management network element determines that the second condition is established and the UE completes the joint registration; the second mobile The sexual management network element sends a tunnel modification request to the serving gateway.
  • a ninth aspect provides a network registration method, the method comprising: a first mobility management network element receiving a registration request from a terminal device, the registration request for requesting to register the terminal device with the first network; if the third condition is established, The first mobility management network element sends the first indication information to the terminal device, where the first indication information is used to indicate that the voice service of the PS domain is supported, and the third condition includes: the first network supports moving the terminal device to the second network.
  • the ninth aspect provides the method, whether the first network supports the voice service of the terminal device, whether the first network has the capability of dropping the terminal device to the network capable of providing the voice service by using a handover or other manner when the terminal device initiates the voice service.
  • the first mobility management network element When the terminal device registers with the first network, the first mobility management network element indicates that the voice service of the PS domain of the terminal device is supported, thereby ensuring that the terminal device registers and resides in the first network without reselecting to other devices.
  • the network saves network resources and ensures that the terminal device performs the PS domain voice service registration process and initiates the PS domain voice call process through the first network.
  • the core network of the first network and the second network are the same, and the access systems are different; or the core network and the access system of the first network and the second network are different.
  • the first network supports moving the terminal device to the second network, including: the first access network device in the first network supports receiving the first session management information from the session management network element.
  • the terminal device is connected to the second network, and the first session management information is used to request to establish a user plane tunnel for the voice service of the terminal device.
  • the third condition further includes: supporting handover interoperation between the first network and the second network, and the second network is capable of supporting at least one of voice services of the PS domain.
  • the switching interoperation is supported between the first network and the second network, including: a handover interoperation interface exists between the first network and the second network.
  • the method before the first mobility management network element sends the first indication information to the terminal device, the method further includes: determining, by the first mobility management network element, that the terminal device is a terminal mainly based on the voice service device. Since the terminal device based on the data service is independent of the voice service, the optional method can distinguish the terminal type, and the terminal device that is mainly based on the data service does not need to implement the solution, that is, it is not required to determine whether the third condition is established. There is also no need to send the first indication information.
  • the registration request carries the terminal device as the indication information of the terminal device that is mainly based on the voice service
  • the first mobility management network element determines that the terminal device is the terminal device that is mainly based on the voice service, including:
  • a mobility management network element determines, according to the registration request, that the terminal device is a terminal device that is mainly based on voice services.
  • the method before the first mobility management network element sends the first indication information to the terminal device, the method further includes: determining, by the first mobility management network element, that the terminal device supports the voice service initiation process from the first A network moves to the second network and continues the initiation process of the voice service through the second network. Since only the terminal device supports the process of moving the voice service from the first network to the second network and continuing the voice service through the second network, the method provided by the first aspect can be implemented, and therefore, the method can be determined in advance. This information avoids affecting terminal devices that cannot support the process of initiating a voice service from the first network to the second network during the voice service initiation process and continuing the voice service through the second network.
  • the registration request further carries indication information that the terminal device supports the process of starting the voice service from the first network to the second network and continuing the voice service through the second network, the first mobility.
  • the management network element determines that the terminal device supports the process of initiating the voice service from the first network to the second network in the voice service initiation process, and the first mobility management network element determines the terminal device support according to the registration request.
  • the voice service is initiated from the first network to the second network and the voice service initiation process is continued through the second network.
  • a network registration method includes: the terminal device generates a registration request, where the registration request is used to request to register the terminal device with the first network, and the registration request carries the terminal device as a terminal mainly based on the voice service.
  • the indication information of the device the terminal device sends a registration request to the first mobility management network element.
  • the registration request further includes indication information that the terminal device supports the process of starting the voice service from the first network to the second network and continuing the voice service through the second network during the voice service initiation process.
  • the core network of the first network and the second network are the same, and the access systems are different; or the core network and the access system of the first network and the second network are different.
  • a network device may be a first access network device, a session management network element, a second mobility management network element, a second access network device, an IMS network element, or a first a mobility management network element, when the network device is a first access network device, the network device has a function of implementing any one of the methods provided by the first aspect; when the network device is a session management network element, the network device Having the function of implementing any one of the methods provided by the second aspect; when the network device is the second mobility management network element, the network device has the third aspect, the fourth aspect, the fifth aspect, or the eighth aspect provided The function of any one of the methods; when the network device is a second access network device, the network device has the function of implementing any one of the methods provided by the sixth aspect; when the network device is an IMS network element, the network device Having the function of implementing any one of the methods provided by the seventh aspect; when the network device is the first mobility management network element, the network device has any one
  • a terminal device has the function of implementing any one of the methods provided by the tenth aspect, and the function implemented by the terminal device may be implemented by using hardware or by executing corresponding software by hardware.
  • the hardware or software includes one or more functional units corresponding to the methods provided by the tenth aspect.
  • a thirteenth aspect provides a network device, including: a memory, a processor, and a communication interface; the memory is configured to store a computer to execute an instruction, the processor executes a computer-executed instruction of the memory storage, and causes the network device to implement the foregoing aspect through a communication interface
  • the network device may be a first access network device, a session management network element, a second mobility management network element, a second access network device, an IMS network element, or a first mobility management network element.
  • the network device may implement any one of the methods provided by the first aspect; when the network device is a session management network element, the network device may implement the second aspect Any one of the methods provided by the third aspect, the fourth aspect, the fifth aspect, or the eighth aspect; when the network device is the second mobility management network element; When the second access network device is the second access network device, the network device can implement any one of the methods provided by the sixth aspect; when the network device is an IMS network element The network device may implement any one of the methods provided by the seventh aspect; when the network device is the first mobility management network element, the network device has the function of implementing any one of the methods provided by the ninth aspect.
  • a terminal device includes: a memory, a processor, and a communication interface; the memory is configured to store a computer to execute an instruction, the processor executes a computer-executed instruction stored in the memory, and the terminal device implements the tenth through the communication interface. Any of the methods provided by the aspect.
  • a computer readable storage medium comprising instructions that, when executed on a computer, cause the computer to perform any of the methods provided by the first aspect.
  • a computer readable storage medium comprising instructions that, when executed on a computer, cause the computer to perform any of the methods provided by the second aspect.
  • a computer readable storage medium comprising instructions that, when executed on a computer, cause the computer to perform any of the methods provided by the third aspect.
  • a computer readable storage medium comprising instructions that, when executed on a computer, cause the computer to perform any of the methods provided by the fourth aspect.
  • a computer readable storage medium comprising instructions that, when run on a computer, cause the computer to perform any of the methods provided by the fifth aspect.
  • a computer readable storage medium comprising instructions that, when run on a computer, cause the computer to perform any of the methods provided by the sixth aspect.
  • a computer readable storage medium comprising instructions that, when run on a computer, cause the computer to perform any of the methods provided by the seventh aspect.
  • a twenty-second aspect a computer readable storage medium comprising instructions that, when run on a computer, cause the computer to perform any of the methods provided by the eighth aspect.
  • a computer readable storage medium comprising instructions that, when executed on a computer, cause the computer to perform any of the methods provided by the ninth aspect.
  • a computer readable storage medium comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the tenth aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the first aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the second aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the third aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the fourth aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the fifth aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the sixth aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the seventh aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the eighth aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the ninth aspect.
  • a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods provided by the tenth aspect.
  • FIG. 1 is a schematic structural diagram of a 5G network according to an embodiment of the present application.
  • FIG. 1A is a schematic diagram of a terminal device accessing a 5G CN according to an embodiment of the present disclosure
  • FIG. 2 is a schematic structural diagram of an EPS network according to an embodiment of the present application.
  • FIG. 3 is a schematic diagram of a network architecture after a 5G network and an EPS network are integrated according to an embodiment of the present application;
  • FIG. 4 is a schematic diagram of communication between an EPS network and an IMS network according to an embodiment of the present application
  • FIG. 5 is a schematic diagram of performing IMS voice communication between terminal devices according to an embodiment of the present disclosure
  • FIG. 6 is a schematic structural diagram of a network device according to an embodiment of the present application.
  • FIG. 6 is a schematic structural diagram of a terminal device according to an embodiment of the present application.
  • FIG. 7 is an interaction flowchart of a network switching method according to an embodiment of the present application.
  • FIG. 8 and FIG. 9 are flowcharts of a process for network switching according to an embodiment of the present application.
  • FIG. 10 is a schematic diagram of a process for establishing a user plane tunnel according to an embodiment of the present application.
  • FIG. 13 is a schematic diagram of a method for ensuring that a terminal device successfully initiates a CSFB call according to an embodiment of the present disclosure
  • FIG. 28 are respectively an interaction flowchart of a network switching method according to an embodiment of the present application.
  • 28A is a flowchart of a network registration method according to an embodiment of the present application.
  • 28B is a flowchart of still another network registration method according to an embodiment of the present application.
  • FIG. 29 is a schematic diagram of a network device according to an embodiment of the present disclosure.
  • FIG. 29 is a schematic diagram of a terminal device according to an embodiment of the present application.
  • the method provided by the embodiment of the present application can be applied to a wireless communication system, for example, a global system of mobile communication (GSM) system, a code division multiple access (CDMA) system, and a wideband code division.
  • GSM global system of mobile communication
  • CDMA code division multiple access
  • WCDMA Wideband code division multiple access wireless
  • GPRS general packet radio service
  • UMTS universal mobile melecommunications system
  • the method provided by the embodiment of the present application can be applied to the 5G network shown in FIG. 1 .
  • the 5G network may include: an authentication server function (AUSF) network element, and access And mobility management function (AMF) network element, data network (DN), unified data management (UDM) network element, policy control function (PCF) Network element, (radio) access network (radio access network) device, user plane function (UPF) network element, terminal device, application function (AF) Network element, session management function (SMF) network element.
  • AUSF authentication server function
  • AMF access And mobility management function
  • DN data network
  • UDM unified data management
  • PCF policy control function
  • radio radio access network
  • UPF user plane function
  • AF application function
  • SMF session management function
  • the (R) AN device of the 5G network may be a next generation (NG) RAN device, or may be an evolved universal terrestrial radio access network (E-UTRAN) device.
  • the 5G network can be connected to the above two access network devices at the same time, that is, the 5G network may have two different radio access types (RATs) at the same time.
  • the terminal device can access the 5G core network (CN) through the E-UTRAN device or the NG RAN device.
  • the terminal device registers with the 5G network through the NG RAN and accesses the system in the NG RAN.
  • the method provided by the embodiment of the present application is exemplified by taking the voice service as an example.
  • the control plane (CP) function network element includes: a UDM network element, an AUSF network element, a PCF network element, an AMF network element, and an SMF network element.
  • the main functions of the (R) AN device include: providing a wireless connection;
  • the main functions of the UPF network element include: routing and forwarding data packets, mobility anchors, and uplink classifiers to support routing service flows to DN and BP to support multiple A packet data unit (PDU) session, etc.;
  • the DN can serve an operator, an Internet access, or a third-party service;
  • the main functions of the AMF network element include management user registration, reachability detection, selection of SMF nodes, Mobile state transition management, etc.;
  • SMF network element main functions include: control session establishment, modification and deletion, user plane node selection, etc.;
  • PCF network element main functions include: policy decision point, providing service data flow and application detection, Control, quality of service (QoS) and flow-based charging control rules;
  • AF network element main functions include: interaction with the 3rd generation partnership project (3GPP) core network to provide Service, to affect service flow routing, access network capability opening, policy control, etc.;
  • the terminal device may also be referred to as user equipment (UE), access terminal, subscriber unit, subscriber station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, and wireless communication.
  • Device user agent, or user device.
  • the terminal device may also be a station (station, ST for short) in a wireless local area network (WLAN), which may be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, or a wireless local ring.
  • WLAN wireless local area network
  • WLL wireless local loop
  • PDA personal digital assistant
  • handheld device with wireless communication function computing device or other processing device connected to wireless modem
  • in-vehicle device wearable device (Also known as wearable smart devices).
  • the terminal device may also be a terminal device in a next-generation communication system, for example, a terminal device in 5G or a terminal device in a public land mobile network (PLMN) in the future, new radio (referred to as new radio) NR) Terminal equipment and the like in the communication system.
  • a terminal device in 5G or a terminal device in a public land mobile network (PLMN) in the future, new radio (referred to as new radio) NR) Terminal equipment and the like in the communication system.
  • PLMN public land mobile network
  • new radio referred to as new radio
  • the method provided by the embodiment of the present application can also be applied to an evolved packet system (EPS) network (that is, a so-called 4G network) shown in FIG. 2, as shown in FIG. 2, the EPS network.
  • EPS evolved packet system
  • the following may include a plurality of functional network elements: a terminal device, an E-UTRAN (specifically, an eNodeB), a serving gateway (SGW), a packet data network gateway (PGW), and a mobility management network.
  • HSS home subscriber server
  • MSC mobile switching center
  • PCRF policy and charging rules function
  • the functional network elements in the 5G network and the functional network elements in the EPS network can be integrated, so that the 5G network and the EPS network can interact, see FIG. 3, after integration.
  • the functional network elements in the network include: HSS+UDM functional network elements (refers to functional network elements that have both HSS functions and UDM functions), and PCF+PCRF functional network elements (refers to both PCF functions and PCRFs).
  • SMF+PGW-C function network element refers to the function of the SMF and the packet data network gateway-control plane (PGW-C)) Functional network element
  • UPF+PGW-U function network element refers to the functional network element that has the functions of the UPF and the packet data network gateway-user plane (PGW-U))
  • SGW MME, E-UTRAN, AMF, NGRAN, and terminal equipment.
  • HSS+UDM function network element, the PCF+PCRF function network element, the SMF+PGW-C function network element, and the UPF+PGW-U are merely examples, and each network element may also be Two network elements separated from each other are not limited herein.
  • the more mature voice service solutions include the IMS voice service solution in the EPS network and the circuit switching (CS) voice service solution in the 2G/3G network.
  • the 5G network does not support the IMS and the CS voice service.
  • the embodiment of the present application provides a network switching method, so that the terminal device can switch from the 5G network to the EPS network or the 2G/3G network when the voice service needs to be performed. Conduct voice services.
  • the communication diagram of the EPS network and the IMS network may be referred to FIG. 4, where the IMS network includes: Proxy-Call Session Control Funtion (referred to as Proxy-Call Session Control Funtion, referred to as P-CSCF)/Session Border Control (SBC), interrogating-call session control funence (I-CSCF)/serving call control control (serving-call session control funtion, short for short) S-CSCF), telephony application server (TAS) and IMS media gateway (IMS MGW), wherein the terminating access domain selection (T-ADS) It is included in the TAS, so the called domain selection device below can be considered as a TAS.
  • the TAS can also be a service centralization and continuity application server (SCC AS).
  • SCC AS service centralization and continuity application server
  • the process of the communication between the calling terminal device and the called terminal device may be referred to FIG. 5, which specifically includes: the calling terminal device sends the call-related information to the calling access network, and The call related information arrives at the called terminal device after the calling access network, the calling core network, the calling IMS network, the called IMS network, the called core network, and the called access network, and the called terminal device calls the calling terminal.
  • the information fed back by the terminal device can be sent in the opposite direction.
  • a hardware structure diagram of a network device 60 includes at least one processor 601, a communication bus 602, a memory 603, and at least one communication interface 604.
  • the network device 60 may be the first access network device, or the second access network device, or the first mobility management network element, or the second mobility management network element, or the session management network element, or IMS network element, or user plane gateway, or service gateway.
  • the processor 601 can be a general central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more programs for controlling the program of the present application. Execution of the integrated circuit.
  • CPU central processing unit
  • ASIC application-specific integrated circuit
  • Communication bus 602 can include a path for communicating information between the components described above.
  • the communication interface 604 uses a device such as any transceiver for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), and wireless local area networks (WLAN). )Wait.
  • a device such as any transceiver for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), and wireless local area networks (WLAN). )Wait.
  • RAN radio access network
  • WLAN wireless local area networks
  • the memory 603 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or a device that can store information and instructions.
  • ROM read-only memory
  • RAM random access memory
  • Other types of dynamic storage devices may also be electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical discs.
  • EEPROM electrically erasable programmable read-only memory
  • CD-ROM compact disc read-only memory
  • Storage optical storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic storage media or other magnetic storage devices, or capable of carrying or storing desired program code in the form of instructions or data structures And any other medium that can be accessed by a computer, but is not limited thereto.
  • the memory can exist independently and be connected to the processor via a bus.
  • the memory can also be integrated with the processor.
  • the memory 603 is used to store application code for executing the solution of the present application, and is controlled by the processor 601 for execution.
  • the processor 601 is configured to execute application code stored in the memory 603 to implement the method described below.
  • the processor 601 may include one or more CPUs, such as CPU0 and CPU1 in FIG.
  • network device 60 may include multiple processors, such as processor 601 and processor 608 in FIG. Each of these processors can be a single-CPU processor or a multi-core processor.
  • a processor herein may refer to one or more devices, circuits, and/or processing cores for processing data, such as computer program instructions.
  • network device 60 may also include an output device 605 and an input device 606.
  • Output device 605 is in communication with processor 601 and can display information in a variety of ways.
  • FIG. 6A is a schematic diagram showing the hardware structure of a terminal device 60A according to an embodiment of the present application.
  • the terminal device 60A includes at least one processor 601A, a communication bus 602A, a memory 603A, and at least one communication interface 604A.
  • processor 601A may include one or more CPUs, such as CPU0 and CPU1 in Figure 6A.
  • the terminal device 60A may include multiple processors, such as the processor 601A and the processor 608A in FIG. 6A.
  • the terminal device 60A may further include an output device 605A and an input device 606A.
  • the function of the various devices shown in Figure 6A, as well as other descriptions, can be exemplarily described above.
  • the first network and the second network may refer to two networks with different access systems and different core networks, for example, a 5G network with an NG RAN access system and an E-UTRAN access system.
  • the EPS network may also refer to two networks with different access systems but the same core network, for example, a 5G network with an NG RAN access system and a 5G network with an E-UTRAN access system.
  • the method provided by the embodiment of the present application is exemplified by the two networks in which the first network and the second network are different in the access system and the core network, but this should not be considered as limiting the scope of the application.
  • the method provided by the embodiment of the present application is also applicable to two networks with the same core network but different access systems.
  • the solution provided by the embodiment of the present application may be based on a service architecture, and the communication between the network elements may be based on a serviced interface or a non-serviced traditional interface, which is not specifically limited in this embodiment.
  • the embodiment of the present application provides a network switching method. As shown in FIG. 7, the method may include:
  • the first access network device receives first session management information from a session management (SM) network element, where the first session management information is used to request to establish a user plane tunnel for the voice service of the terminal device.
  • SM session management
  • the first session management information is used to request to establish a user plane tunnel for the voice service of the terminal device in the first network.
  • the voice service of the terminal device may be an IMS voice service.
  • the terminal device may be a calling terminal device of a voice service, or may be a called terminal device of a voice service.
  • a user plane tunnel may be referred to as a QoS flow in a 5G network.
  • the first access network device sends a handover request to the first mobility management network element according to the first session management information and the first condition, where the handover request is used to switch the terminal device from the first network to the second network.
  • the first condition includes: the first network cannot perform voice service.
  • the first access network device may be an NG RAN
  • the session management network element may be an SMF+PGW-C function network element
  • the first mobility management network element may be an AMF
  • the first network may be a 5G network
  • the second network It may be an EPS network.
  • the first network and the second network may both be 5G networks, except that the access systems of the first network and the second network are different.
  • the first session management information is session management information related to the user plane tunnel of the IMS voice service of the terminal device, and the first session management information may include a QoS parameter of the user plane tunnel of the IMS voice service of the terminal device, for example, a 5G QoS indicator.
  • 5G QoS indicator hereinafter referred to as 5QI
  • ARP allocation/retention priority
  • GRR guaranteed bit rate
  • abbreviation maximum bit rate
  • Other parameters may be included in the first session management information, such as MBR).
  • the SMF+PGW-C function network element may send the first session management information to the AMF in the session management with PDU modification command, and the AMF carries the first session management information in the N2 session.
  • the request (N2session request) is sent to the NG RAN.
  • the method provided by the embodiment of the present invention when the terminal device in the 5G network performs the voice service, can switch the terminal device to the EPS network, so that the terminal device can perform the IMS voice service on the EPS network, and solve the terminal in the 5G network.
  • the device cannot perform the problem of IMS voice service.
  • the voice-based terminal device should not initially select the NR access.
  • 5G core network 5Gcore network, referred to as 5GC
  • EPC evolved packet core
  • the NG RAN may send a handover request to the AMF, so that the terminal device in the 5G network switches from the 5G network to the EPS network, and the terminal device can perform the EPS network.
  • the IMS voice service enables the terminal device to stay in the 5G network to enjoy the high-speed data service service.
  • the IMS voice service is switched to the EPS network.
  • the embodiment of the present application provides a method for the terminal device to perform network switching in two scenarios.
  • Scenario 1 The first network cannot perform voice services, and the second network can perform voice services.
  • the first condition may further include: the second network supports the voice service, the signal quality of the second network meets the voice service requirement, and the network device of the first network, and the terminal device supports the switching between the first network and the second network. At least one of them.
  • the terminal device can perform network switching by using any one of the following manners and mode 2.
  • the first method is to notify the session to manage the information about the establishment of the user plane tunnel of the voice service of the network element, so that the network device in the first network establishes a user plane tunnel for the voice service of the terminal device, and the terminal device switches from the first network to the first network.
  • the user plane tunnel established by the network device in the first network for the voice service of the terminal device will be switched to the user plane tunnel of the voice service in the second network.
  • the specific manner 1 may include:
  • the first access network device sends second session management information to the session management network element, where the second session management information includes information that the establishment of the user plane tunnel of the voice service is accepted.
  • the first access network device may send the second session management information to the first mobility management network element in the N2 session response, and the first mobility management network element performs the second session management.
  • the information is carried to the session management network element in a session management with PDU modification command ack.
  • the second session management information includes the information that the establishment of the user plane tunnel of the voice service is accepted, in reality, the first access network device does not give the voice.
  • the service allocates wireless resources.
  • the method may further include: the first access network device determines, according to the first session management information and the first condition, that the radio resource is not allocated for the user plane tunnel of the voice service.
  • the session management network element receives the second session management information sent by the first access network device, and determines user plane tunnel related information of the voice service according to the second session management information.
  • the user plane tunnel related information of the voice service of the terminal device may be a packet detection, an enforcement rule, a reporting rule, and a core network tunnel information related to the user plane tunnel of the voice service. (core network tunnel information) and the like.
  • the session management network element sends user plane tunnel related information of the voice service to the user plane gateway.
  • the user plane gateway may be a UPF+PGW-U function network element.
  • the SMF+PGW-C function network element can carry the user plane tunnel related information of the voice service in the N4 session modification request to the UPF+PGW-U function network element.
  • the user plane gateway receives the user plane tunnel related information of the voice service sent by the session management network element, and establishes a user plane tunnel for the voice service according to the user plane tunnel related information of the voice service.
  • Steps S11-S14 may be performed before step 702, or may be performed before the user plane tunnel of the voice service starts to be switched after the step 702, and the user plane gateway may be the user established by the voice service by switching the user plane tunnel of the voice service.
  • the tunnel is also switched to the user plane tunnel of the voice service in the second network, so that the terminal device can perform voice service in the second network.
  • Manner 2 The reason information that the user plane tunnel of the voice service of the network element is denied is notified by the session, so that the session management network element re-establishes the voice service of the terminal device after the terminal device completes the handover of the first network to the second network. User plane tunnel.
  • the second method may specifically include:
  • the first access network device sends the third session management information to the session management network element, where the third session management information includes the reason information that the establishment of the user plane tunnel of the voice service of the terminal device is rejected.
  • the NG RAN may carry the third session management information in the N2 session response to the AMF, and the AMF then carries the third session management information in the session management response carrying the PDU session modification command to the SMF+PGW-C function.
  • the network element sends.
  • the reason information of the rejection may be: the terminal device is performing the handover process.
  • the session management network element receives the third session management information sent by the first access network device.
  • the session management network element determines that the terminal device switches from the first network to the second network.
  • Step S23 may be implemented in any one of mode (1) and mode (2).
  • the mode (1) is to set a timer in the session management network element, and when the timer expires, determine the terminal device.
  • the second method is: when receiving a modify bearer request, the session management network element determines that the terminal device switches from the first network to the second network, and the tunnel modification request is used to modify the terminal device. Signaling plane tunnel information for voice services.
  • the session management network element establishes a user plane tunnel for the voice service in the second network according to the cause information.
  • the terminal device may switch from the first network to the second network.
  • the second network establishes a user plane tunnel for the voice service.
  • the network device in the first network does not establish a user plane tunnel for the voice service, but after the session management network element determines that the terminal device is switched from the first network to the second network, The voice service of the terminal device establishes a user plane tunnel, so that the terminal device can perform voice service in the second network.
  • the second method provides a method for the terminal device to switch the network in the scenario where the first network cannot perform the voice service but the second network can perform the voice service.
  • the first access network device can switch in time when receiving the first session management information.
  • the terminal device in the first network to the second network, so that the terminal device in the first network continues to perform the voice call setup process on the second network, and the first access network device rejects the voice with the terminal device performing the handover process as the cause information.
  • the user plane tunnel of the service is established to trigger the user plane tunnel of the user plane gateway to re-establish the voice service after the terminal device successfully switches to the second network (due to the scenario, the second network can perform a voice session, so that the user plane tunnel can The establishment is successful), so that the terminal device performs voice service on the second network.
  • Scenario 2 The first network and the second network cannot perform voice services.
  • the first condition may further include: the second network is unable to perform voice service.
  • the terminal device can perform network switching in any of the following manners:
  • Manner 3 The reason information that the user plane tunnel of the voice service of the network element is denied is notified by the notification session, so that the session management network element re-establishes the voice service of the terminal device after the terminal device completes the handover of the first network to the second network.
  • the user plane tunnel is unsuccessful, the terminal device falls back to the 2G/3G network for voice service.
  • the third method can include:
  • Steps S31-S34 correspond to steps S21-S24, respectively, that is, step S31 is the same as step S21, step S32 is the same as step S22, step S33 is the same as step S23, and step S34 is the same as step S24. See Figure 9 for details.
  • the process of establishing the user plane tunnel may be specifically implemented by any one of the following processes P1 to P4.
  • the process P1 may include:
  • the serving gateway sends a tunnel establishment request (creat bearer request) to the second mobility management network element, where the tunnel establishment request is used to request a user plane tunnel for establishing a voice service for the terminal device.
  • the serving gateway may be an SGW
  • the second mobility management network element may be an MME
  • the second mobility management network element receives the tunnel establishment request sent by the serving gateway, and sends a tunnel establishment response (creat bearer response) to the serving gateway according to the second condition.
  • the tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the terminal device is rejected.
  • the second condition includes that the second network cannot perform the voice service, and the second condition may further include the terminal device being the terminal device that is switched from the first network to the second network.
  • the second mobility management network element determines that the second condition is established, the second mobility management network element refuses to establish a user plane tunnel for the voice service, and the information is included in the tunnel establishment response and sent to the serving gateway.
  • the serving gateway may notify the IMS network element that the user plane tunnel establishment denied information of the voice service is notified by the session management network element and the policy control function network element, so that the IMS network element triggers the circuit domain exchange of the terminal device to fall back ( Circuit switched fallback, referred to as CSFB).
  • the IMS network element can be a P-CSCF.
  • the process P2 may include:
  • the serving gateway sends a tunnel establishment request to the second mobility management network element, where the tunnel establishment request is used to request a user plane tunnel for establishing a voice service for the terminal device.
  • the second mobility management network element sends a bearer setup request to the second access network device, where the wireless tunnel establishment request is used to request to establish a user plane tunnel for the voice service of the terminal device.
  • the second access network device receives the wireless tunnel establishment request sent by the second mobility management network element, and sends a bearer setup response to the second mobility management network element according to the second condition.
  • the wireless tunnel establishment response includes information that the user plane tunnel of the voice service is rejected.
  • the second condition includes that the second network cannot perform the voice service, and the second condition may further include the terminal device being the terminal device that is switched from the first network to the second network.
  • the second access network device determines that the second condition is met, the second access network device refuses to establish a user plane tunnel for the voice service, and includes the information in the wireless tunnel establishment response to the second mobility management network. Yuan sent.
  • the second mobility management network element receives the wireless tunnel establishment response sent by the second access network device and sends a tunnel establishment response to the serving gateway according to the second condition.
  • the tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the terminal device is rejected.
  • the serving gateway may notify the IMS network element that the user plane tunnel establishment denied information of the voice service is notified by the session management network element and the policy control function network element, so that the IMS network element triggers the CSFB service of the terminal device.
  • the policy control function network element may be a PCF+PCRF function network element.
  • the process P3 may include:
  • the serving gateway sends a tunnel establishment request to the second mobility management network element, where the tunnel establishment request is used to request a user plane tunnel for establishing a voice service for the terminal device.
  • the second mobility management network element receives the tunnel establishment request sent by the serving gateway and sends a wireless tunnel establishment request to the second access network device, where the wireless tunnel establishment request is used to request to establish a user plane tunnel for the voice service of the terminal device. .
  • the second access network device receives the wireless tunnel establishment request sent by the second mobility management network element, and sends a wireless tunnel establishment response to the second mobility management network element according to the second condition.
  • the wireless tunnel establishment response includes information that the user plane tunnel of the voice service is rejected.
  • the second condition includes that the second network cannot perform the voice service, and the second condition may further include the terminal device being the terminal device that is switched from the first network to the second network.
  • the second access network device determines that the second condition is met, the second access network device refuses to establish a user plane tunnel for the voice service, and includes the information in the wireless tunnel establishment response to the second mobility management network. Yuan sent.
  • the second mobility management network element receives the wireless tunnel establishment response sent by the second access network device and sends a tunnel establishment response to the serving gateway according to the wireless tunnel establishment response.
  • the wireless tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the terminal device is rejected, and the tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the terminal device is rejected.
  • the serving gateway may notify the IMS network element that the user plane tunnel establishment denied information of the voice service is notified by the session management network element and the policy control function network element, so that the IMS network element triggers the CSFB service of the terminal device.
  • the second network cannot perform a voice session. Therefore, the user plane tunnel of the voice service cannot be established successfully.
  • the terminal device can be caused to fall back to the 2G/3G network for the voice service, and the terminal device needs to perform the CSFB service.
  • the joint registration is a necessary precondition for the terminal device to initiate the CSFB call.
  • the device completes the joint registration process for the EPS and CS domains. Therefore, in order to ensure that the terminal device successfully initiates the CSFB call, the CSFB service of the terminal device is triggered after the terminal device completes the joint registration, which may be implemented by any one of the following four methods W1 to W4.
  • the second mobility management network element determines that the terminal device completes the joint registration, and then performs step (12). Specifically, when the second mobility management network element determines to receive the association from the terminal device,
  • the registration completion message may be a tracking area update complete message, and the second mobility management network element determines that the terminal device completes the joint registration.
  • the second mobility management network element in the process P2, in the step (24), after the second mobility management network element determines that the second condition is established and the terminal device completes the joint registration, the second mobility management network element sends a tunnel establishment response to the serving gateway. . Specifically, when the second mobility management network element determines that the joint registration completion message from the terminal device is received, the second mobility management network element determines that the terminal device completes the joint registration.
  • the second mobility management network element determines that the terminal device completes the joint registration before performing step (32). Specifically, when the second mobility management network element determines that the joint registration completion message from the terminal device is received, the second mobility management network element determines that the terminal device completes the joint registration.
  • the second mobility management network element determines that the terminal device has completed the joint registration.
  • the serving gateway sends a tunnel establishment response, so that the IMS network element triggers the CSFB service of the terminal device after the terminal device completes the joint registration, thereby ensuring that the terminal device successfully initiates the CSFB call.
  • step S34 the session management network element establishes a user plane tunnel for the voice service in the second network after the first preset time period according to the reason information and the second condition.
  • the mode m1 is: the session management network element sends a tunnel establishment request to the serving gateway of the second network after the first preset time period according to the reason information and the second condition, where the tunnel establishment request is used to request the user plane tunnel for establishing the voice service.
  • the starting time point of the first preset time period may be a time point at which the reason information is received.
  • the mode m2 is: the session management network element sends a tunnel establishment request to the serving gateway of the second network according to the cause information, the tunnel establishment request is used to request to establish a voice service user plane tunnel; the session management network element receives the tunnel establishment response sent by the service gateway, and the tunnel Establishing a user plane tunnel including the voice service in the response to establish the rejected information; the session management network element sends a first message to the policy function control network element after the first preset time period according to the second condition, where the first message is used to indicate the voice The user plane tunnel establishment of the service failed.
  • the first message may be a credit control request (CCR), and the information that the user plane tunnel establishment fails may be included in the CCR.
  • CCR credit control request
  • the starting time point of the first preset time period may be a time point at which the reason information is received.
  • the terminal device when the IMS network element is delayed by the first preset time period to trigger the CSFB service of the terminal device, the terminal device has completed the joint registration, and the session management network element may be delayed by the first preset time period.
  • the request or the first message causes the IMS network element to delay the CSFB service of the terminal device by delaying the first preset time period, thereby ensuring that the terminal device successfully initiates the CSFB call.
  • mode W3 may include:
  • the W3-1 the IMS network element receives a request message for the terminal device to establish a voice service in a packet switching (PS) domain.
  • PS packet switching
  • the request message may specifically be an invite message.
  • the IMS network element determines that the voice service cannot be established in the PS domain of the first network or the second network.
  • the IMS network element determines that the terminal device completes the joint registration.
  • the IMS network element triggers the CSFB service of the terminal device.
  • the CSFB service of the terminal device is triggered, thereby ensuring that the terminal device successfully initiates the CSFB call.
  • the method may further include: determining, by the IMS network element, that the terminal device is registered in the first network according to the request message for establishing a voice service in the packet switched domain, and determining that the first network is received by the first network.
  • the request message may further include: determining, by the IMS network element, that the terminal device is registered in the first network according to the request message for establishing a voice service in the packet switched domain, and determining that the first network is received by the first network. The request message.
  • the W3-2 may include: the IMS network element acquires the voice service establishment failure information from the PS domain of the first network. Specifically, when the IMS network element fails to establish the information of the user plane tunnel of the voice service, the IMS network element determines The information that the terminal device is registered in the first network determines that the user plane tunnel establishment failure of the voice service is from the PS domain of the first network; or the IMS network element obtains the voice service establishment failure information from the PS domain of the second network, specifically, When the IMS network element fails to establish the user plane tunnel of the voice service, the information indicating that the user plane tunnel establishment failure of the voice service is determined by the terminal device to register with the second network is from the PS domain of the second network.
  • the voice service establishment failure information can be reported by other network devices to the IMS network element.
  • the W3-3 may include: after the IMS network element determines that the second preset time period cannot be established after the voice service is established in the PS domain of the first network or the second network, the IMS network element determines that the terminal device completes the joint registration; Alternatively, the IMS network element determines, according to the registration location information of the terminal device obtained from the policy control network element or the home subscriber server (HSS), that the terminal device completes the joint registration.
  • HSS home subscriber server
  • the policy control network element or the home subscriber server may actively report the registration location information of the terminal device to the IMS network element, or may be queried by the IMS network element from the policy control network element or the home subscriber server.
  • the W3-4 may include: the IMS network element sends a second message to the calling terminal device, where the second message is used to trigger the calling terminal device to initiate the CSFB calling voice service.
  • the W3-4 may include: the IMS network element sends a third message to the called domain selection device, where the third message is used to indicate the PS domain in the first network or the second network.
  • the called voice service establishment fails, so that the called domain selection device triggers the CSFB called voice service of the called terminal device.
  • the second message and the third message may be a 500 response message or a 380 response message or a 503 response message.
  • the fourth access network device notifies the session management network element that the user plane tunnel of the voice service is rejected. If the rejected information includes insufficient radio resources (or resource allocation failure), the session management network element is in the terminal device. After the handover from the first network to the second network is completed, the user plane tunnel is not established for the voice service of the terminal device, and the user plane tunnel establishment unsuccessful information is transmitted to the IMS network through the first network, so that the IMS network triggers the CSFB service of the terminal device. .
  • the method of the fourth embodiment includes: the first access network device sends the fourth session management information to the session management network element, where the fourth session management information includes the information that the user plane tunnel of the voice service is rejected, and the user plane tunnel of the voice service is established.
  • the rejected information includes insufficient wireless resources.
  • the session management network element does not re-establish the user plane tunnel for the voice service of the terminal device, but improves the handover process to ensure that the terminal device successfully initiates.
  • the CSFB call can be implemented by any one of the foregoing W3 and the following manners W4 to W8, wherein W5 and W6 are for the case where the terminal device is the calling terminal device.
  • mode W4 includes:
  • the second mobility management network element receives the fourth message sent by the first mobility management network element, where the fourth message is used to confirm that the terminal device completes the relocation.
  • the fourth message may specifically be a relocatioon request complete acknowledge message, where the relocation is performed by the terminal device switching from the first network to the second network, and the mobility management network element corresponding to the terminal device is heavy. The positioning is relocated from the first mobility management network element to the second mobility management network element.
  • the second mobility management network element determines that the second condition is established and the terminal device completes the joint registration.
  • the second condition includes that the second network cannot perform the voice service, and the second condition may further include the terminal device being the terminal device that is switched from the first network to the second network.
  • the W4-3 the second mobility management network element sends a tunnel modification request to the serving gateway, where the tunnel modification request is used to request to modify the signaling plane tunnel information of the voice service of the terminal device.
  • the serving gateway After receiving the tunnel modification request, the serving gateway sends a tunnel modification request to the session management network element, and the session management network element further sends a tunnel modification request to the user plane gateway, so that the user plane gateway establishes a corresponding voice service according to the signaling plane tunnel information of the voice service.
  • the second message may be sent to the terminal device (the meaning of the second message is the same as mentioned above), and the second message is required to pass the voice service.
  • the tunnel is sent to the terminal device.
  • the second mobility management network element sends a tunnel modification request to the serving gateway after determining that the terminal device completes the joint registration, thereby ensuring that the terminal device successfully initiates the CSFB call.
  • mode W5 includes:
  • the MME determines that the terminal device has completed the joint registration.
  • the W5-2 and the IMS network element determine that the voice service cannot be established in the PS domain of the first network or the second network.
  • the W5-3 the IMS network element sends a second message to the terminal device.
  • the MME determines the second message that the IMS network element sends to the terminal device after the terminal device completes the joint registration. Therefore, the terminal device can ensure that the CSFB call is successfully initiated.
  • mode W6 includes:
  • the W6-1 the IMS network element determines that the voice service cannot be established in the PS domain of the first network or the second network.
  • the W6-2 and the IMS network element send a second message to the user plane gateway.
  • the user plane gateway caches the second message.
  • the MME determines that the terminal device has completed the joint registration.
  • the MME sends a tunnel modification request to the user plane gateway.
  • the user plane gateway After receiving the tunnel modification request, the user plane gateway sends a second message to the terminal device.
  • the user plane gateway first caches the second message sent by the IMS network element, and sends a second message to the terminal device after receiving the tunnel modification request, because the tunnel modification request is performed after the MME determines that the terminal device completes the joint registration.
  • the gateway sends it, so that the terminal device can successfully initiate a CSFB call.
  • mode W7 includes:
  • the IMS network element determines that the voice service cannot be established in the PS domain of the first network or the second network.
  • the IMS network element delays transmitting the second message to the terminal device by using the second preset time period; when the terminal device is the called terminal device, the IMS network element is delayed.
  • the second preset time period sends a third message to the called domain selection device.
  • the terminal device when the IMS network element is delayed for a second preset time period to trigger the CSFB service of the terminal device, the terminal device has completed the joint registration, thereby ensuring that the terminal device successfully initiates the CSFB call.
  • the first preset time period and the second preset time period may be preset according to actual network conditions, and the first preset time period and the second preset time period may be the same or different, for example, the first preset time.
  • the segment can be 500ms, and the second preset time period can be 100ms.
  • the 5G network does not deploy a special CS domain as the 2G/3G network, and therefore cannot provide a CS voice service similar to the traditional voice for the terminal device, and the method provided by the embodiment of the present application is provided by the method and the fourth method.
  • the terminal device can also perform the CS voice service if the IMS voice service cannot be performed.
  • the present application further provides the following four embodiments for exemplary description of the foregoing method, wherein the application scenarios of the embodiment (1) and the embodiment (2) are both that the 5G network cannot perform the IMS voice service but the EPS network.
  • the scenarios in which the IMS voice service can be performed, and the application scenarios in the embodiment (3) and the embodiment (4) are scenarios in which the 5G network cannot perform the IMS voice service and the EPS network cannot perform the IMS voice service.
  • the calling party and the called side can be further divided into a calling side and a called side.
  • the UE and each network element in the method of the calling side are referred to as the UE and the network element on the calling side, and the called party is described.
  • the UE and each network element in the method on the side refer to the UE and the network element on the called side.
  • This embodiment provides a method for a calling UE to perform network switching. Referring to FIG. 18, the method includes:
  • the UE sends an invite message to the P-CSCF, where the invite message is used to request to establish an IMS voice service.
  • the UE is a UE in a 5G network
  • the invite message is a message for requesting a UE that is a 5G network to establish a voice service in a PS domain.
  • the P-CSCF establishes an IMS voice session for the UE according to the received invitation message sent by the UE.
  • the P-CSCF also sends the invite message to the nodes in the subsequent calling IMS network (for example, IMS nodes such as S-CSCF and TAS), and the nodes in the subsequent IMS network start processing the received invitation message, and the called UE may The invitation message of the calling UE forwarded by the called IMS network is received.
  • IMS nodes such as S-CSCF and TAS
  • the P-CSCF sends an authentication authorization request (AAR) to the PCF+PCRF to trigger establishment of a user plane tunnel of the IMS voice service of the UE.
  • AAR authentication authorization request
  • the AAR may carry the user identifier of the UE, the IMS application layer charging identifier, and the media description information of the IMS voice service.
  • the media description information may include at least one of the following information: a classifier identifier, a bandwidth requirement description information, a media type description information, and QoS parameters.
  • the P-CSCF may directly send the AAR to the PCF+PCRF, or may send the AAR to the PCF+PCRF after receiving the 183 response message sent by the S-CSCF in the IMS network.
  • the PCF+PCRF sends a packet data unit-connective access network (PDU-CAN) session modification to the SMF+PGW-C according to the media description information carried in the AAR sent by the P-CSCF.
  • PDU-CAN packet data unit-connective access network
  • the session modification process establishes a user plane tunnel by triggering the network element in the 5G network to serve the IMS voice service of the UE.
  • the PDU-CAN session modification carries QoS rules.
  • the QoS rules include QoS parameter profiles and packet filters.
  • the QoS parameter set is usually composed of one or more of the following QoS key parameters: GBR, ARP, 5QI and MBR.
  • the user plane tunnel in the 5G network generally refers to the QoS flow for transmitting user plane data.
  • the 5QI of the user plane tunnel of the IMS voice service may be equal to 1 or other values.
  • the IMS voice is used.
  • the SMF+PGW-C After receiving the PDU-CAN session modification procedure request sent by the PCF+PCRF network element, the SMF+PGW-C sends a session management request carrying the PDU session modification command to the AMF, where the request includes the first SM information.
  • the user plane tunnel allocates corresponding radio resources.
  • the NG RAN determines, according to the first SM information and the first condition, that the radio resource is not allocated to the user plane tunnel of the IMS voice service of the UE.
  • step 1807 may or may not be performed, and the embodiment of the present application does not specifically limit this.
  • the first condition may include the following conditions: (1) The 5G network cannot perform the IMS voice service, and the condition indicates that the IMS voice service is not deployed on the 5G network, or the current 5G network signal coverage difference is insufficient to meet the requirements of the IMS voice service;
  • the EPS network supports the voice service.
  • the condition can be configured by the operator as the local policy on the NG RAN.
  • the signal quality of the EPS network satisfies the voice service requirement.
  • the NG RAN can instruct the UE to measure and report the signal quality of the surrounding EPS cell.
  • the network equipment (AMF, NG RAN, etc.) of the 5G network and the UE support the handover between the 5G network and the EPS network, wherein whether the UE and the AMF support the 5G network and the EPS
  • the inter-network handover may be notified to the NG RAN by the AMF through the N2 message when the UE changes from the idle state to the connected state.
  • the NG RAN sends an N2 session response to the AMF.
  • the N2 session response includes second SM information, and the second SM information includes information that the establishment of the user plane tunnel of the IMS voice service of the UE is accepted.
  • the AMF sends a session management response carrying a PDU session modification command to the SMF+PGW-C according to the received N2 session response, where the second SM information is transparently transmitted to the SMF+PGW-C.
  • the SMF+PGW-C sends an N4 session modification request to the UPF+PGW-U according to the session management response that is sent by the received AMF and carries the PDU session modification command.
  • the N4 is an N4 interface between the SMF+PGW-C and the UPF+PGW-U.
  • the embodiment does not limit the interface name, that is, the message name is not the N4 session modification request.
  • a user plane tunnel in a 5G network generally refers to a QoS flow for transmitting user plane data
  • a user plane tunnel in an EPS network generally refers to a bearer for transmitting user plane data.
  • the user plane tunnel has been successfully established.
  • the UE After the UE is switched from the 5G network to the EPS network, after the UE receives the relevant signaling of the IMS voice service forwarded by the EPS network, the UE continues the subsequent IMS voice call setup process on the EPS network, thereby completely establishing the IMS voice session.
  • UPF+PGW-U will also send an N4 session modification response to SMF+PGW-C
  • SMF+PGW-C will send a PDU-CAN session modification to PCF+PCRF
  • PCF+PCRF will send to P-CSCF.
  • a re-authentication request (RAR) the P-CSCF sends a re-authentication answer (RAA) to the PCF+PCRF, so that the P-CSCF can know the user plane tunnel establishment of the IMS voice service. success.
  • RAR re-authentication request
  • RAA re-authentication answer
  • the NG RAN sends a handover request to the AMF according to the received first SM information and the first condition to trigger the UE to switch from the 5G network to the EPS network.
  • the handover request may be sent to the AMF.
  • the UE For the handover procedure of the UE to switch from the 5G network to the EPS network, refer to the standard protocol, and details are not described herein again.
  • the UE After the UE is switched from the 5G network to the EPS network, after the UE receives the relevant signaling of the IMS voice service forwarded by the EPS network, the UE continues the subsequent IMS voice call setup process on the EPS network, thereby completely establishing the IMS voice session.
  • This embodiment also provides a method for the called UE to perform network switching. Referring to FIG. 19, the method includes:
  • the P-CSCF receives an invite message sent by the S-CSCF, and establishes an IMS voice session for the UE according to the invite message.
  • the invite message is a message for requesting a UE that is a 5G network to establish a voice service in the PS domain.
  • the P-CSCF sends an invite message to the UE.
  • the UE receives the invite message sent by the P-CSCF and returns a 183 response message to the P-CSCF.
  • the P-CSCF receives the 183 response message sent by the UE, and sends a 183 response message to the S-CSCF.
  • the S-CSCF may further send a 183 response message to the calling party S-CSCF, and the calling party S-CSCF further sends a 183 response message to the calling party P-CSCF, and if the calling party P-CSCF receives the calling party S-
  • the 183 response message sent by the CSCF may forward the 183 response message to the calling UE.
  • Steps 1905 - 1914 and steps 1803-1812 respectively correspond to the same, that is, step 1905 is the same as step 1803, step 1906 is the same as step 1804, and so on, step 1914 is the same as step 1812, and the similar descriptions below have the same meaning.
  • the 5G terminal can be switched to the EPS network in time, so that the terminal device in the 5G continues to perform the IMS voice call setup process on the EPS network.
  • This embodiment provides a method for a calling UE to perform network switching. Referring to FIG. 20, the method includes:
  • Steps 2001-2006 correspond to steps 1801-1806, respectively.
  • the NG RAN sends an N2 session response to the AMF according to the first SM information and the first condition.
  • the N2 session response includes the third SM information
  • the reason information is that the UE is performing the handover process. Further, the reason information may be that the UE is performing the handover of the 5G network to the EPS network, so that the SMF+PGW-C determines, according to the reason information, that the user plane tunnel of the IMS voice service of the UE is re-initiated after the handover process of the UE ends. set up.
  • the first condition may include the following conditions: (1) The 5G network cannot perform the IMS voice service, and the condition indicates that the IMS voice service is not deployed on the 5G network, or the current 5G network signal coverage difference is insufficient to meet the requirements of the IMS voice service;
  • the EPS network supports the voice service.
  • the condition can be configured by the operator as the local policy on the NG RAN.
  • the signal quality of the EPS network satisfies the voice service requirement.
  • the NG RAN can instruct the UE to measure and report the signal quality of the surrounding EPS cell.
  • the network equipment (AMF, NG RAN, etc.) of the 5G network and the UE support the handover between the 5G network and the EPS network, wherein whether the UE and the AMF support the 5G network and the EPS
  • the inter-network handover may be notified to the NG RAN by the AMF through the N2 message when the UE changes from the idle state to the connected state.
  • the AMF sends a session management request carrying the PDU session modification command to the SMF+PGW-C according to the received N2 session response, where the third SM information is transparently transmitted to the SMF+PGW-C.
  • the SMF+PGW-C determines the IMS that is re-UE in the EPS network after the UE switches from the 5G network to the EPS network according to the third SM information in the session management request that is sent by the received AMF and carries the PDU session modification command.
  • the voice service establishes a user plane tunnel.
  • the SMF+PGW-C can determine that the UE has successfully switched from the 5G network to the EPS network through the received tunnel modification request sent by the SGW.
  • the SMF+PGW-C can also trigger the timer to start from receiving the third SM information by setting a timer. When the timer expires, it is determined that the UE has successfully switched from the 5G network to the EPS network.
  • the NG RAN sends a handover request to the AMF according to the received first SM information and the first condition to trigger the UE to switch from the 5G network to the EPS network.
  • the handover request may be sent to the AMF.
  • the process is specific to the standard protocol and will not be described here.
  • This embodiment also provides a method for the called UE to perform network switching. Referring to FIG. 21, the method includes:
  • the steps 2101-2104 and the steps 1901-1904 respectively correspond to the same, and the steps 2105-2113 and the steps 2003-2111 respectively correspond to the same.
  • This embodiment provides a method for a calling UE to perform network switching. Referring to FIG. 22, the method includes:
  • Steps 2201-2210 and steps 2001-2010 respectively correspond to the same.
  • the SGW forwards a tunnel establishment request to the MME.
  • the MME receives the tunnel establishment request and performs any one of process one (including a1), process two (including b1-b4), and process three (including c1-c4) in the following procedure.
  • A1 The MME sends a tunnel establishment response to the SGW according to the second condition, where the tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the UE is rejected.
  • the second condition may include that the second network cannot perform voice service, and may further include that the UE completes at least one of the joint registration for the UE and the UE that is handed over from the 5G network to the EPS network, where the second network cannot perform voice service. Specifically, the IMS voice service cannot be performed. If the UE completes the joint registration, the UE completes the joint registration process of the EPS and the CS domain.
  • the MME may determine, according to the received registration complete message sent by the UE, that the UE completes the joint registration.
  • the MME may send a wireless tunnel establishment request to the eNB for the IMS voice service and receive the response message, or may not send the wireless tunnel establishment request and the response response message, which is not limited herein.
  • the MME sends a radio tunnel establishment request to the eNB, and the radio tunnel establishment request is used to request a user plane tunnel for the IMS voice service of the UE.
  • the eNB receives the wireless tunnel establishment request, and sends a wireless tunnel establishment response to the MME according to the second condition, where the wireless tunnel establishment response includes information that the user plane tunnel establishment of the IMS voice service of the UE is rejected.
  • the second condition includes that the second network cannot perform the IMS voice service, and the UE may also be the UE that switches from the 5G network to the EPS network.
  • the MME receives the wireless tunnel setup response sent by the eNB. If the second condition is met, the MME determines that the UE completes the joint registration.
  • the wireless tunnel establishment response includes information that the user plane tunnel establishment of the IMS voice service of the UE is rejected.
  • step b3 when the MME determines that the registration completion message sent by the UE is received, the MME determines that the UE completes the joint registration.
  • the MME sends a tunnel establishment response to the SGW, where the tunnel establishment response includes information that the user plane tunnel of the IMS voice service of the UE is rejected.
  • the MME determines that the UE completes the joint registration.
  • the MME determines that the registration completion message sent by the UE is received, the MME determines that the UE completes the joint registration.
  • the second condition includes that the second network cannot perform the IMS voice service, and the UE may also be the UE that switches from the 5G network to the EPS network.
  • the MME sends a wireless tunnel establishment request to the eNB, and the wireless tunnel establishment request is used to request to establish a user plane tunnel for the IMS voice service of the UE.
  • the eNB receives the wireless tunnel establishment request sent by the MME, and sends a wireless tunnel establishment response to the MME according to the second condition, where the wireless tunnel establishment response includes information that the user plane tunnel establishment of the IMS voice service of the UE is rejected.
  • the MME receives the wireless tunnel establishment response sent by the eNB, and sends a tunnel establishment response to the SGW according to the wireless tunnel establishment response, where the tunnel establishment response includes the information that the user plane tunnel establishment of the IMS voice service of the UE is rejected.
  • the SGW receives a tunnel establishment response sent by the MME, and sends a tunnel establishment response to the SMF+PGW-C.
  • SMF+PGW-C sends CCR to PCF+PCRF.
  • the CCR can also be replaced by a message of another name, which is not limited herein, such as an IP-CAN session modification request.
  • the PCF+PCRF sends a credit control answer (CCA) to the SMF+PGW-C.
  • CCA credit control answer
  • the PCF+PCRF sends an RAR to the P-CSCF according to the CCR, where the RAR may carry indication information (or indication information for indicating resource allocation failure) indicating that the radio resource is insufficient.
  • the P-CSCF sends the RAA to the PCF+PCRF.
  • the P-CSCF determines that the IMS voice service of the UE cannot be established in the PS domain, according to the obtained indication information of the insufficient radio resources (or the indication information of the resource allocation failure).
  • the P-CSCF sends a 500 response message to the UE.
  • the UE may re-call the domain selection and initiate the CSFB call, and the UE side and the network side cooperate to perform the CSFB process, and finally may establish a voice call in the CS domain.
  • the P-CSCF may send a cancel message to the node in the IMS network such as the S-CSCF to cancel the already requested IMS voice service related call.
  • the mobility management network element of the serving UE is transformed from the AMF to the MME, and therefore, the MME allocates a new globally unique temporary identifier to the UE ( Globally unique temporary identity (GUTI).
  • GUI Globally unique temporary identity
  • the UE sends a tracking area update (TAU) request to the MME.
  • TAU tracking area update
  • the MME accepts the allocated new GUTI through the TAU.
  • the UE is brought to the MME to reply to the MME with a TAU Complete message (ie, a joint registration complete message) after receiving the TAU accept message carrying the new GUTI.
  • the IMS network is reached, so that the 500 response message sent by the IMS network can reach the UE after the UE completes the joint registration process of the EPS and the CS domain, and finally ensures that the UE successfully initiates the CSFB call.
  • the MME is configured to send the tunnel establishment to the SGW after determining that the UE completes the joint registration process of the EPS and the CS domain.
  • it can also be implemented by any one of the following methods 1 to 5.
  • SMF+PGW-C delays the first preset time period according to the second condition to send a tunnel establishment request to the SGW.
  • the second condition includes that the EPS network cannot perform IMS voice service.
  • SMF+PGW-C delays transmitting the CCR to the PCF+PCRF for a first preset time period.
  • the P-CSCF After the P-CSCF obtains the indication information of the insufficient radio resources or the indication information of the resource allocation failure, the P-CSCF sends a 500 response message to the UE by delaying a second preset time period.
  • Mode 5 The P-CSCF determines that the UE sends a 500 response message to the UE after completing the joint registration.
  • the mode 5 may include: after the P-CSCF determines that the second preset time period cannot be established after the voice service is established in the PS domain of the 5G network or the EPS network, the P-CSCF determines that the terminal device completes the joint registration; or, P- The CSCF determines that the terminal device completes the joint registration based on the registered location information of the terminal device obtained from the HSS/home location register (HLR).
  • HLR home location register
  • the first preset time period and the second preset time period may be set according to actual network communication conditions.
  • the first preset time period and the second preset time period may each be 500 ms.
  • This embodiment also provides a method for the called UE to perform network switching.
  • the method includes:
  • Steps 2301-2304 and steps 1901-1904 respectively correspond to the same.
  • Steps 2305-2320 correspond to steps 2203-2218, respectively.
  • the P-CSCF After the P-CSCF sends the 500 response message to the TAS in the IMS network, the P-CSCF sends the response message to the TAS in the IMS network, where the P-CSCF sends the response message to the TAS in the IMS network.
  • the called domain selection function module T-ADS in the TAS The called domain selection function module T-ADS in the TAS.
  • the P-CSCF After the P-CSCF obtains the indication information of the insufficient radio resources (or the indication information of the resource allocation failure), the P-CSCF sends a cancellation message to the UE to cancel the IMS voice service related session that has been requested.
  • Steps 2321 and 2322 do not define a sequential relationship.
  • the TAS in the IMS network re-selects the called session to the CS domain, and initiates a call to the CS domain call control device (such as a mobile switching center (MSC)) via a device such as an S-CSCF.
  • the CS domain call control device initiates a call to the MME via the SGs interface, and the MME triggers the CSFB process of the UE.
  • the UE may eventually establish a voice session in the CS domain through the CSFB process of the UE. See the related description in 3GPP TS 23.272 for details of the process. I will not repeat them here.
  • the IMS network is reached, so that the 500 response message sent by the IMS network can reach the TAS after the UE completes the joint registration process of the EPS and the CS domain, and finally ensures that the IMS called can be Converted to CSFB called to reach the UE.
  • the MME is configured to send the tunnel establishment to the SGW after determining that the UE completes the joint registration process of the EPS and the CS domain.
  • it can also be implemented by any one of the following methods 1 to 5.
  • SMF+PGW-C delays the first preset time period according to the second condition to send a tunnel establishment request to the SGW.
  • the second condition includes that the EPS network cannot perform IMS voice service.
  • SMF+PGW-C delays transmitting the CCR to the PCF+PCRF for a first preset time period.
  • Mode 3 After obtaining the indication information of the insufficient radio resources (or the indication information of the resource allocation failure), the P-CSCF delays sending a 500 response message to the TAS by using a second preset time period.
  • Mode 5 The P-CSCF determines that the UE sends a 500 response message to the TAS after completing the joint registration.
  • the mode 5 may include: after the P-CSCF determines that the second preset time period cannot be established after the voice service is established in the PS domain of the 5G network or the EPS network, the P-CSCF determines that the terminal device completes the joint registration; or, P- The CSCF determines that the terminal device completes the joint registration based on the registered location information of the terminal device obtained from the HSS/HLR.
  • the first preset time period and the second preset time period may be set according to actual network communication conditions.
  • the first preset time period and the second preset time period may each be 500 ms.
  • This embodiment provides a method for a calling UE to perform network switching. Referring to FIG. 24, FIG. 25, FIG. 26 and FIG. 27, the method includes:
  • Steps 2401-2406 correspond to steps 1801-1806, respectively.
  • the scenario in which the embodiment is applied is that the 5G network cannot perform the IMS voice service and the EPS network cannot perform the IMS voice service. Therefore, in order to ensure that the UE successfully initiates the CSFB call, the 500 response message sent by the IMS network needs to complete the EPS in the UE. The UE is only reached after the joint registration process of the CS domain.
  • any of the following Process 1 (see FIG. 24), Process 2 (see FIG. 25), Process 3 (see FIG. 26), and Process 4 (see FIG. 27) may be passed.
  • a process completes the network switching of the UE.
  • the NG RAN sends a handover request to the AMF according to the received first SM information and the first condition to trigger the UE to switch from the 5G network to the EPS network.
  • the first condition may include the following conditions: (1) The 5G network cannot perform the IMS voice service, and the condition indicates that the IMS voice service is not deployed on the 5G network, or the current 5G network signal coverage difference is insufficient to meet the requirements of the IMS voice service. (2) Network equipment (AMF, NG RAN, etc.) of the 5G network and the UE support handover between the 5G network and the EPS network, wherein whether the UE and the AMF support handover between the 5G network and the EPS network may be performed by the AMF at the UE The NG RAN is notified by the N2 message when the idle state changes to the connected state. (3) The EPS network does not support the voice service.
  • AMF Access Management Function
  • the condition can be configured by the operator as the local policy on the NG RAN.
  • the signal quality of the EPS network does not meet the voice service requirement.
  • the NG RAN can instruct the UE to measure and report the surrounding.
  • the signal quality of the EPS cell determines whether the signal quality of the EPS network satisfies the voice service requirement.
  • the handover preparation process ends, and the NG RAN sends a handover command to the UE.
  • the NG RAN sends an N2 session response to the AMF according to the first condition, where the N2 session response carries the fourth SM information, where the fourth SM information includes the information that the establishment of the user plane tunnel of the IMS voice service is rejected, and the user plane of the IMS voice service
  • the information that the establishment of the tunnel is rejected includes insufficient radio resources (or resource allocation failure).
  • the AMF sends a session management response carrying the PDU session modification command to the SMF+PGW-C according to the received N2 session response, where the fourth SM information is transparently transmitted to the SMF+PGW-C.
  • SMF+PGW-C parses the fourth SM information, it sends a PDU-CAN session modification message to the PCF+PCRF.
  • the PDU-CAN session modification message includes information indicating that the user plane tunnel establishment of the IMS voice service fails, and the indication information may be indication information of insufficient radio resources (or indication information of resource allocation failure).
  • the message name is defined as a PDU-CAN session modification message, which may be other message names, such as CCR.
  • the PCF+PCRF sends an RAR to the P-CSCF, where the RAR may carry information indicating that the user plane tunnel establishment of the IMS voice service fails.
  • the P-CSCF determines that the IMS voice service cannot be established in the PS domain according to the received information indicating that the user plane tunnel establishment fails.
  • the P-CSCF sends a 500 response message to the UE, and the message arrives at the UPF+PGW-U.
  • the 500 response message is transmitted to the UE through a tunnel (specifically, a QoS flow) of the 5G network.
  • the MME determines that the UE completes the joint registration.
  • the UE initiates the CSFB calling voice service, and the UE side and the network side cooperate to perform the CSFB process, and finally may establish a voice call in the CS domain.
  • the P-CSCF may send a cancel message to the node in the IMS network such as the S-CSCF to cancel the related call of the already requested IMS voice service.
  • the UPF+PGW-U sends a 500 response message to the UE after receiving the tunnel modification request, by causing the MME to go to the SMF+PGW-C and then to the UPF+PGW after determining that the UE completes the joint registration.
  • the NG RAN sends an N2 session response to the AMF according to the first condition, and the N2 session response carries the fourth SM information, where the fourth SM information includes the information that the establishment of the user plane tunnel of the IMS voice service is rejected, and the user plane tunnel of the IMS voice service
  • the establishment of rejected information includes insufficient radio resources (or resource allocation failure).
  • the NG RAN may determine the fourth SM information according to the first condition.
  • the first condition may include the following conditions: (1) The 5G network cannot perform the IMS voice service, and the condition indicates that the IMS voice service is not deployed on the 5G network, or the current 5G network signal coverage difference is insufficient to meet the requirements of the IMS voice service.
  • the NG RAN Network equipment (AMF, NG RAN, etc.) of the 5G network and the UE support handover between the 5G network and the EPS network, wherein whether the UE and the AMF support handover between the 5G network and the EPS network may be performed by the AMF at the UE
  • the NG RAN is notified by the N2 message;
  • the EPS network does not support the voice service, and the condition can be configured by the operator as the local policy on the NG RAN;
  • the signal quality of the EPS network does not satisfy the voice.
  • the NG RAN can determine whether the signal quality of the EPS network satisfies the voice service requirement by instructing the UE to measure and report the signal quality of the surrounding EPS cells.
  • the AMF sends a session management response carrying the PDU session modification command to the SMF+PGW-C according to the received N2 session response, where the fourth SM information is transparently transmitted to the SMF+PGW-C.
  • the SMF+PGW-C determines to keep the notification to the PCF+PCRF, that is, to suspend the information that the establishment of the user plane tunnel for notifying the PCF+PCRF of the voice service is rejected.
  • the NG RAN sends a handover request to the AMF according to the first condition and the first SM information.
  • the MME determines that the UE completes the joint registration.
  • SMF+PGW-C sends an IP CAN session modification message to PCF+PCRF.
  • the IP CAN session modification message carries information indicating that the user plane tunnel establishment of the IMS voice service fails, and the indication information may be indication information of insufficient radio resources (or indication information of resource allocation failure).
  • the message name is not limited to an IP-CAN session modification message, and may be other message names, such as CCR.
  • the PCF+PCRF sends an RAR to the P-CSCF, where the RAR carries information indicating that the user plane tunnel establishment of the IMS voice service fails.
  • the P-CSCF determines that the IMS voice service cannot be established in the PS domain according to the received information indicating that the user plane tunnel establishment fails.
  • the P-CSCF sends a 500 response message to the UE.
  • the UE initiates the CSFB calling voice service, and the UE side and the network side cooperate to perform the CSFB process, and finally may establish a voice call in the CS domain.
  • the P-CSCF sends a 500 response message to the UE after determining that the user plane tunnel establishment of the IMS voice service fails.
  • the PCF+PCRF sends the message to the P-CSCF.
  • the C1, the NG RAN sends an N2 session response to the AMF according to the first condition, and the N2 session response carries the fourth SM information, where the fourth SM information includes the information that the establishment of the user plane tunnel of the IMS voice service is rejected, and the user plane tunnel of the IMS voice service.
  • the establishment of rejected information includes insufficient radio resources (or resource allocation failure).
  • the NG RAN may determine the fourth SM information according to the first condition.
  • the first condition may include the following conditions: (1) The 5G network cannot perform the IMS voice service, and the condition indicates that the IMS voice service is not deployed on the 5G network, or the current 5G network signal coverage difference is insufficient to meet the requirements of the IMS voice service.
  • the NG RAN Network equipment (AMF, NG RAN, etc.) of the 5G network and the UE support handover between the 5G network and the EPS network, wherein whether the UE and the AMF support handover between the 5G network and the EPS network may be performed by the AMF at the UE
  • the NG RAN is notified by the N2 message;
  • the EPS network does not support the voice service, and the condition can be configured by the operator as the local policy on the NG RAN;
  • the signal quality of the EPS network does not satisfy the voice.
  • the NG RAN can determine whether the signal quality of the EPS network satisfies the voice service requirement by instructing the UE to measure and report the signal quality of the surrounding EPS cells.
  • the AMF sends a session management response carrying the PDU session modification command to the SMF+PGW-C according to the received N2 session response, where the fourth SM information is transparently transmitted to the SMF+PGW-C.
  • the SMF+PGW-C sends an N4 session modification request to the UPF+PGW-U according to the session management response sent by the received AMF carrying the PDU session modification command.
  • UPF+PGW-U feeds back the N4 session modification response to the SMF+PGW-C according to the received N4 session modification request.
  • SMF+PGW-C sends a PDU CAN session modification message to PCF+PCRF.
  • the PDU CAN session modification message carries information indicating that the user plane tunnel establishment of the IMS voice service fails, and the indication information may be indication information of insufficient radio resources (or indication information of resource allocation failure).
  • the message name is not limited to an IP-CAN session modification message, and may be other message names, such as CCR.
  • the PCF+PCRF sends an RAR to the P-CSCF, where the RAR carries information indicating that the user plane tunnel establishment of the IMS voice service fails.
  • the C8 and the P-CSCF determine that the IMS voice service cannot be established in the PS domain according to the received information indicating that the user plane tunnel establishment fails.
  • the P-CSCF sends a 500 response message to the UE, and the message arrives at UPF+PGW-U.
  • the NG RAN sends a handover request to the AMF according to the first condition and the first SM information.
  • the MME determines that the UE completes the joint registration.
  • the SMF+PGW-C sends a tunnel modification request to the UPF+PGW-U.
  • the UPF+PGW-U sends a 500 response message to the UE, and the UE initiates the CSFB calling voice service.
  • the UE side and the network side cooperate to perform the CSFB process, and finally may establish a voice call in the CS domain.
  • the 500-response message sent by the P-CSCF is buffered in the UPF+PGW-U by the first command, and after the MME determines that the UE completes the joint registration, the P-CSCF sends the 500 response message to the P-CSCF through the second command.
  • the terminal device sends, so that the 500 response message sent by the IMS network arrives at the UE after the UE completes the joint registration process of the EPS and the CS domain, and provides a guarantee for the UE to successfully initiate the CSFB call.
  • the NG RAN sends an N2 session response to the AMF according to the first condition, and the N2 session response carries the fourth SM information, where the fourth SM information includes the information that the establishment of the user plane tunnel of the IMS voice service is rejected, and the user plane tunnel of the IMS voice service
  • the establishment of rejected information includes insufficient radio resources (or resource allocation failure).
  • the NG RAN may determine the fourth SM information according to the first condition.
  • the first condition may include the following conditions: (1) The 5G network cannot perform the IMS voice service, and the condition indicates that the IMS voice service is not deployed on the 5G network, or the current 5G network signal coverage difference is insufficient to meet the requirements of the IMS voice service. (2) Network equipment (AMF, NG RAN, etc.) of the 5G network and the UE support handover between the 5G network and the EPS network, wherein whether the UE and the AMF support handover between the 5G network and the EPS network may be performed by the AMF at the UE The NG RAN is notified by the N2 message when the idle state changes to the connected state. (3) The EPS network does not support the voice service.
  • AMF Access Management Function
  • the condition can be configured by the operator as the local policy on the NG RAN.
  • the signal quality of the EPS network does not meet the voice service requirement.
  • the NG RAN can instruct the UE to measure and report the surrounding.
  • the signal quality of the EPS cell determines whether the signal quality of the EPS network satisfies the voice service requirement.
  • the AMF sends a session management response carrying the PDU session modification command to the SMF+PGW-C according to the received N2 session response, where the fourth SM information is transparently transmitted to the SMF+PGW-C.
  • SMF+PGW-C sends a PDU CAN session modification message to PCF+PCRF.
  • the message name is not limited to an IP-CAN session modification message, and may be other message names, such as CCR.
  • the PDU CAN session modification message carries information indicating that the user plane tunnel establishment of the IMS voice service fails, and the indication information may be indication information of insufficient radio resources (or indication information of resource allocation failure).
  • the PCF+PCRF sends an RAR to the P-CSCF, where the RAR carries information indicating that the user plane tunnel establishment of the IMS voice service fails.
  • the P-CSCF determines that the IMS voice service cannot be established in the PS domain according to the received information indicating that the user plane tunnel establishment fails.
  • the P-CSCF feeds back the RAA message to the PCF+PCRF.
  • the P-CSCF determines to send a 500 response message by delaying the second preset time period.
  • the NG RAN sends a handover request to the AMF according to the received first SM information and the first condition to trigger the UE to switch from the 5G network to the EPS network.
  • the UE After the step D8, the UE performs a handover procedure. After the handover process ends, the P-CSCF sends a 500 response message to the UE, and the UE initiates a CSFB calling voice service. The UE side and the network side cooperate to execute the CSFB process, and may eventually establish in the CS domain. Voice call.
  • the P-CSCF delays transmitting the 500 response message by using the second preset time period, so that the 500 response message sent by the IMS network arrives at the UE after the UE completes the joint registration process of the EPS and the CS domain, and successfully initiates the CSFB for the UE.
  • the call provides a guarantee.
  • the embodiment also provides a method for the called UE to perform network handover.
  • the scenario applied by the embodiment is that the 5G network cannot perform the IMS voice service and the EPS network cannot perform the IMS voice service. Therefore, in order to ensure the success of the UE.
  • the CSFB call is initiated.
  • the 500 response message sent by the IMS network needs to reach the TAS after the UE completes the joint registration process of the EPS and CS domains, so that the TAS selects the UE re-called domain to the CS domain to ensure the CSFB call is successful.
  • the method includes:
  • Steps 2801-2808 correspond to steps 1901-1908, respectively.
  • Steps 2809-2814 correspond to steps D1-D6, respectively.
  • the P-CSCF delays sending the 500 response message to the TAS by using the second preset time period.
  • the 500 response message is specifically sent to the called domain selection function module T-ADS in the TAS.
  • the P-CSCF delays transmitting the 500 response message for the second preset time period, so that the 500 response message sent by the P-CSCF arrives at the TAS after the UE completes the joint registration process of the EPS and the CS domain, which provides a guarantee for the CSFB call success.
  • the network switching method provided by the embodiment (3) and the embodiment (4) enables the 5G terminal device to switch to the EPS network in the IMS voice session establishment phase, and then uses the CSFB technology to drop the UE to the 2G/3G network in the EPS network. Finally, a voice call is initiated in the CS domain of the 2G/3G network.
  • the present application utilizes an EPS network as a springboard, and reuses the traditional 2G/3G network architecture to provide a method for performing voice services in a scenario where the 5G network and the EPS network cannot perform IMS voice services for the terminal equipment in the 5G network.
  • the 500 response message in the foregoing embodiment (1) to the embodiment (4) may also be a 380 response message or a 503 response message, and the RAR message may also be an abort-session-request (ASR) message.
  • the RAA message may be an abort-session-answer (ASA) message.
  • the embodiment of the present application further provides a network registration method, as shown in FIG. 28A, the method includes:
  • the first mobility management network element receives a registration request from the terminal device, where the registration request is used to request to register the terminal device with the first network.
  • the first mobility management network element may be an AMF, and the first network may be a 5G network.
  • the first mobility management network element sends the first indication information to the terminal device, where the first indication information is used to indicate that the voice service in the PS domain is supported.
  • the third condition may include: the first network supports moving the terminal device to the second network.
  • the first network supporting moving the terminal device to the second network may mean that the first network supports moving the terminal device to the second network by switching or redirecting or other means.
  • the first network supports moving the terminal device to the second network
  • the method includes: the first access network device in the first network supports the terminal when receiving the first session management information from the session management network element.
  • the device accesses the second network, and the first session management information is used to request to establish a user plane tunnel for the voice service of the terminal device.
  • the first access network device may be an NG RAN
  • the session management network element may be an SMF+PGW-C functional network element.
  • the first indication information may be carried in the registration accept message, and the voice service may be an IMS voice service, and the terminal device may be a terminal device that initiates a calling or called voice service.
  • the voice service may be an IMS voice service
  • the terminal device may be a terminal device that initiates a calling or called voice service.
  • the first mobility management network element may determine whether the third condition is established by any one of the following manners or other manners:
  • the first mobility management network element obtains whether the access network device and/or the core network element device in which the current terminal device is located has the capability to move the terminal device to the second The ability of the network to determine if the third condition is true.
  • the first mobility management network element determines whether the third condition is established by the configuration condition of the first mobility management device.
  • the configuration condition is configured whether the access network device and/or the core network element device where the terminal device is located can configure the terminal device. Move to the second network.
  • the core network of the first network and the second network are the same, and the access systems are different; or the core network and the access system of the first network and the second network are different.
  • the second network may be an EPS network.
  • the core network of the first network and the second network are the same, and the access systems are different,
  • the first network and the second network may both be 5G networks, with the difference that the access systems of the first network and the second network are different.
  • the first access network device may access the terminal device to the second network by sending a handover request to the first mobility management network element to switch the terminal device from the first network to the second network.
  • the terminal device may be the terminal device that initiates the calling PS domain voice service, or may initiate The terminal device of the called PS domain voice service.
  • the third condition may further include: supporting handover interoperation between the first network and the second network.
  • the first network supports moving the terminal device to the second network by handover.
  • the switching interoperation is supported between the first network and the second network, including: a switching interoperation interface exists between the first network and the second network.
  • a switching interoperation interface exists between the first network and the second network.
  • the handover interoperation interface may specifically be an N26 interface.
  • the second network may support the PS domain voice service, or may not support the PS domain voice service. If the second network is supported to support the PS domain voice service, the third condition may further include: the second network can support the PS domain voice service.
  • the method may further include: determining, by the first mobility management network element, that the terminal device is a terminal device that is mainly a voice service. Since the terminal device based on the data service is independent of the voice service, the optional method can distinguish the terminal type, and the terminal device that is mainly based on the data service does not need to implement the solution, that is, it is not required to determine whether the third condition is established. There is also no need to send the first indication information.
  • the method may further include: the terminal device generates a registration request, where the registration request carries the terminal device as the indication information of the terminal device that is mainly the voice service; the terminal device sends the registration request to the first mobility management network element;
  • the first mobility management network element determines that the terminal device is a terminal device that is mainly a voice service
  • the first mobility management network element determines, according to the registration request, that the terminal device is a terminal device that is mainly a voice service.
  • the terminal device carries the indication information of the terminal device that is the voice service-based terminal device by using the registration request, so that the signaling information of the first mobility management network element is not separately sent to the first mobility management network element, thereby saving signaling overhead.
  • the method may further include: determining, by the first mobility management network element, that the terminal device supports moving from the first network to the second network and continuing the voice service through the second network in the voice service initiation process. Initiate the process.
  • the above method can be implemented only when the terminal device supports the process of moving the voice service from the first network to the second network and continuing the voice service through the second network. Therefore, the information can be determined in advance to avoid The terminal device that affects the initiation process of the voice service from the first network to the second network and continues the voice service through the second network cannot be supported.
  • the registration request further includes indication information that the terminal device supports the process of initiating the voice service from the first network to the second network in the voice service initiation process, and the first mobility management network element determines The terminal device supports the process of initiating the voice service from the first network to the second network and the voice service in the voice service initiation process, including: the first mobility management network element determines, according to the registration request, that the terminal device supports the voice service initiation. The process of moving from the first network to the second network and continuing the initiation of the voice service through the second network.
  • the terminal device supports the indication information that the terminal device supports the process of initiating the voice service from the first network to the second network and continues the voice service through the second network by using the registration request, so that the terminal device does not need to separately send signaling.
  • the first mobility management network element indicates the information, which can save signaling overhead.
  • the method provided in this embodiment can be performed before any of the methods described before FIG.
  • the first mobility management network element may also send the first indication information to the terminal device under the third condition without using the third condition.
  • the method provided by the embodiment whether the first network supports the voice service of the terminal device, whether the first network has the capability of dropping the terminal device to the network capable of providing the voice service by using the handover or other manner when the terminal device initiates the voice service
  • the first mobility management network element indicates that the voice service of the PS domain of the terminal device is supported, thereby ensuring that the terminal device registers and resides in the first network without reselecting to other devices.
  • the network saves network resources and ensures that the terminal device performs the PS domain voice service registration process and initiates the PS domain voice call process through the first network.
  • the embodiment of the present application further provides a network registration method, as shown in FIG. 28B, which is used to specifically describe the method shown in FIG. 28A, and the method includes:
  • the UE sends a registration request to the AMF.
  • the registration request is used to request to register the UE in the first network, and the UE may send a registration request to the NG RAN, and the NG RAN forwards the registration request to the AMF.
  • the registration request may include indication information that the UE is the UE that is the voice service-based UE and the indication information that the UE supports the process of starting the voice service from the first network to the second network and continuing the voice service through the second network in the voice service initiation process.
  • the AMF receives a registration request from the UE.
  • the AMF determines, according to the registration request, that the UE supports the process of starting the voice service from the first network to the second network and continuing the voice service through the second network in the voice service initiation process.
  • the AMF determines, according to the registration request, that the UE is a UE that is mainly voice services.
  • step 2803B and step 2804B are in no particular order.
  • AMF determines whether the third condition is true.
  • the third condition includes: the first network supports moving the UE to the second network, and the second network is capable of supporting the voice service of the PS domain.
  • the AMF determines that the third condition is established as an example.
  • the AMF sends the first indication information to the UE, where the first indication information is used to indicate that the voice service of the PS domain is supported.
  • the first indication information may be carried in the registration accept message.
  • step 2806B the UE continues the subsequent process.
  • each of the above network devices includes a hardware structure and/or a software module corresponding to each function.
  • the present application can be implemented in a combination of hardware or hardware and computer software in combination with the elements and algorithm steps of the various examples described in the embodiments disclosed herein. Whether a function is implemented in hardware or computer software to drive hardware depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods to implement the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present application.
  • the embodiment of the present application may divide the function modules of each network device according to the foregoing method example.
  • each function module may be divided according to each function, or two or more functions may be integrated into one processing module.
  • the above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of the module in the embodiment of the present application is schematic, and is only a logical function division, and the actual implementation may have another division manner.
  • the embodiment of the present application further provides a network device 290.
  • the processing unit 2901 and the transceiver unit 2902 are included.
  • the network device may be a first access network device, a session management network element, a second mobility management network element, a second access network device, an IMS network element, or a first mobility management network element.
  • the processing unit 2901 is configured to receive, by using the transceiver unit 2902, first session management information from the session management network element, where the first session management information is used for requesting. Establishing a user plane tunnel for the voice service of the terminal device; sending, by the transceiver unit 2902, a handover request to the first mobility management network element according to the first session management information and the first condition, where the handover request is used to switch the terminal device from the first network to the first network
  • the second network, the first condition includes: the first network cannot perform voice service.
  • the first condition further includes: the second network supports the voice service, the signal quality of the second network meets the voice service requirement, and the network device of the first network, and the terminal device supports the switching between the first network and the second network. at least one.
  • processing unit 2901 is further configured to send the second session management information to the session management network element by using the transceiver unit 2902, where the second session management information includes information that the establishment of the user plane tunnel of the voice service is accepted.
  • the processing unit 2901 is further configured to determine, according to the first session management information and the first condition, that the radio resource is not allocated for the user plane tunnel of the voice service.
  • processing unit 2901 is further configured to send third session management information to the session management network element by using the transceiver unit 2902, where the third session management information includes information that the establishment of the user plane tunnel of the voice service is rejected.
  • the information about the establishment of the user plane tunnel of the voice service is rejected, including the reason information of the rejection.
  • the reason information is that the terminal device is performing the handover process.
  • the first condition further includes: the second network is unable to perform the voice service, and the processing unit 2901 is further configured to send the fourth session management information to the session management network element by using the transceiver unit 2902, where the fourth session management information includes the user of the voice service.
  • the establishment of the face tunnel is rejected, and the information about the establishment of the user plane tunnel of the voice service is rejected.
  • the network device 290 can switch the terminal device to the second network, so that the terminal device can perform the voice service on the second network, and the terminal device in the first network cannot be resolved.
  • the problem of voice service is not limited to voice service.
  • the processing unit 2901 is configured to receive, by the transceiver unit 2902, third session management information that is sent by the first access network device, where the third session management information includes the terminal device.
  • the reason information that the user plane tunnel of the voice service is rejected is determined; the terminal device is determined to be switched from the first network to the second network; and the user plane tunnel is established for the voice service in the second network according to the reason information.
  • the reason information is that the terminal device is performing a handover process.
  • the processing unit 2901 is configured to establish a user plane tunnel for the voice service in the second network after the first preset time period according to the reason information and the second condition, where the second condition includes The second network cannot perform the voice service.
  • the processing unit 2901 is configured to send, by using the transceiver unit 2902, a tunnel establishment request to the serving gateway of the second network after the first preset time period according to the reason information and the second condition.
  • the tunnel establishment request is used to request to establish a user plane tunnel of the voice service.
  • the processing unit 2901 is configured to send, by using the transceiver unit 2902, a tunnel establishment request to the serving gateway of the second network according to the cause information, where the tunnel establishment request is used to request to establish a voice service user plane tunnel;
  • the unit 2902 receives a tunnel establishment response sent by the serving gateway, where the tunnel establishment response includes information that the user plane tunnel establishment of the voice service is rejected; and the first pre-condition is received by the transceiver unit 2902 according to the second condition.
  • the first message is sent to the policy function control network element, where the first message is used to indicate that the user plane tunnel establishment of the voice service fails.
  • the network device 290 When the terminal device in the first network switches from the first network to the second network, the network device 290 establishes a user plane tunnel for the voice service in the second network according to the cause information. If the second network can perform the voice service, the user plane tunnel can The establishment is successful, so that the terminal device can perform voice service in the second network, and solves the problem that the terminal device in the first network cannot perform voice service.
  • the network device 290 can perform the following actions 1, action 2, action 3, or action 4.
  • the first processing unit 2901 is configured to receive, by using the transceiver unit 2902, a tunnel establishment request sent by the serving gateway, where the tunnel establishment request is used to request a user plane tunnel for establishing a voice service for the terminal device, and the transceiver unit 2902 is configured according to the second condition.
  • the serving gateway sends a tunnel establishment response, where the tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the terminal device is rejected, and the second condition includes that the second network cannot perform the voice service.
  • the second condition further includes: the terminal device is a terminal device that is switched from the first network to the second network.
  • processing unit 2901 is further configured to determine that the terminal device completes the joint registration.
  • the processing unit 2901 is specifically configured to determine that a joint registration complete message from the terminal device is received.
  • the network device 290 sends a tunnel establishment response to the serving gateway when the second network is unable to perform the voice service, so that the serving gateway transmits the rejected information of the user plane tunnel establishment to the IMS network, so that the IMS network triggers the CSFB service of the terminal device, and further The terminal device is caused to perform CS voice service.
  • the processing unit 2901 is configured to send, by using the transceiver unit 2902, a wireless tunnel establishment request to the second access network device, where the wireless tunnel establishment request is used to request to establish a user plane tunnel for the voice service of the terminal device; and receive, by the transceiver unit 2902 a wireless tunnel establishment response sent by the second access network device, where the wireless tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the terminal device is rejected; and the serving gateway is configured by the transceiver unit 2902 according to the second condition.
  • Sending a tunnel establishment response, the tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the terminal device is rejected, and the second condition includes that the second network cannot perform the voice service.
  • the second condition further includes: the terminal device is a terminal device that is switched from the first network to the second network.
  • the processing unit 2901 is specifically configured to determine that the second condition is established and the terminal device completes the joint registration, and sends a tunnel establishment response to the serving gateway by using the transceiver unit 2902.
  • the processing unit 2901 is specifically configured to determine that the registration completion message from the terminal device is received.
  • the network device 290 sends the rejected information of the user plane tunnel establishment to the serving gateway, so that the serving gateway transmits the rejected information of the user plane tunnel establishment to the IMS network, so that the IMS network triggers the CSFB service of the terminal device, thereby causing the terminal device to Conduct CS voice services.
  • the processing unit 2901 is configured to receive, by the transceiver unit 2902, a tunnel establishment request sent by the serving gateway, where the tunnel establishment request is used to request a user plane tunnel for establishing a voice service for the user equipment terminal device; if the second condition is established, determining the location The terminal device performs the joint registration, the second condition includes that the second network cannot perform the voice service; and the wireless tunnel establishment request is sent to the second access network device by the transceiver unit 2902, where the wireless tunnel establishment request is used for the request
  • the user equipment tunnel is established by the voice service of the terminal device, and the wireless tunnel establishment response sent by the second access network device is received by the transceiver unit 2902, where the wireless tunnel establishment response includes a user plane tunnel of the voice service of the terminal device. Establishing the rejected information; transmitting, by the transceiver unit 2902, a tunnel establishment response to the serving gateway according to the wireless tunnel establishment response, where the tunnel establishment response includes information that the user plane tunnel establishment of the voice service of the terminal device is rejected.
  • the second condition further includes: the terminal device is a terminal device that is switched from the first network to the second network.
  • the processing unit 2901 is specifically configured to determine that the registration completion message sent by the terminal device is received.
  • the network device 290 determines that the terminal device completes the joint registration and sends the information that the user plane tunnel establishment is rejected to the service gateway, so that the service gateway transmits the rejected information of the user plane tunnel establishment to the IMS network, so that the IMS network triggers the terminal device.
  • the CSFB service in turn, enables the terminal device to perform the CS voice service, and also ensures that the terminal device successfully initiates the CSFB call.
  • the processing unit 2901 is configured to receive, by the transceiver unit 2902, a fourth message sent by the first mobility management network element, where the fourth message is used to confirm that the terminal device completes relocation; and the transceiver unit 2902 is configured to serve according to the second condition.
  • the gateway sends a tunnel modification request, where the tunnel modification request is used to modify the signaling plane tunnel information of the voice service of the terminal device, where the second condition includes that the second network cannot perform the voice service.
  • the processing unit 2901 is specifically configured to determine that the second condition is established and the UE completes the joint registration; and the tunnel modification request is sent by the transceiver unit 2902 to the serving gateway.
  • the network device 290 When the second network cannot perform the voice service, the network device 290 sends a tunnel modification request to the service gateway, and the service gateway forwards the tunnel modification request to the session management network element, because the session management network element receives the tunnel modification request.
  • the terminal device sends a message for triggering the terminal device to initiate the CSFB call (ie, the second message in the above). Therefore, the network device 290 can trigger the terminal device to initiate the CSFB call when the second network cannot perform the voice service, thereby causing the terminal to make the terminal.
  • the device performs CS voice service.
  • the processing unit 2901 is configured to receive, by the transceiver unit 2902, a wireless tunnel establishment request sent by the second mobility management network element, where the wireless tunnel establishment request is used for the request.
  • the second access network device establishes a user plane tunnel for the voice service of the terminal device, and sends a wireless tunnel establishment response to the second mobility management network element according to the second condition by the transceiver unit 2902, where the wireless tunnel establishment response includes The user plane tunnel of the voice service establishes rejected information, and the second condition includes that the second network cannot perform the voice service.
  • the second condition further includes: the terminal device is a terminal device that is switched from the first network to the second network.
  • the network device 290 refuses to allocate the radio resource to the user plane tunnel when the second network is unable to perform the voice service, and the information about the user plane tunnel establishment of the voice service is carried in the wireless tunnel establishment response and sent to the second mobility management network element.
  • the second mobility management network element may transmit the rejected information of the user plane tunnel establishment to the IMS network, so that the IMS network triggers the CSFB service of the terminal device, and the terminal device performs the CS voice service.
  • the processing unit 2901 is configured to receive, by the transceiver unit 2902, a request message for establishing a voice service in the packet switched PS domain by the terminal device; determining that the first network or the second network cannot be used.
  • the PS domain establishes the voice service; determines that the terminal device completes the joint registration; triggers the circuit domain of the terminal device to switch back to the CSFB service.
  • processing unit 2901 is further configured to determine that the terminal device is registered in the first network.
  • the processing unit 2901 is specifically configured to acquire the voice service establishment failure information from the PS domain of the first network; or obtain the voice service establishment failure information from the PS domain of the second network.
  • the processing unit 2901 is specifically configured to determine that the terminal device cannot complete the joint registration after the second preset time period from the establishment of the voice service in the PS domain of the first network or the second network. Or determining that the terminal device completes the joint registration according to the registration location information of the terminal device obtained from the policy control network element or the home subscriber server.
  • the terminal device is a calling terminal device of the voice service
  • the processing unit 2901 is specifically configured to send, by using the transceiver unit 2902, a second message to the calling terminal device, where the second message is used to trigger the The calling terminal device initiates a CSFB calling service.
  • the terminal device is a called terminal device of the voice service
  • the processing unit 2901 is specifically configured to send, by using the transceiver unit 2902, a third message to the called domain selection device, where the third message is used to indicate The called voice service establishment of the PS domain of the first network or the second network fails, so that the called domain selection device triggers the CSFB called voice service of the called terminal device.
  • the network device 290 triggers the CSFB service of the terminal device when it is determined that the voice service cannot be established in the PS domain of the first network or the second network, and the terminal device completes the joint registration, which is necessary for the terminal device to initiate the CSFB call.
  • the condition is that the terminal device can successfully initiate the CSFB call, and the terminal device can perform the CS voice service.
  • the processing unit 2901 is configured to receive, by the transceiver unit 2902, a registration request from the terminal device, where the registration request is used to request to register the terminal device in the first network; 2901 is further configured to determine that the third condition is established, where the third condition includes: the first network supports moving the terminal device to the second network, and the second network is capable of supporting the voice service of the PS domain; the processing unit 2901 is further configured to send, by using the transceiver unit 2902 The terminal device sends the first indication information, where the first indication information is used to indicate that the voice service of the PS domain is supported.
  • the core network of the first network and the second network are the same, and the access systems are different; or the core network and the access system of the first network and the second network are different.
  • the first network supports moving the terminal device to the second network, where: the first access network device in the first network supports the terminal device when receiving the first session management information from the session management network element. Accessing the second network, the first session management information is used to request to establish a user plane tunnel for the voice service of the terminal device.
  • the third condition further includes: supporting handover interoperation between the first network and the second network.
  • the switching interoperation is supported between the first network and the second network, including: a switching interoperation interface exists between the first network and the second network.
  • the processing unit 2901 is further configured to determine that the terminal device is a terminal device that is mainly a voice service.
  • the registration request carries the indication information that the terminal device is a terminal device that is mainly a voice service
  • the processing unit 2901 is configured to determine, according to the registration request, that the terminal device is a terminal device that is mainly a voice service.
  • the processing unit 2901 is further configured to determine that the terminal device supports the process of starting the voice service from the first network to the second network in the voice service initiation process and continuing the voice service through the second network.
  • the registration request further carries the indication information that the terminal device supports the process of initiating the voice service from the first network to the second network and continues the voice service in the voice service initiation process
  • the processing unit 2901 is specifically configured to perform registration according to the The request determines that the terminal device supports the process of starting the voice service from the first network to the second network and continuing the voice service through the second network during the voice service initiation process.
  • the first network has the capability of the terminal device to fall back to the network capable of providing the voice service by switching or otherwise, when the terminal device initiates the voice service,
  • the first mobility management network element indicates that the voice service of the PS domain of the terminal device is supported, thereby ensuring that the terminal device registers and resides in the first network without reselecting to other networks, thereby saving network resources, and Ensure that the terminal device performs the PS domain voice service registration process and initiates the PS domain voice call process through the first network.
  • the embodiment of the present application further provides a terminal device 290A.
  • a processing unit 2901A and a transceiver unit 2902A are included.
  • the processing unit 2901A is configured to generate a registration request, where the registration request is used to request to register the terminal device with the first network, and the registration request carries the indication information of the terminal device that is the voice service-based terminal device; the processing unit 2901A is further configured to send and receive Unit 2902A sends a registration request to the first mobility management network element.
  • the registration request further includes indication information that the terminal device supports the process of starting the voice service from the first network to the second network in the voice service initiation process and continuing the voice service through the second network.
  • the core network of the first network and the second network are the same, and the access systems are different; or the core network and the access system of the first network and the second network are different.
  • the terminal device When the first network has the capability of the terminal device to fall back to the network capable of providing the voice service by switching or otherwise, when the terminal device initiates the voice service, the terminal device sends the first message according to the received first mobility management network element.
  • the indication information is registered and residing in the first network without reselecting to other networks, saving network resources, and ensuring that the terminal device normally performs the PS domain voice service registration process and initiates the PS domain voice call procedure through the first network.
  • the embodiment of the present application further provides a network device, including: a memory, a processor, and a communication interface; the memory is configured to store a computer to execute an instruction, the processor executes a computer-executed instruction stored in the memory, and causes the network device to implement the instruction corresponding through the communication interface.
  • a network device including: a memory, a processor, and a communication interface; the memory is configured to store a computer to execute an instruction, the processor executes a computer-executed instruction stored in the memory, and causes the network device to implement the instruction corresponding through the communication interface.
  • the network device may be a first access network device, a session management network element, a second mobility management network element, a second access network device, an IMS network element, or a first mobility management network element.
  • the processing unit 2901 may be the processor 601, and the transceiver unit 2902 may be the communication interface 604; as shown in FIG. 6 and FIG.
  • the processing unit 2901 may be the processor 601, and the transceiver unit 2902 may be the communication interface 604; when the schematic diagram of the second mobility management network element is shown in FIG. 6 and FIG.
  • the processing unit 2901 may be the processor 601, the transceiver unit 2902 may be the communication interface 604; when the schematic diagram of the second access network device shown in FIG. 6 and FIG. 29, the processing unit 2901 may be the processor 601, and the transceiver unit 2902 may be The communication interface 604; when shown in FIG. 6 and FIG. 29 is a schematic diagram of the IMS network element, the processing unit 2901 may be the processor 601, and the transceiver unit 2902 may be the communication interface 604; as shown in FIG. 6 and FIG. When a schematic diagram of the mobility management network element is used, the processing unit 2901 may be the processor 601, and the transceiver unit 2902 may be the communication interface 604.
  • the embodiment of the present application further provides a terminal device, including: a memory, a processor, and a communication interface; the memory is configured to store a computer to execute an instruction, the processor executes a computer-executed instruction stored in the memory, and causes the terminal device to implement an instruction corresponding through the communication interface.
  • a terminal device including: a memory, a processor, and a communication interface; the memory is configured to store a computer to execute an instruction, the processor executes a computer-executed instruction stored in the memory, and causes the terminal device to implement an instruction corresponding through the communication interface.
  • the embodiment of the present application also provides a computer readable storage medium, including instructions, when executed on a computer, causing a computer to execute the above method.
  • the embodiment of the present application also provides a computer program product comprising instructions that, when run on a computer, cause the computer to perform the above method.
  • the above embodiments it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • a software program it may be implemented in whole or in part in the form of a computer program product.
  • the computer program product includes one or more computer instructions.
  • the computer program instructions When the computer program instructions are loaded and executed on a computer, the processes or functions described in accordance with embodiments of the present application are generated in whole or in part.
  • the computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable device.
  • the computer instructions can be stored in a computer readable storage medium or transferred from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be from a website site, computer, server or data center Transmission to another website site, computer, server or data center via wired (eg coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (eg infrared, wireless, microwave, etc.).
  • the computer readable storage medium can be any available media that can be accessed by a computer or a data storage device that includes one or more servers, data centers, etc. that can be integrated with the media.
  • the usable medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (such as a solid state disk (SSD)) or the like.
  • a magnetic medium eg, a floppy disk, a hard disk, a magnetic tape
  • an optical medium eg, a DVD
  • a semiconductor medium such as a solid state disk (SSD)

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

本申请公开了一种网络切换方法及装置，用于解决终端设备无法进行IMS语音业务的问题。该方法包括：第一接入网设备接收来自会话管理网元的第一会话管理信息，第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道；第一接入网设备根据第一会话管理信息和第一条件向第一移动性管理网元发送切换请求，切换请求用于将终端设备从第一网络切换至第二网络，第一条件包括：第一网络无法进行语音业务。本申请适用于通信技术领域。

Description

网络切换方法及装置
本申请要求于2017年7月14日提交中国专利局、申请号为201710577345.7、申请名称为“网络切换方法及装置”的中国专利申请、以及于2017年8月14日提交中国专利局、申请号为201710693995.8、申请名称为“网络切换方法及装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及一种网络切换方法及装置。
背景技术
目前，一方面，很多运营商并没有或不打算在第五代(fifth-generation，简称5G)无线通信系统部署互联网协议多媒体子系统(internet protocol multimedia subsystem，简称IMS)语音业务，另一方面，5G网络中的频谱大多处于高频段，高频信号覆盖范围小，而IMS语音业务要求信号覆盖的范围比较大，从而导致在5G网络中的终端设备无法进行IMS语音业务。
发明内容
本申请实施例提供了一种网络切换方法及装置，用于解决终端设备无法进行IMS语音业务的问题。
为达到上述目的，本申请实施例提供如下技术方案：
第一方面，提供了一种网络切换方法，包括：第一接入网设备接收来自会话管理网元的第一会话管理信息，第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道；第一接入网设备根据第一会话管理信息和第一条件向第一移动性管理网元发送切换请求，切换请求用于将终端设备从第一网络切换至第二网络，第一条件包括：第一网络无法进行语音业务。
第一方面提供的方法，当第一网络中的终端设备进行语音业务时，可以通过将终端设备切换至第二网络，从而使得终端设备可以在第二网络进行语音业务，解决了第一网络中的终端设备无法进行语音业务的问题。
在一种可能的设计中，第一条件还包括：第二网络支持语音业务、第二网络的信号质量满足语音业务需求和第一网络的网络设备以及终端设备支持第一网络与第二网络间的切换中的至少一个。
在一种可能的设计中，该方法还包括：第一接入网设备向会话管理网元发送第二会话管理信息，第二会话管理信息包括语音业务的用户面隧道的建立被接受的信息。该种可能的设计，第一网络中的网元会为终端设备的语音业务建立用户面隧道。
在一种可能的设计中，在第一接入网设备向会话管理网元发送第二会话管理信息之前，该方法还包括：第一接入网设备根据第一会话管理信息和第一条件确定不为语音业务的用户面隧道分配无线资源。该种可能的设计，第一网络中的网元会为终端设备的语音业务建立用户面隧道。
在一种可能的设计中，该方法还包括：第一接入网设备向会话管理网元发送第三会话管理信息，第三会话管理信息包括语音业务的用户面隧道的建立被拒绝的信息。该种可能的设计，在终端设备完成从第一网络至第二网络的切换后，第二网络中的网元会为终端设备的语音业务建立用户面隧道。
在一种可能的设计中，语音业务的用户面隧道的建立被拒绝的信息包括拒绝的原因信息。该种可能的设计，在终端设备完成从第一网络至第二网络的切换后，第二网络中的网元会为终端设备的语音业务建立用户面隧道。
在一种可能的设计中，原因信息为：终端设备在执行切换流程。该种可能的设计，在终端设 备完成从第一网络至第二网络的切换后，第二网络中的网元会为终端设备的语音业务建立用户面隧道。
在一种可能的设计中，第一条件还包括：第二网络无法进行语音业务，该方法还包括：第一接入网设备向会话管理网元发送第四会话管理信息，第四会话管理信息包括语音业务的用户面隧道的建立被拒绝的信息，语音业务的用户面隧道的建立被拒绝的信息包括无线资源不足。该种可能的设计，在终端设备完成从第一网络至第二网络的切换后，第二网络中的网元不会为终端设备的语音业务建立用户面隧道。
第二方面，提供了一种网络切换方法，包括：会话管理网元接收第一接入网设备发送的第三会话管理信息，第三会话管理信息包括终端设备的语音业务的用户面隧道的建立被拒绝的原因信息；会话管理网元确定终端设备从第一网络切换至第二网络；会话管理网元根据原因信息在第二网络为语音业务建立用户面隧道。
第二方面提供的方法，当第一网络中的终端设备从第一网络切换至第二网络，会话管理网元根据原因信息在第二网络为语音业务建立用户面隧道，若第二网络可以进行语音业务，则用户面隧道可以建立成功，从而使得终端设备可以在第二网络中进行语音业务，解决了第一网络中的终端设备无法进行语音业务的问题。
在一种可能的设计中，原因信息为：终端设备在执行切换流程。
在一种可能的设计中，会话管理网元根据原因信息在第二网络为语音业务建立用户面隧道，包括：会话管理网元根据原因信息和第二条件在第一预设时间段后在第二网络为语音业务建立用户面隧道，第二条件包括第二网络无法进行语音业务。该种可能的设计，为终端设备完成联合注册预留出了第一预设时间段，通过对第一预设时间段的合理设置，可以使得终端设备在完成联合注册之后，再发起CSFB呼叫，从而保证终端设备成功发起CSFB呼叫。
在一种可能的设计中，会话管理网元根据原因信息和第二条件在第一预设时间段后在第二网络为语音业务建立用户面隧道，包括：会话管理网元根据原因信息和第二条件在第一预设时间段后向第二网络的服务网关发送隧道建立请求，隧道建立请求用于请求建立语音业务的用户面隧道。
在一种可能的设计中，会话管理网元根据被原因信息和第二条件在第一预设时间段后在第二网络为语音业务建立用户面隧道，包括：会话管理网元根据原因信息向第二网络的服务网关发送隧道建立请求，隧道建立请求用于请求建立语音业务用户面隧道；会话管理网元接收服务网关发送的隧道建立响应，隧道建立响应中包括语音业务的用户面隧道建立被拒绝的信息；会话管理网元根据第二条件在第一预设时间段后向策略功能控制网元发送第一消息，第一消息用于指示语音业务的用户面隧道建立失败。
第三方面，提供了一种网络切换方法，包括：第二移动性管理网元接收服务网关发送的隧道建立请求，隧道建立请求用于请求为终端设备建立语音业务的用户面隧道；第二移动性管理网元根据第二条件向服务网关发送隧道建立响应，隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息，第二条件包括第二网络无法进行语音业务。
第三方面提供的方法，第二移动性管理网元在第二网络无法进行语音业务时向服务网关发送隧道建立响应，以使得服务网关将用户面隧道建立被拒绝的信息传递至IMS网络，从而可以使得IMS网络触发终端设备的CSFB业务，进而使得终端设备进行CS语音业务。
在一种可能的设计中，第二条件还包括：终端设备为从第一网络切换至第二网络的终端设备。
在一种可能的设计中，第二移动性管理网元根据第二条件向服务网关发送隧道建立响应之前，该方法还包括：第二移动性管理网元确定终端设备完成了联合注册。该种可能的设计可以保证终端设备成功发起CSFB呼叫。
在一种可能的设计中，第二移动性管理网元确定终端设备完成了联合注册，包括：第二移动性管理网元确定接收到来自终端设备的联合注册完成消息。
第四方面，提供了一种网络切换方法，包括：第二移动性管理网元向第二接入网设备发送无 线隧道建立请求，无线隧道建立请求用于请求为终端设备的语音业务建立用户面隧道；第二移动性管理网元接收第二接入网设备发送的无线隧道建立响应，无线隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息；第二移动性管理网元根据第二条件向服务网关发送隧道建立响应，隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息，第二条件包括第二网络无法进行语音业务。
第四方面提供的方法，第二移动性管理网元将用户面隧道建立被拒绝的信息向服务网关发送，以使得服务网关将用户面隧道建立被拒绝的信息传递至IMS网络，从而可以使得IMS网络触发终端设备的CSFB业务，进而使得终端设备进行CS语音业务。
在一种可能的设计中，第二条件还包括：终端设备为从第一网络切换至第二网络的终端设备。
在一种可能的设计中，第二移动性管理网元根据第二条件向服务网关发送隧道建立响应，包括：第二移动性管理网元确定第二条件成立且终端设备完成联合注册；第二移动性管理网元向服务网关发送隧道建立响应。该种可能的设计可以保证终端设备成功发起CSFB呼叫。
在一种可能的设计中，第二移动性管理网元确定终端设备完成联合注册，包括：第二移动性管理网元确定接收到来自终端设备的注册完成消息。
第五方面，提供了一种网络切换方法，包括：第二移动性管理网元接收服务网关发送的隧道建立请求，隧道建立请求用于请求为用户设备终端设备建立语音业务的用户面隧道；若第二条件成立，第二移动性管理网元确定终端设备完成联合注册，第二条件包括第二网络无法进行语音业务；第二移动性管理网元向第二接入网设备发送无线隧道建立请求，无线隧道建立请求用于请求为终端设备的语音业务建立用户面隧道；第二移动性管理网元接收第二接入网设备发送的无线隧道建立响应，无线隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息；第二移动性管理网元根据无线隧道建立响应向服务网关发送隧道建立响应，隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息。
第五方面提供的方法，第二移动性管理网元确定终端设备完成联合注册后将用户面隧道建立被拒绝的信息向服务网关发送，以使得服务网关将用户面隧道建立被拒绝的信息传递至IMS网络，从而可以使得IMS网络触发终端设备的CSFB业务，进而使得终端设备进行CS语音业务，还可以保证终端设备成功发起CSFB呼叫。
在一种可能的设计中，第二条件还包括：终端设备为从第一网络切换至第二网络的终端设备。
在一种可能的设计中，第二移动性管理网元确定终端设备完成联合注册，包括：第二移动性管理网元确定接收到终端设备发送的注册完成消息。
第六方面，提供了一种网络切换方法，包括：第二接入网设备接收第二移动性管理网元发送的无线隧道建立请求，无线隧道建立请求用于请求第二接入网设备为终端设备建立语音业务的用户面隧道；第二接入网设备根据第二条件向第二移动性管理网元发送无线隧道建立响应，无线隧道建立响应包括语音业务的用户面隧道建立被拒绝的信息，第二条件包括第二网络无法进行语音业务。
第六方面提供的方法，第二接入网设备在第二网络无法进行语音业务时拒绝为用户面隧道分配无线资源，并将语音业务的用户面隧道建立被拒绝的信息携带在无线隧道建立响应中向第二移动性管理网元发送，第二移动性管理网元可以将用户面隧道建立被拒绝的信息传递给IMS网络，从而使得IMS网络触发终端设备的CSFB业务，进而使得终端设备进行CS语音业务。
在一种可能的设计中，第二条件还包括：终端设备为从第一网络切换至第二网络的终端设备。
第七方面，提供了一种网络切换方法，包括：IMS网元接收为终端设备在PS域建立语音业务的请求消息；IMS网元确定无法在第一网络或第二网络的PS域建立语音业务；IMS网元确定终端设备完成联合注册；IMS网元触发终端设备的CSFB业务。
第七方面提供的方法，IMS网元在确定无法在第一网络或第二网络的PS域建立语音业务、并且终端设备完成联合注册时，触发终端设备的CSFB业务，由于终端设备完成联合注册是终端设 备发起CSFB呼叫的必要条件，因此，第七方面提供的方法还可以保证终端设备成功发起CSFB呼叫，进而使得终端设备进行CS语音业务。
在一种可能的设计中，在IMS网元接收为终端设备在PS域建立语音业务的请求消息之后，该方法还包括：IMS网元确定终端设备注册于第一网络。
在一种可能的设计中，IMS网元确定无法在第一网络或第二网络的PS域建立语音业务，包括：IMS网元获取来自第一网络PS域的语音业务建立失败信息；或，IMS网元获取来自第二网络PS域的语音业务建立失败信息。
在一种可能的设计中，IMS网元确定终端设备完成联合注册，包括：IMS网元确定无法在第一网络或第二网络的PS域建立语音业务起的第二预设时间段后，IMS网元确定终端设备完成联合注册；或者，IMS网元根据从策略控制网元或归属用户服务器获得的终端设备的注册位置信息，确定终端设备完成联合注册。
在一种可能的设计中，终端设备为语音业务的主叫终端设备，IMS网元触发终端设备的CSFB业务，包括：IMS网元向主叫终端设备发送第二消息，第二消息用于触发主叫终端设备发起CSFB主叫业务。
在一种可能的设计中，终端设备为语音业务的被叫终端设备，IMS网元触发终端设备的CSFB业务，包括：IMS网元向被叫域选设备发送第三消息，第三消息用于指示在第一网络或第二网络的PS域的被叫语音业务建立失败，以使被叫域选设备触发被叫终端设备的CSFB被叫语音业务。
第八方面，提供了一种网络切换方法，包括：第二移动性管理网元接收第一移动性管理网元发送的第四消息，第四消息用于确认终端设备完成重定位；第二移动性管理网元根据第二条件向服务网关发送隧道修改请求，隧道修改请求用于修改终端设备的语音业务的信令面隧道信息，第二条件包括第二网络无法进行语音业务。
第八方面提供的方法，在第二网络无法进行语音业务时，第二移动性管理网元向服务网关发送隧道修改请求，服务网关会将隧道修改请求转发至会话管理网元，由于会话管理网元是在接收到隧道修改请求后，才会向终端设备发送用于触发终端设备发起CSFB呼叫的消息(即下文中的第二消息)，因此，第八方面提供的方法可以在第二网络无法进行语音业务时触发终端设备发起CSFB呼叫，进而使得终端设备进行CS语音业务。
在一种可能的设计中，第二移动性管理网元根据第二条件向服务网关发送隧道修改请求，包括：第二移动性管理网元确定第二条件成立且UE完成联合注册；第二移动性管理网元向服务网关发送隧道修改请求。该种可能的设计可以保证终端设备成功发起CSFB呼叫。
第九方面，提供了一种网络注册方法，该方法包括：第一移动性管理网元从终端设备接收注册请求，注册请求用于请求将终端设备注册于第一网络；若第三条件成立，第一移动性管理网元向终端设备发送第一指示信息，第一指示信息用于指示PS域的语音业务被支持，第三条件包括：第一网络支持将终端设备移动至第二网络。第九方面提供的方法，无论第一网络是否支持终端设备的语音业务，只要第一网络具备在终端设备发起语音业务时通过切换或其他方式将该终端设备回落至能提供语音业务的网络的能力，则在该终端设备向第一网络注册时，第一移动性管理网元便指示终端设备PS域的语音业务被支持，从而保证终端设备注册并驻留在第一网络而不重选至其他网络，节约网络资源，并且保证终端设备通过第一网络正常执行PS域语音业务注册流程和发起PS域语音呼叫流程。
在一种可能的设计中，第一网络和第二网络的核心网相同，接入制式不同；或者，第一网络和第二网络的核心网和接入制式均不同。
在一种可能的设计中，第一网络支持将终端设备移动至第二网络，包括：第一网络中的第一接入网设备支持在接收到来自会话管理网元的第一会话管理信息时，将终端设备接入第二网络，第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道。
在一种可能的设计中，第三条件还包括：第一网络与第二网络之间支持切换互操作，和，第 二网络能够支持PS域的语音业务中的至少一个。
在一种可能的设计中，第一网络与第二网络之间支持切换互操作，包括：第一网络和第二网络之间存在切换互操作接口。
在一种可能的设计中，在第一移动性管理网元向终端设备发送第一指示信息之前，所述方法还包括：第一移动性管理网元确定终端设备为以语音业务为主的终端设备。由于以数据业务为主的终端设备与语音业务无关，该可选的方法可以区分终端类型，对于以数据业务为主的终端设备并不需要执行这套方案，即不需要确定第三条件是否成立，也不需要发送第一指示信息。
在一种可能的设计中，注册请求中携带终端设备为以语音业务为主的终端设备的指示信息，第一移动性管理网元确定终端设备为以语音业务为主的终端设备，包括：第一移动性管理网元根据注册请求确定终端设备为以语音业务为主的终端设备。
在一种可能的设计中，在第一移动性管理网元向终端设备发送第一指示信息之前，该方法还包括:第一移动性管理网元确定终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程。由于只有终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的情况下，第一方面提供的方法才可以实施，因此，可以提前确定该信息，避免影响无法支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的终端设备。
在一种可能的设计中，注册请求中还携带终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的指示信息，第一移动性管理网元确定终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程，包括：第一移动性管理网元根据注册请求确定终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程。
第十方面，提供了一种网络注册方法，该方法包括：终端设备生成注册请求，注册请求用于请求将终端设备注册于第一网络，注册请求中携带终端设备为以语音业务为主的终端设备的指示信息；终端设备向第一移动性管理网元发送注册请求。
在一种可能的设计中，注册请求中还包括终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的指示信息。
在一种可能的设计中，第一网络和第二网络的核心网相同，接入制式不同；或者，第一网络和第二网络的核心网和接入制式均不同。
第十一方面，提供了一种网络设备，该网络设备可以为第一接入网设备、会话管理网元、第二移动性管理网元、第二接入网设备、IMS网元或第一移动性管理网元，当该网络设备为第一接入网设备时，该网络设备具有实现第一方面提供的任意一种方法的功能；当该网络设备为会话管理网元时，该网络设备具有实现第二方面提供的任意一种方法的功能；当该网络设备为第二移动性管理网元时，该网络设备具有实现第三方面、第四方面、第五方面或第八方面提供的任意一种方法的功能；当该网络设备为第二接入网设备时，该网络设备具有实现第六方面提供的任意一种方法的功能；当该网络设备为IMS网元时，该网络设备具有实现第七方面提供的任意一种方法的功能；当该网络设备为第一移动性管理网元时，该网络设备具有实现第九方面提供的任意一种方法的功能。网络设备实现的功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。该硬件或软件包括一个或多个与上述方法相对应的功能单元。
第十二方面，提供了一种终端设备，该终端设备具有实现第十方面提供的任意一种方法的功能，终端设备实现的功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。该硬件或软件包括一个或多个与第十方面提供的方法相对应的功能单元。
第十三方面、提供了一种网络设备，包括：存储器、处理器和通信接口；存储器用于存储计算机执行指令，处理器执行存储器存储的计算机执行指令，并通过通信接口使得网络设备实现上述方面提供的方法，具体的，该网络设备可以为第一接入网设备、会话管理网元、第二移动性管 理网元、第二接入网设备、IMS网元或第一移动性管理网元，当该网络设备为第一接入网设备时，该网络设备可以实现第一方面提供的任意一种方法；当该网络设备为会话管理网元时，该网络设备可以实现第二方面提供的任意一种方法；当该网络设备为第二移动性管理网元时，该网络设备可以实现第三方面、第四方面、第五方面或第八方面提供的任意一种方法；当该网络设备为第二接入网设备时，该网络设备可以实现第六方面提供的任意一种方法；当该网络设备为IMS网元时，该网络设备可以实现第七方面提供的任意一种方法；当该网络设备为第一移动性管理网元时，该网络设备具有实现第九方面提供的任意一种方法的功能。
第十四方面，提供了一种终端设备，包括：存储器、处理器和通信接口；存储器用于存储计算机执行指令，处理器执行存储器存储的计算机执行指令，并通过通信接口使得终端设备实现第十方面提供的任意一种方法。
第十五方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第一方面提供的任意一种方法。
第十六方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第二方面提供的任意一种方法。
第十七方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第三方面提供的任意一种方法。
第十八方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第四方面提供的任意一种方法。
第十九方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第五方面提供的任意一种方法。
第二十方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第六方面提供的任意一种方法。
第二十一方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第七方面提供的任意一种方法。
第二十二方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第八方面提供的任意一种方法。
第二十三方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第九方面提供的任意一种方法。
第二十四方面，提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行第十方面提供的任意一种方法。
第二十五方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第一方面提供的任意一种方法。
第二十六方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第二方面提供的任意一种方法。
第二十七方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第三方面提供的任意一种方法。
第二十八方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第四方面提供的任意一种方法。
第二十九方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第五方面提供的任意一种方法。
第三十方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第六方面提供的任意一种方法。
第三十一方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第七方面提供的任意一种方法。
第三十二方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第八方面提供的任意一种方法。
第三十三方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第九方面提供的任意一种方法。
第三十四方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第十方面提供的任意一种方法。
第十一方面至第三十四方面中任一种设计方式所带来的技术效果可参见第一方面至第十方面中不同设计方式所带来的技术效果，此处不再赘述。
附图说明
图1为本申请实施例提供的一种5G网络的架构示意图；
图1A为本申请实施例提供的一种终端设备接入5G CN的示意图；
图2为本申请实施例提供的一种EPS网络的架构示意图；
图3为本申请实施例提供的5G网络和EPS网络整合后的网络架构示意图；
图4为本申请实施例提供的EPS网络和IMS网络的通信示意图；
图5为本申请实施例提供的终端设备之间进行IMS语音通信的示意图；
图6为本申请实施例提供的一种网络设备的组成示意图；
图6A为本申请实施例提供的一种终端设备的组成示意图；
图7为本申请实施例提供的一种网络切换方法的交互流程图；
图8和图9分别为本申请实施例提供的一种网络切换的过程流程图；
图10-图12分别为本申请实施例提供的一种用户面隧道建立的过程示意图；
图13-图17分别为本申请实施例提供的一种保证终端设备成功发起CSFB呼叫的方法示意图；
图18-图28分别为本申请实施例提供的一种网络切换方法的交互流程图；
图28A为本申请实施例提供的一种网络注册方法的流程图；
图28B为本申请实施例提供的又一种网络注册方法的流程图；
图29为本申请实施例提供的一种网络设备的示意图；
图29A为本申请实施例提供的一种终端设备的示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述。其中，在本申请的描述中，除非另有说明，“/”表示或的意思，例如，A/B可以表示A或B；本文中的“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，在本申请的描述中，“多个”是指两个或多于两个。
本申请实施例提供的方法可以应用于无线通信系统，例如：全球移动通信(global system of mobile communication，简称GSM)系统，码分多址(code division multiple access，简称CDMA)系统，宽带码分多址(wideband code division multiple access wireless，简称WCDMA)系统，通用分组无线业务(general packet radio service，简称GPRS)系统，通用移动通信系统(universal mobile melecommunications system，简称UMTS)，EPS网络和5G网络，还可以用于未来的无线通信系统。
具体的，本申请实施例提供的方法可以应用于图1所示的5G网络，如图1所示，该5G网络可以包括：鉴权服务器功能(authentication server function，简称AUSF)网元、接入和移动管理功能(mobility management function，简称AMF)网元、数据网络(data network，简称DN)、统一数据管理(unified data management，简称UDM)网元、策略控制功能(policy control function，简称PCF)网元、(无线)接入网((radio)access network，简称(R)AN)设备、用户面功能 (user plane function，简称UPF)网元、终端设备、应用功能(application function，简称AF)网元、会话管理功能(session management function，简称SMF)网元。
其中，5G网络的(R)AN设备可以是下一代(next generation，简称NG)RAN设备，也可以是演进型通用陆地无线接入网(evolved universal terrestrial radio access network，简称E-UTRAN)设备，5G网络可同时连接至上述两种接入网设备，也即5G网络可能同时具备两种不同无线接入制式(radio access type，简称RAT)。参见图1A，终端设备可以通过E-UTRAN设备或NG RAN设备接入5G核心网(core network，简称CN)，本申请实施例以终端设备通过NG RAN注册于5G网络并在NG RAN接入制式下发起语音业务为例对本申请实施例提供的方法进行示例性说明。
控制面(control plane，简称CP)功能网元包括：UDM网元、AUSF网元、PCF网元、AMF网元和SMF网元。
具体的，(R)AN设备主要功能包括：提供无线连接；UPF网元主要功能包括：使数据包路由和转发、移动性锚点、上行分类器来支持路由业务流到DN、BP来支持多归属分组数据单元(packet data unit，简称PDU)会话等；DN可以为运营商服务，互联网接入或者第三方服务；AMF网元主要功能包含管理用户注册、可达性检测、SMF节点的选择、移动状态转换管理等；SMF网元主要功能包括：控制会话的建立、修改和删除，用户面节点的选择等；PCF网元主要功能包括：策略决策点，提供基于业务数据流和应用检测，门控，服务质量(quality of service，简称QoS)和基于流的计费控制等规则；AF网元主要功能包括：与第三代合作伙伴计划(3rd generation partnership project，简称3GPP)核心网交互来提供服务，来影响业务流路由、接入网能力开放、策略控制等；AUSF网元主要功能包括：提供鉴权服务；UDM网元主要功能包括：存储用户签约数据。
其中，终端设备也可以称为用户设备(user equipment，简称UE)、接入终端、用户单元、用户站、移动站、移动台、远方站、远程终端、移动设备、用户终端、终端、无线通信设备、用户代理或用户装置。终端设备还可以是无线局域网(wireless local area networks，简称WLAN)中的站点(station，简称ST)，可以是蜂窝电话、无绳电话、会话启动协议(session initiation protocol，简称SIP)电话、无线本地环路(wireless local loop，简称WLL)站、个人数字处理(personal digital assistant，简称PDA)设备、具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它处理设备、车载设备、可穿戴设备(也可以称为穿戴式智能设备)。终端设备还可以为下一代通信系统中的终端设备，例如，5G中的终端设备或者未来演进的公共陆地移动网络(public land mobile network，简称PLMN)中的终端设备，新无线(new radio，简称NR)通信系统中的终端设备等。
具体的，本申请实施例提供的方法还可以应用于图2所示的演进分组系统(evolved packet system，简称EPS)网络(即通常所说的4G网络)，如图2所示，该EPS网络可以包括下述多个功能网元：终端设备、E-UTRAN(具体可以为eNodeB)、业务网关(serving gateway，简称SGW)、分组数据网关(packet data network gateway，简称PGW)、移动性管理网元(mobility management entity，简称MME)、归属用户服务器(home subscriber server，简称HSS)、移动交换中心(mobile switching center，简称MSC)和策略和计费规则功能(policy and charging rules function，简称PCRF)网元。
在既部署5G网络又部署EPS网络的情况下，可以将5G网络中的功能网元和EPS网络中的功能网元进行整合，使得5G网络和EPS网络可以进行交互，参见图3，整合后的网络中的功能网元包括：HSS+UDM功能网元(是指既具备HSS的功能又具备UDM的功能的功能网元)、PCF+PCRF功能网元(是指既具备PCF的功能又具备PCRF的功能的功能网元)、SMF+PGW-C功能网元(是指既具备SMF的功能又具备分组数据网网关-控制面(packet data network gateway-control plane，简称PGW-C)的功能的功能网元)、UPF+PGW-U功能网元(是指既具备UPF的功能又具备分组数据网网关-用户面(packet data network gateway-user plane，简称PGW-U) 的功能的功能网元)、SGW、MME、E-UTRAN、AMF、NGRAN和终端设备。在本申请中的各实施例中，HSS+UDM功能网元、PCF+PCRF功能网元、SMF+PGW-C功能网元、UPF+PGW-U仅仅是举例说明，每个网元也可以是相互分离的两个网元，在此不做限定。
目前比较成熟的语音业务方案包括EPS网络中的IMS语音业务方案和2G/3G网络中的电路交换(circuit switching，简称CS)语音业务方案。由于现有技术中5G网络不支持IMS和CS语音业务，本申请实施例提供了一种网络切换方法，使得终端设备可以在需要进行语音业务时，从5G网络切换至EPS网络或2G/3G网络进行语音业务。
参见图2，若运营商的IP业务为IMS语音业务，则EPS网络和IMS网络的通信示意图可以参见图4，其中，IMS网络包括：代理-呼叫会话控制功能(Proxy-Call Session Control Funtion，简称P-CSCF)/会话边缘控制(Session Border Control，简称SBC)、查询呼叫会话控制功能(interrogating-call session control funtion，简称I-CSCF)/服务呼叫会话控制功能(serving-call session control funtion，简称S-CSCF)、电话应用服务器(telephony application server，简称TAS)和IMS媒体网关(IMS media gateway，简称IMS MGW)，其中，被叫域选功能模块(terminating access domain selection，简称T-ADS)可以被包含在TAS中，因此，下文中的被叫域选设备可以认为是TAS。TAS也可以为业务集中和连续性应用服务器(service centralization and continuity application server，简称SCC AS)。
终端设备在进行IMS语音业务时，主叫终端设备和被叫终端设备之间通信的过程可以参见图5，具体包括：主叫终端设备将与呼叫相关的信息向主叫接入网发送，与呼叫相关的信息经过主叫接入网、主叫核心网、主叫IMS网络、被叫IMS网络、被叫核心网和被叫接入网后到达被叫终端设备，被叫终端设备向主叫终端设备反馈的信息按照相反的方向发送即可。
如图6所示，为本申请实施例提供的一种网络设备60的硬件结构示意图，该包括至少一个处理器601，通信总线602，存储器603以及至少一个通信接口604。该网络设备60可以是本申请中的第一接入网设备、或第二接入网设备、或第一移动性管理网元、或第二移动性管理网元、或会话管理网元、或IMS网元、或用户面网关、或服务网关。
处理器601可以是一个通用中央处理器(central processing unit，简称CPU)，微处理器，特定应用集成电路(application-specific integrated circuit，简称ASIC)，或一个或多个用于控制本申请方案程序执行的集成电路。
通信总线602可包括一通路，在上述组件之间传送信息。
通信接口604，使用任何收发器一类的装置，用于与其他设备或通信网络通信，如以太网，无线接入网(radio access network，简称RAN)，无线局域网(wireless local area networks，简称WLAN)等。
存储器603可以是只读存储器(read-only memory，简称ROM)或可存储静态信息和指令的其他类型的静态存储设备，随机存取存储器(random access memory，简称RAM)或者可存储信息和指令的其他类型的动态存储设备，也可以是电可擦可编程只读存储器(electrically erasable programmable read-only memory，简称EEPROM)、只读光盘(compact disc read-only memory，简称CD-ROM)或其他光盘存储、光碟存储(包括压缩光碟、激光碟、光碟、数字通用光碟、蓝光光碟等)、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质，但不限于此。存储器可以是独立存在，通过总线与处理器相连接。存储器也可以和处理器集成在一起。
其中，存储器603用于存储执行本申请方案的应用程序代码，并由处理器601来控制执行。处理器601用于执行存储器603中存储的应用程序代码，从而实现下文中描述的方法。
在具体实现中，作为一种实施例，处理器601可以包括一个或多个CPU，例如图6中的CPU0和CPU1。
在具体实现中，作为一种实施例，网络设备60可以包括多个处理器，例如图6中的处理器 601和处理器608。这些处理器中的每一个可以是一个单核(single-CPU)处理器，也可以是一个多核(multi-CPU)处理器。这里的处理器可以指一个或多个设备、电路、和/或用于处理数据(例如计算机程序指令)的处理核。
在具体实现中，作为一种实施例，网络设备60还可以包括输出设备605和输入设备606。输出设备605和处理器601通信，可以以多种方式来显示信息。
如图6A所示，为本申请实施例提供的一种终端设备60A的硬件结构示意图，该终端设备60A包括至少一个处理器601A，通信总线602A，存储器603A以及至少一个通信接口604A。
在具体实现中，作为一种实施例，处理器601A可以包括一个或多个CPU，例如图6A中的CPU0和CPU1。
在具体实现中，作为一种实施例，该终端设备60A可以包括多个处理器，例如图6A中的处理器601A和处理器608A。
在具体实现中，作为一种实施例，该终端设备60A还可以包括输出设备605A和输入设备606A。图6A中所示的各个器件的作用以及其他说明可以示例性的参见上文。
在本申请实施例中，第一网络和第二网络可以是指接入制式不同且核心网也不同的两个网络，例如，具备NG RAN接入制式的5G网络和具备E-UTRAN接入制式的EPS网络；也可以是指接入制式不同但核心网相同的两个网络，例如，具备NG RAN接入制式的5G网络和具备E-UTRAN接入制式的5G网络。本申请实施例中以第一网络和第二网络为接入制式和核心网均不同的两个网络对本申请实施例提供的方法做示例性说明，但这不应当认为是对本申请保护范围的限定，本申请实施例提供的方法同样适用于核心网相同但接入制式不同的两个网络。
本申请实施例提供的方案可以基于服务化架构，各个网元之间的通信可以基于服务化接口或非服务化的传统接口，本申请实施例并不对此作具体限定。
本申请实施例提供了一种网络切换方法，如图7所示，该方法可以包括：
701、第一接入网设备接收来自会话管理(session management，简称SM)网元的第一会话管理信息，第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道。
具体的，第一会话管理信息用于请求在第一网络为终端设备的语音业务建立用户面隧道。终端设备的语音业务可以为IMS语音业务。
终端设备可以为语音业务的主叫终端设备，也可以为语音业务的被叫终端设备。用户面隧道在5G网络中可以称为QoS flow(QoS流)。
702、第一接入网设备根据第一会话管理信息和第一条件向第一移动性管理网元发送切换请求(handover required)，切换请求用于将终端设备从第一网络切换至第二网络，第一条件包括：第一网络无法进行语音业务。
其中，第一接入网设备可以为NG RAN，会话管理网元可以为SMF+PGW-C功能网元，第一移动性管理网元可以为AMF，第一网络可以为5G网络，第二网络可以为EPS网络，另外，第一网络和第二网络可以均为5G网络，区别在于第一网络和第二网络的接入制式不同。
第一会话管理信息为与终端设备的IMS语音业务的用户面隧道相关的会话管理信息，第一会话管理信息中可以包含终端设备的IMS语音业务的用户面隧道的QoS参数，例如，5G QoS指示(5G QoS indicator，下文中称为5QI)＝1、分配/保持优先级(allocation/retention priority，简称ARP)、保证比特速率(guaranteed bit rate，简称GBR)和最大比特率(maximum bit rate，简称MBR)等参数，第一会话管理信息中还可以包括其他信息。
SMF+PGW-C功能网元可以将第一会话管理信息携带在携带PDU修改命令的会话管理请求(session management with PDU modification command)中向AMF发送，AMF再将第一会话管理信息携带在N2会话请求(N2session request)中向NG RAN发送。
本申请实施例提供的方法，当5G网络中的终端设备进行语音业务时，可以通过将终端设备切换至EPS网络，从而使得终端设备可以在EPS网络进行IMS语音业务，解决了5G网络中的终 端设备无法进行IMS语音业务的问题。
根据目前5G网络协议中的规定，对于以语音为主(voice centric)的终端设备，若5G网络的网络侧不支持IMS语音业务，则以语音为主的终端设备初始就不应该选择NR接入5G核心网(5Gcore network，简称5GC)，或者即使接入5GC，也要重选接入E-UTRAN和演进型分组核心网(evolved packet core，简称EPC)，那么若5G网络不支持IMS语音业务，则终端设备将不能停留在5G网络，享受高速的数据业务服务。而本申请实施例提供的方法，在5G网络无法进行IMS语音业务时，NG RAN可以向AMF发送切换请求，使得5G网络中的终端设备从5G网络切换至EPS网络，终端设备在EPS网络可以进行IMS语音业务，进而使得终端设备可以先停留在5G网络中享受高速的数据业务服务，在需要进行IMS语音业务时，再切换至EPS网络进行IMS语音业务。
进一步的，为了保证5G网络中的终端设备可以顺利的进行语音业务，本申请实施例提供了在两种场景下，终端设备进行网络切换的方法。
场景一、第一网络无法进行语音业务，第二网络可以进行语音业务。
在该场景下，第一条件还可以包括：第二网络支持语音业务、第二网络的信号质量满足语音业务需求和第一网络的网络设备以及终端设备支持第一网络与第二网络间的切换中的至少一个。
在该场景下，终端设备可以通过以下方式一和方式二中的任意一种方式进行网络切换。
方式一、通过通知会话管理网元语音业务的用户面隧道的建立被接受的信息，使得第一网络中的网络设备为终端设备的语音业务建立用户面隧道，在终端设备从第一网络切换至第二网络的过程中，第一网络中的网络设备为终端设备的语音业务建立的用户面隧道将切换为第二网络中的语音业务的用户面隧道。
参见图8，方式一具体可以包括：
S11、第一接入网设备向会话管理网元发送第二会话管理信息，第二会话管理信息包括语音业务的用户面隧道的建立被接受的信息。
具体的，第一接入网设备可以将第二会话管理信息携带在N2会话响应(N2 session response)中向第一移动性管理网元发送，第一移动性管理网元再将第二会话管理信息携带在携带有PDU会话修改命令的会话管理响应(session management with PDU modification command ack)中向会话管理网元发送。
需要说明的是，由于第一网络无法进行语音业务，因此，虽然第二会话管理信息包括语音业务的用户面隧道的建立被接受的信息，但是实际上，第一接入网设备并未给语音业务分配无线资源。
可选的，参见图8，在步骤S11之前，该方法还可以包括：第一接入网设备根据第一会话管理信息和第一条件确定不为语音业务的用户面隧道分配无线资源。
S12、会话管理网元接收第一接入网设备发送的第二会话管理信息，根据第二会话管理信息确定语音业务的用户面隧道相关信息。
具体的，终端设备的语音业务的用户面隧道相关信息具体可以为语音业务的用户面隧道相关的数据检测(packet detection)、执行策略(enforcement rule)、上报策略(reporting rule)、核心网隧道信息(core network tunnel information)等。
S13、会话管理网元向用户面网关发送语音业务的用户面隧道相关信息。
其中，用户面网关可以为UPF+PGW-U功能网元。
SMF+PGW-C功能网元可以将语音业务的用户面隧道相关信息携带在N4会话修改请求(N4 session modification request)中向UPF+PGW-U功能网元发送。
S14、用户面网关接收会话管理网元发送的语音业务的用户面隧道相关信息，并根据语音业务的用户面隧道相关信息为语音业务建立用户面隧道。
步骤S11-S14可以在步骤702之前执行，也可以在步骤702之后、语音业务的用户面隧道开 始切换之前执行，则通过语音业务的用户面隧道的切换可以将用户面网关为语音业务建立的用户面隧道也切换成第二网络中的语音业务的用户面隧道，从而使得终端设备可以在第二网络中进行语音业务。
方式二、通过通知会话管理网元语音业务的用户面隧道的建立被拒绝的原因信息，使得会话管理网元在终端设备完成第一网络至第二网络的切换后为终端设备的语音业务重新建立用户面隧道。
参见图9，方式二具体可以包括：
S21、第一接入网设备向会话管理网元发送第三会话管理信息，第三会话管理信息包括终端设备的语音业务的用户面隧道的建立被拒绝的原因信息。
具体的，NG RAN可以将第三会话管理信息携带在N2会话响应中向AMF发送，AMF再将第三会话管理信息携带在携带有PDU会话修改命令的会话管理响应中向SMF+PGW-C功能网元发送。
可选的，拒绝的原因信息可以为：终端设备在执行切换流程。
S22、会话管理网元接收第一接入网设备发送的第三会话管理信息。
S23、会话管理网元确定终端设备从第一网络切换至第二网络。
步骤S23在具体实现时可以通过方式(1)和方式(2)中的任意一种方式实现，方式(1)为在会话管理网元中设置一个定时器，当定时器超时后，确定终端设备从第一网络切换至第二网络，方式二为当接收到隧道修改请求(modify bearer request)，会话管理网元确定终端设备从第一网络切换至第二网络，隧道修改请求用于修改终端设备的语音业务的信令面隧道信息。
S24、会话管理网元根据原因信息在第二网络为语音业务建立用户面隧道。
步骤S24在具体实现时，当会话管理网元确定第三会话管理信息为原因信息或者原因信息为终端设备在执行切换流程时，可以在终端设备从第一网络切换至第二网络后，在第二网络为语音业务建立用户面隧道。
在方式二中，虽然第一网络中的网络设备并未为语音业务建立用户面隧道，但是通过使得会话管理网元在确定终端设备从第一网络切换至第二网络后，在第二网络为终端设备的语音业务建立用户面隧道，从而使得终端设备可以在第二网络中进行语音业务。
方式二提供了一种第一网络无法进行语音业务但是第二网络可以进行语音业务的场景下终端设备切换网络的方法，第一接入网设备在接收到第一会话管理信息时，能及时切换第一网络中的终端设备至第二网络，以便第一网络中的终端设备在第二网络继续执行语音呼叫建立流程，同时第一接入网设备以终端设备在执行切换流程为原因信息拒绝语音业务的用户面隧道的建立，以触发用户面网关在终端设备成功切换至第二网络后重建语音业务的用户面隧道(由于该场景下，第二网络可以进行语音会话，从而该用户面隧道可以建立成功)，从而使得终端设备在第二网络进行语音业务。
场景二、第一网络和第二网络均无法进行语音业务。
在该场景下，第一条件还可以包括：第二网络无法进行语音业务。
在该场景下，终端设备可以通过以下方式三和方式四中的任意一种方式进行网络切换。
方式三、通过通知会话管理网元语音业务的用户面隧道的建立被拒绝的原因信息，使得会话管理网元在终端设备完成第一网络至第二网络的切换后为终端设备的语音业务重新建立用户面隧道，用户面隧道建立不成功时，使得终端设备回落至2G/3G网络中进行语音业务。
方式三具体可以包括：
S31-S34。
步骤S31-S34与步骤S21-S24分别对应相同，即步骤S31与步骤S21相同，步骤S32与步骤S22相同，步骤S33与步骤S23相同，步骤S34与步骤S24相同。具体可参见图9。
步骤S34在具体实现时，用户面隧道建立的过程具体可以通过以下过程P1至P4中的任意一 个过程实现。
参见图10，过程P1可以包括：
(11)、服务网关向第二移动性管理网元发送隧道建立请求(creat bearer request)，隧道建立请求用于请求为终端设备建立语音业务的用户面隧道。
其中，服务网关可以为SGW，第二移动性管理网元可以为MME，语音业务的用户面隧道可以为QCI＝1(QCI是指业务质量等级标识，英文全称为qos class identifier)的专有承载。
(12)第二移动性管理网元接收服务网关发送的隧道建立请求，并根据第二条件向服务网关发送隧道建立响应(creat bearer response)。
其中，隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息。
第二条件包括第二网络无法进行语音业务，第二条件还可以包括终端设备为从第一网络切换至第二网络的终端设备。
具体的，当第二移动性管理网元确定第二条件成立时，第二移动性管理网元拒绝为语音业务建立用户面隧道，并将该信息包含在隧道建立响应中向服务网关发送。
步骤(12)之后，服务网关可以将语音业务的用户面隧道建立被拒绝的信息通过会话管理网元、策略控制功能网元告知IMS网元，以便IMS网元触发终端设备的电路域交换回落(circuit switched fallback，简称CSFB)业务。IMS网元可以为P-CSCF。
参见图11，过程P2可以包括：
(21)、服务网关向第二移动性管理网元发送隧道建立请求，隧道建立请求用于请求为终端设备建立语音业务的用户面隧道。
(22)、第二移动性管理网元向第二接入网设备发送无线隧道建立请求(bearer setup request)，无线隧道建立请求用于请求为终端设备的语音业务建立用户面隧道。
其中，第二接入网设备可以为eNB，语音业务的用户面隧道可以是QCI＝1的专有承载。
(23)、第二接入网设备接收第二移动性管理网元发送的无线隧道建立请求，并根据第二条件向第二移动性管理网元发送无线隧道建立响应(bearer setup response)。
其中，无线隧道建立响应包括语音业务的用户面隧道建立被拒绝的信息。第二条件包括第二网络无法进行语音业务，第二条件还可以包括终端设备为从第一网络切换至第二网络的终端设备。
具体的，当第二接入网设备确定第二条件成立时，第二接入网设备拒绝为语音业务建立用户面隧道，并将该信息包含在无线隧道建立响应中向第二移动性管理网元发送。
(24)第二移动性管理网元接收第二接入网设备发送的无线隧道建立响应并根据第二条件向服务网关发送隧道建立响应。
其中，隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息。
步骤(24)之后，服务网关可以将语音业务的用户面隧道建立被拒绝的信息通过会话管理网元、策略控制功能网元告知IMS网元，以便IMS网元触发终端设备的CSFB业务。
其中，策略控制功能网元可以为PCF+PCRF功能网元。
参见图12，过程P3可以包括：
(31)、服务网关向第二移动性管理网元发送隧道建立请求，隧道建立请求用于请求为终端设备建立语音业务的用户面隧道。
(32)、第二移动性管理网元接收服务网关发送的隧道建立请求并向第二接入网设备发送无线隧道建立请求，无线隧道建立请求用于请求为终端设备的语音业务建立用户面隧道。
(33)第二接入网设备接收第二移动性管理网元发送的无线隧道建立请求，并根据第二条件向第二移动性管理网元发送无线隧道建立响应。
其中，无线隧道建立响应包括语音业务的用户面隧道建立被拒绝的信息。第二条件包括第二网络无法进行语音业务，第二条件还可以包括终端设备为从第一网络切换至第二网络的终端设备。
具体的，当第二接入网设备确定第二条件成立时，第二接入网设备拒绝为语音业务建立用户 面隧道，并将该信息包含在无线隧道建立响应中向第二移动性管理网元发送。
(34)第二移动性管理网元接收第二接入网设备发送的无线隧道建立响应并根据无线隧道建立响应向服务网关发送隧道建立响应。
无线隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息，隧道建立响应包括终端设备的语音业务的用户面隧道建立被拒绝的信息。
步骤(34)之后，服务网关可以将语音业务的用户面隧道建立被拒绝的信息通过会话管理网元、策略控制功能网元告知IMS网元，以便IMS网元触发终端设备的CSFB业务。
由于该场景下，第二网络无法进行语音会话，因此，语音业务的用户面隧道无法建立成功。该情况下，可以使得终端设备回落至2G/3G网络中进行语音业务，则需要终端设备进行CSFB业务，而联合注册是终端设备后续发起CSFB呼叫的必要前提条件，终端设备完成联合注册是指终端设备完成EPS和CS域的联合注册流程。因此，为了保证终端设备成功发起CSFB呼叫，需要使得终端设备完成联合注册之后触发终端设备的CSFB业务，具体可以通过以下四种方式W1至W4中的任意一种方式实现。
方式W1：
参见图10，在过程P1中，第二移动性管理网元确定终端设备完成了联合注册之后再执行步骤(12)，具体的，当第二移动性管理网元确定接收到来自终端设备的联合注册完成消息，联合注册完成消息具体可以为跟踪区更新完成(tracking area update complete)消息，第二移动性管理网元确定终端设备完成了联合注册。
参见图11，在过程P2中，在步骤(24)中，第二移动性管理网元确定第二条件成立且终端设备完成联合注册后，第二移动性管理网元向服务网关发送隧道建立响应。具体的，当第二移动性管理网元确定接收到来自终端设备的联合注册完成消息，第二移动性管理网元确定终端设备完成了联合注册。
参见图12，在过程P3中，若第二条件成立，第二移动性管理网元确定终端设备完成联合注册之后再执行步骤(32)。具体的，当第二移动性管理网元确定接收到来自终端设备的联合注册完成消息，第二移动性管理网元确定终端设备完成了联合注册。
在该方式中，由于IMS网元是在收到语音业务的用户面隧道建立被拒绝的信息之后触发终端设备的CSFB业务，第二移动性管理网元在确定终端设备完成了联合注册之后再向服务网关发送隧道建立响应，从而使得IMS网元是在终端设备完成了联合注册之后触发终端设备的CSFB业务，从而保证终端设备成功发起CSFB呼叫。
方式W2：
步骤S34在具体实现时，会话管理网元根据原因信息和第二条件在第一预设时间段后在第二网络为语音业务建立用户面隧道。
具体可以通过方式m1和方式m2实现。
方式m1为：会话管理网元根据原因信息和第二条件在第一预设时间段后向第二网络的服务网关发送隧道建立请求，隧道建立请求用于请求建立语音业务的用户面隧道。
具体的，第一预设时间段的起始时间点可以为接收到原因信息的时间点。
方式m2为：会话管理网元根据原因信息向第二网络的服务网关发送隧道建立请求，隧道建立请求用于请求建立语音业务用户面隧道；会话管理网元接收服务网关发送的隧道建立响应，隧道建立响应中包括语音业务的用户面隧道建立被拒绝的信息；会话管理网元根据第二条件在第一预设时间段后向策略功能控制网元发送第一消息，第一消息用于指示语音业务的用户面隧道建立失败。其中，第一消息可以为信用控制请求(credit control request，简称CCR)，用户面隧道建立失败的信息可以包含在CCR中。
具体的，第一预设时间段的起始时间点可以为接收到原因信息的时间点。
在该方式中，认为IMS网元延迟第一预设时间段触发终端设备的CSFB业务时，终端设备已 经完成了联合注册，具体可以通过使得会话管理网元延迟第一预设时间段发送隧道建立请求或第一消息使得IMS网元延迟第一预设时间段触发终端设备的CSFB业务，从而保证终端设备成功发起CSFB呼叫。
方式W3：
参见图13，方式W3可以包括：
W3-1、IMS网元接收为终端设备在分组交换(packet switching，简称PS)域建立语音业务的请求消息。
该请求消息具体可以为邀请(invite)消息。
W3-2、IMS网元确定无法在第一网络或第二网络的PS域建立语音业务。
W3-3、IMS网元确定终端设备完成联合注册。
W3-4、IMS网元触发终端设备的CSFB业务。
该方式中，由IMS网元确定终端设备完成联合注册之后，再触发终端设备的CSFB业务，从而保证终端设备成功发起CSFB呼叫。
可选的，在步骤W3-1之后，该方法还可以包括：IMS网元根据在分组交换域建立语音业务的请求消息，确定终端设备注册于第一网络，进而确定是在第一网络接收到该请求消息。
可选的，W3-2具体可以包括：IMS网元获取来自第一网络PS域的语音业务建立失败信息，具体的，IMS网元在接收语音业务的用户面隧道建立失败的信息时，通过确定终端设备注册于第一网络判定语音业务的用户面隧道建立失败的信息是来自于第一网络的PS域；或，IMS网元获取来自第二网络PS域的语音业务建立失败信息，具体的，IMS网元在接收语音业务的用户面隧道建立失败的信息时，通过确定终端设备注册于第二网络判定语音业务的用户面隧道建立失败的信息是来自于第二网络的PS域。
语音业务建立失败信息可以由其他网络设备向IMS网元上报。
可选的，W3-3具体可以包括：IMS网元确定无法在第一网络或第二网络的PS域建立语音业务起的第二预设时间段后，IMS网元确定终端设备完成联合注册；或者，IMS网元根据从策略控制网元或归属用户服务器(home subscriber server，简称HSS)获得的终端设备的注册位置信息，确定终端设备完成联合注册。
具体的，策略控制网元或归属用户服务器可以主动将终端设备的注册位置信息向IMS网元上报，也可以由IMS网元从策略控制网元或归属用户服务器中查询。
当终端设备为语音业务的主叫终端设备时，W3-4具体可以包括：IMS网元向主叫终端设备发送第二消息，第二消息用于触发主叫终端设备发起CSFB主叫语音业务。
当终端设备为语音业务的被叫终端设备，W3-4具体可以包括：IMS网元向被叫域选设备发送第三消息，第三消息用于指示在第一网络或第二网络的PS域的被叫语音业务建立失败，以使被叫域选设备触发被叫终端设备的CSFB被叫语音业务。
第二消息和第三消息可以为500响应消息或380响应消息或503响应消息。
方式四、第一接入网设备通知会话管理网元语音业务的用户面隧道的建立被拒绝的信息，若被拒绝的信息包括无线资源不足(或资源分配失败)，会话管理网元在终端设备完成第一网络至第二网络的切换后并不为终端设备的语音业务建立用户面隧道，用户面隧道建立不成功信息通过第一网络传输给IMS网络，从而使得IMS网络触发终端设备的CSFB业务。
方式四具体包括：第一接入网设备向会话管理网元发送第四会话管理信息，第四会话管理信息包括语音业务的用户面隧道的建立被拒绝的信息，语音业务的用户面隧道的建立被拒绝的信息包括无线资源不足。
该方式中，会话管理网元在终端设备从第一网络切换至第二网络后，不为终端设备的语音业务重新建立用户面隧道，而是通过在切换流程做改进，从而保证终端设备成功发起CSFB呼叫，具体可以通过上述W3、以及以下方式W4至W8中的任意一种方式实现，其中，W5和W6针对 终端设备为主叫终端设备的情况。
方式W4：
参见图14，方式W4包括：
W4-1、第二移动性管理网元接收第一移动性管理网元发送的第四消息，第四消息用于确认终端设备完成重定位。
第四消息具体可以为重定位请求完成响应(relocatioon request complete acknowledge)消息，这里的重定位是指终端设备从第一网络切换至第二网络流程中，终端设备对应的移动性管理网元发生重定位，从第一移动性管理网元重定位成第二移动性管理网元。
W4-2、第二移动性管理网元确定第二条件成立且终端设备完成联合注册。
第二条件包括第二网络无法进行语音业务，第二条件还可以包括终端设备为从第一网络切换至第二网络的终端设备。
W4-3、第二移动性管理网元向服务网关发送隧道修改请求，隧道修改请求用于请求修改终端设备的语音业务的信令面隧道信息。
服务网关接收隧道修改请求后，向会话管理网元发送隧道修改请求，会话管理网元进而向用户面网关发送隧道修改请求，以便用户面网关根据语音业务的信令面隧道信息建立相应的语音业务的信令面隧道。这里的语音业务的信令面隧道具体可以是QCI＝5的专用承载。
需要说明的是，IMS网元在获知用户面隧道建立失败后，可以向终端设备发送第二消息(第二消息的含义与上文中提及的相同)，该第二消息是需要经过语音业务的信令面隧道(即QCI＝5的专有承载)传输给终端设备的，用户面网关会在接收到隧道修改请求并完成语音业务的信令面隧道的建立后，将第二消息通过信令面隧道向终端设备发送。在该方式中，第二移动性管理网元在确定终端设备完成了联合注册之后才向服务网关发送隧道修改请求，从而保证终端设备成功发起CSFB呼叫。
方式W5：
参见图15，方式W5包括：
W5-1、MME确定终端设备完成了联合注册。
W5-2、IMS网元确定无法在第一网络或第二网络的PS域建立语音业务。
W5-3、IMS网元向终端设备发送第二消息。
方式W5中的各个步骤的实现方法可以参见上文，在此不再赘述。
该方式中，MME确定终端设备完成了联合注册之后，IMS网元才向终端设备发送的第二消息，因此，可以保证终端设备成功发起CSFB呼叫。
方式W6：
参见图16，方式W6包括：
W6-1、IMS网元确定无法在第一网络或第二网络的PS域建立语音业务。
W6-2、IMS网元向用户面网关发送第二消息。
W6-3、用户面网关缓存第二消息。
W6-4、MME确定终端设备完成了联合注册。
W6-5、MME向用户面网关发送隧道修改请求。
W6-6、用户面网关接收到隧道修改请求后向终端设备发送第二消息。
方式W6中的各个步骤的实现方法以及相关名词的含义可以参见上文，在此不再赘述。
该方式中，用户面网关先缓存IMS网元发送的第二消息，在接收到隧道修改请求后向终端设备发送第二消息，由于隧道修改请求是在MME确定终端设备完成了联合注册之后向用户面网关发送的，因此，可以保证终端设备成功发起CSFB呼叫。
方式W7：
参见图17，方式W7包括：
W7-1、IMS网元确定无法在第一网络或第二网络的PS域建立所述语音业务。
W7-2、当终端设备为主叫终端设备时，所述IMS网元延迟第二预设时间段向终端设备发送第二消息；当终端设备为被叫终端设备时，所述IMS网元延迟第二预设时间段向被叫域选设备发送第三消息。
方式W7中的各个步骤的实现方法以及相关名词的含义可以参见上文，在此不再赘述。
在该方式中，认为IMS网元延迟第二预设时间段触发终端设备的CSFB业务时，终端设备已经完成了联合注册，从而保证终端设备成功发起CSFB呼叫。
上述第一预设时间段和第二预设时间段可以根据实际的网络情况进行预设，第一预设时间段和第二预设时间段可以相同也可以不同，例如，第一预设时间段可以为500ms，第二预设时间段可以为100ms。
需要说明的是，5G网络并未像2G/3G网络那样部署专门的CS域，因此无法为终端设备提供类似于传统语音的CS语音业务，通过方式三和方式四，本申请实施例提供的方法还可以使得终端设备在无法进行IMS语音业务的情况下，进行CS语音业务。
本申请还提供了下述4个实施例，用于对上述方法进行示例性说明，其中，实施例(1)和实施例(2)的应用场景均为5G网络无法进行IMS语音业务但EPS网络可进行IMS语音业务的场景，实施例(3)和实施例(4)的应用场景均为5G网络无法进行IMS语音业务并且EPS网络也无法进行IMS语音业务的场景。在每个实施例中又可以分为主叫侧和被叫侧，若无特别说明，描述主叫侧的方法中的UE以及各个网元均指主叫侧的UE和网元，描述被叫侧的方法中的UE以及各个网元均指被叫侧的UE和网元。
实施例(1)
该实施例提供了一种主叫UE进行网络切换的方法，参见图18，该方法包括：
1801、UE向P-CSCF发送邀请消息，邀请消息用于请求建立IMS语音业务。
该UE为5G网络中的UE，该邀请消息为用于请求为5G网络的UE在PS域建立语音业务的消息。
1802、P-CSCF根据接收到的UE发送的邀请消息为UE建立IMS语音会话。
P-CSCF还会将邀请消息发往后续的主叫IMS网络中的节点(例如S-CSCF和TAS等IMS节点)，后续的IMS网络中的节点开始处理接收到的邀请消息，被叫UE可能接收到被叫IMS网络转发的主叫UE的邀请消息。
1803、P-CSCF向PCF+PCRF发送鉴权授权请求(authentication authorization request，简称AAR)以触发UE的IMS语音业务的用户面隧道的建立。
AAR可携带UE的用户标识、IMS应用层计费标识和IMS语音业务的媒体描述信息等，媒体描述信息可包括如下信息的至少一种：分类器标识、带宽要求描述信息、媒体类型描述信息和QoS参数。
需要说明的是，P-CSCF可以直接向PCF+PCRF发送AAR，也可以在接收到IMS网络中的S-CSCF发送的183响应消息之后向PCF+PCRF发送AAR。
1804、PCF+PCRF根据P-CSCF发送的AAR中携带的媒体描述信息向SMF+PGW-C发送分组数据单元-连接接入网络(packet data unit-connectivity access network，简称PDU-CAN)会话修改(session modification)流程请求以触发5G网络中的网元为UE的IMS语音业务建立用户面隧道。
PDU-CAN会话修改携带QoS规则(rules)，QoS规则包括QoS参数集合(profile)以及数据包过滤器(packet filter)等，QoS参数集合通常又由以下QoS关键参数中的一个或多个组成：GBR、ARP、5QI和MBR等。
通常来说，5G网络中用户面隧道通常是指用于传输用户面数据的QoS flow，IMS语音业务的用户面隧道的5QI可以等于1，也可以为其他值，本申请实施例中以IMS语音业务的用户面隧道的5QI＝1为例对本申请实施例提供的方法进行示例性说明。
1805、SMF+PGW-C在接收到PCF+PCRF网元发送的PDU-CAN会话修改流程请求后，向AMF发送携带有PDU会话修改命令的会话管理请求，该请求中包含第一SM信息，第一SM信息为与UE的IMS语音业务的用户面隧道相关的SM信息，第一SM信息中可以包含用户面隧道的QoS参数，例如，5QI＝1，以及ARP、GBR和MBR等参数，第一SM信息中还可以包括其他信息。
1806、AMF根据接收到的SMF+PGW-C发送的第一SM信息向NG RAN发送N2会话请求，其中透传第一SM信息给NG RAN，以便NG RAN根据第一SM信息为5QI＝1的用户面隧道分配对应的无线资源。
1807、NG RAN根据第一SM信息和第一条件确定不为UE的IMS语音业务的用户面隧道分配无线资源。
需要说明的是，步骤1807可以执行也可以不执行，本申请实施例对此不作具体限定。
第一条件可以包括以下条件：(1)5G网络无法进行IMS语音业务，该条件表示5G网络并未部署IMS语音业务，或者当前5G网络信号覆盖差不足以满足IMS语音业务的要求；(2)EPS网络支持语音业务，该条件可以由运营商作为本地策略配置在NG RAN上；(3)EPS网络的信号质量满足语音业务需求，NG RAN可以通过指示UE去测量并上报周边EPS小区的信号质量确定EPS网络的信号质量是否满足语音业务需求；(4)5G网络的网络设备(AMF、NG RAN等)和UE支持5G网络与EPS网络间的切换，其中，UE和AMF是否支持5G网络与EPS网络间的切换，可以由AMF在UE从空闲(idle)态变为连接(connected)态时通过N2消息告知NG RAN。
1808、NG RAN向AMF发送N2会话响应(N2 session response)。
N2会话响应中包括第二SM信息，第二SM信息包括UE的IMS语音业务的用户面隧道的建立被接受的信息。
1809、AMF根据接收到的N2会话响应向SMF+PGW-C发送携带有PDU会话修改命令的会话管理响应，其中向SMF+PGW-C透传第二SM信息。
1810、SMF+PGW-C根据接收到的AMF发送的携带有PDU会话修改命令的会话管理响应向UPF+PGW-U发送N4会话修改请求。这里的N4是指SMF+PGW-C和UPF+PGW-U之间是N4接口，但是本申请实施例并不限定该接口名称，也即不限定该消息名称为N4会话修改请求。
N4会话修改请求中携带5QI＝1的用户面隧道相关的数据检测(packet detection)、执行策略(enforcement rule)、上报策略(reporting rule)、核心网隧道信息(CN tunnel information)等，以便UPF+PGW-U能够为5QI＝1的用户面隧道建立相应的核心网隧道。
1811、UPF+PGW-U接收SMF+PGW-C发送的N4会话修改请求，并根据N4会话修改请求为5QI＝1的用户面隧道建立相应的核心网隧道。
需要说明的是，5G网络中用户面隧道通常是指用于传输用户面数据的QoS flow，而EPS网络中用户面隧道通常是指用于传输用户面数据的承载(bearer)。UPF+PGW-U为5QI＝1的用户面隧道建立相应的用户面隧道之后，在UE从5G网络切换至EPS网络的过程中，会将该用户面隧道也进行切换，也即从5QI＝1的QoS flow切换成QCI＝1的专用承载。具体的，SMF+PGW-C可以通过接收到的SGW发送的隧道修改请求判断UE的5QI＝1的用户面隧道已经从5G网络切换成EPS网络的QCI＝1的用户面隧道，并且QCI＝1的用户面隧道已经建立成功。UE从5G网络切换到EPS网络后，UE收到EPS网络转发的IMS语音业务的相关信令后，UE在EPS网络继续后续的IMS语音呼叫建立流程，从而完整地建立IMS语音会话。
在步骤1811之后，UPF+PGW-U还会向SMF+PGW-C发送N4会话修改响应，SMF+PGW-C会向PCF+PCRF发送PDU-CAN会话修改，PCF+PCRF会向P-CSCF发送重认证请求(Re-authentication Request，简称RAR)，P-CSCF会向PCF+PCRF发送信用重授权应答(re-authentication answer，简称RAA)，由此P-CSCF可知IMS语音业务的用户面隧道建立成功。
1812、NG RAN根据接收到的第一SM信息和第一条件向AMF发送切换请求以触发UE从5G网络切换至EPS网络。
具体的，在第一条件成立时，当NG RAN根据第一SM信息确定有一个5QI＝1的用户面隧道需要建立时，即可向AMF发送切换请求。
UE从5G网络切换至EPS网络的切换流程可以参见标准协议，在此不再赘述。UE从5G网络切换到EPS网络后，UE收到EPS网络转发的IMS语音业务的相关信令后，UE在EPS网络继续后续的IMS语音呼叫建立流程，从而完整地建立IMS语音会话。
该实施例还提供了一种被叫UE进行网络切换的方法，参见图19，该方法包括：
1901、P-CSCF接收S-CSCF发送的邀请消息，并根据邀请消息为UE建立IMS语音会话。
该邀请消息为用于请求为5G网络的UE在PS域建立语音业务的消息。
1902、P-CSCF向UE发送邀请消息。
1903、UE接收P-CSCF发送的邀请消息并向P-CSCF回复183响应消息。
1904、P-CSCF接收UE发送的183响应消息，并向S-CSCF发送183响应消息。
S-CSCF可进一步向主叫方S-CSCF发送183响应消息，主叫方S-CSCF进一步向主叫方P-CSCF发送183响应消息，主叫方P-CSCF若收到主叫方S-CSCF发送的183响应消息，可向主叫UE转发183响应消息。
1905-1914。
步骤1905-1914与步骤1803-1812分别对应相同，即步骤1905与步骤1803相同，步骤1906与步骤1804相同，依次类推，步骤1914与步骤1812相同，下文中的类似描述含义相同。
上述实施例(1)提供了一种5G网络无法进行IMS语音业务但是EPS网络可以进行IMS语音业务的场景下终端设备切换网络的方法，NG RAN在接收5QI＝1的用户面隧道建立请求时，能及时切换5G终端至EPS网络，以便5G中的终端设备在EPS网络继续执行IMS语音呼叫建立流程。
实施例(2)
该实施例提供了一种主叫UE进行网络切换的方法，参见图20，该方法包括：
2001-2006。
步骤2001-2006与步骤1801-1806分别对应相同。
2007、NG RAN根据第一SM信息和第一条件向AMF发送N2会话响应。
NG RAN根据第一SM信息可以确定请求建立的是IMS语音业务的用户面隧道，具体为5QI＝1的用户面隧道。
N2会话响应中包括第三SM信息，第三SM信息可以包含表明NG RAN拒绝为5QI＝1的用户面隧道分配无线资源的SM信息，并且携带拒绝的原因信息，原因信息为UE在执行切换流程，更进一步，原因信息可以为UE正在执行5G网络至EPS网络的切换，以便SMF+PGW-C根据该原因信息决定在UE的切换流程结束后，重新发起UE的IMS语音业务的用户面隧道的建立。
第一条件可以包括以下条件：(1)5G网络无法进行IMS语音业务，该条件表示5G网络并未部署IMS语音业务，或者当前5G网络信号覆盖差不足以满足IMS语音业务的要求；(2)EPS网络支持语音业务，该条件可以由运营商作为本地策略配置在NG RAN上；(3)EPS网络的信号质量满足语音业务需求，NG RAN可以通过指示UE去测量并上报周边EPS小区的信号质量确定EPS网络的信号质量是否满足语音业务需求；(4)5G网络的网络设备(AMF、NG RAN等)和UE支持5G网络与EPS网络间的切换，其中，UE和AMF是否支持5G网络与EPS网络间的切换，可以由AMF在UE从空闲态变为连接态时通过N2消息告知NG RAN。
2008、AMF根据接收到的N2会话响应向SMF+PGW-C发送携带有PDU会话修改命令的会话管理请求，其中向SMF+PGW-C透传第三SM信息。
2009、SMF+PGW-C根据接收到的AMF发送的携带有PDU会话修改命令的会话管理请求中的第三SM信息，确定在UE从5G网络切换至EPS网络后在EPS网络重新为UE的IMS语音业务建立用户面隧道。
需要说明的是，在EPS网络重新为UE的IMS语音业务建立用户面隧道指的是QCI＝1的用户面隧道的建立。
在UE从5G网络切换至EPS网络的过程中，SMF+PGW-C可以通过接收到的SGW发送的隧道修改请求判断UE已经成功从5G网络切换到了EPS网络。另外，SMF+PGW-C还可以通过设置定时器，从接收到第三SM信息开始触发定时器计时，定时器计时结束则判断UE已经成功从5G网络切换到了EPS网络。
2010、NG RAN根据接收到的第一SM信息和第一条件向AMF发送切换请求以触发UE从5G网络切换至EPS网络。
具体的，在第一条件成立时，当NG RAN根据第一SM信息确定有一个5QI＝1的用户面隧道需要建立时，即可向AMF发送切换请求。
UE从5G网络切换至EPS网络的切换流程可以参见标准协议，在此不再赘述。
2011、SMF+PGW-C在UE切换完成后，向SGW发送隧道建立请求(create bearer quest)以触发QCI＝1的用户面隧道的建立。
后续，QCI＝1的用户面隧道在EPS网络成功建立，且EPS网络向IMS网络反馈IMS语音业务的用户面隧道建立成功，QCI＝1的用户面隧道建立流程和IMS语音会话在EPS网络的建立流程具体见标准协议，此处不再赘述。
该实施例还提供了一种被叫UE进行网络切换的方法，参见图21，该方法包括：
2101-2113。
其中，步骤2101-2104与步骤1901-1904分别对应相同，步骤2105-2113与步骤2003-2111分别对应相同。
上述实施例(2)提供了一种5G网络无法进行IMS语音业务但是EPS网络可以进行IMS语音业务的场景下终端设备切换网络的方法，NG RAN在接收5QI＝1的用户面隧道建立请求时，能及时切换5G终端至EPS网络，以便5G中的终端设备在EPS网络继续执行IMS语音呼叫建立流程，同时NG RAN以切换正在进行为原因信息拒绝5QI＝1的用户面隧道的建立，以触发核心网网关在UE成功切换至EPS网络后重建QCI＝1的用户面隧道。
实施例(3)
该实施例提供了一种主叫UE进行网络切换的方法，参见图22，该方法包括：
2201-2210。
步骤2201-2210与步骤2001-2010分别对应相同。
2211、SMF+PGW-C在UE切换完成后，向SGW发送隧道建立请求以触发QCI＝1的用户面隧道的建立。
2212、SGW向MME转发隧道建立请求。
步骤2212之后，MME接收隧道建立请求并执行以下过程中的过程一(包括a1)、过程二(包括b1-b4)和过程三(包括c1-c4)中的任意一个过程。
过程一：
a1、MME根据第二条件向SGW发送隧道建立响应，隧道建立响应包括UE的语音业务的用户面隧道建立被拒绝的信息。
过程一中，第二条件可以包括第二网络无法进行语音业务，还可以包括UE为从5G网络切换至EPS网络的UE和UE完成了联合注册中的至少一个，其中第二网络无法进行语音业务具体地可以是指无法进行IMS语音业务，UE完成了联合注册是指UE完成EPS和CS域的联合注册流程。
具体的，MME可以根据接收到的UE发送的注册完成消息确定UE完成了联合注册。
在a1之前，MME可以为IMS语音业务向eNB发送无线隧道建立请求并接收响应消息，也可以不发送无线隧道建立请求和接收响应消息，此处不做限定。
过程二：
b1、MME向eNB发送无线隧道建立请求，无线隧道建立请求用于请求为UE的IMS语音业务建立用户面隧道，具体地，IMS语音业务的用户面隧道可以是指QCI＝1的专有承载。
b2、eNB接收无线隧道建立请求，根据第二条件向MME发送无线隧道建立响应，无线隧道建立响应包括UE的IMS语音业务的用户面隧道建立被拒绝的信息。
过程二中，第二条件包括第二网络无法进行IMS语音业务，还可以包括UE为从5G网络切换至EPS网络的UE。
b3、MME接收eNB发送的无线隧道建立响应，若第二条件成立，MME确定UE完成联合注册。
无线隧道建立响应包括UE的IMS语音业务的用户面隧道建立被拒绝的信息。
具体的，步骤b3在具体实现时，当MME确定接收到UE发送的注册完成消息时，MME确定UE完成联合注册。
b4、MME向SGW发送隧道建立响应，隧道建立响应包括UE的IMS语音业务的用户面隧道建立被拒绝的信息。
过程三：
c1、若第二条件成立，MME确定UE完成联合注册。
具体的，步骤c1在具体实现时，当MME确定接收到UE发送的注册完成消息时，MME确定UE完成联合注册。
过程三中，第二条件包括第二网络无法进行IMS语音业务，还可以包括UE为从5G网络切换至EPS网络的UE。
c2、MME向eNB发送无线隧道建立请求，无线隧道建立请求用于请求为UE的IMS语音业务建立用户面隧道。
c3、eNB接收MME发送的无线隧道建立请求，根据第二条件向MME发送无线隧道建立响应，无线隧道建立响应包括UE的IMS语音业务的用户面隧道建立被拒绝的信息。
c4、MME接收eNB发送的无线隧道建立响应，根据无线隧道建立响应向SGW发送隧道建立响应，隧道建立响应包括UE的IMS语音业务的用户面隧道建立被拒绝的信息。
2213、SGW接收MME发送的隧道建立响应，并向SMF+PGW-C发送隧道建立响应。
2214、SMF+PGW-C向PCF+PCRF发送CCR。
CCR携带用于说明QCI＝1的用户面隧道建立失败的指示，还可以携带隧道建立失败的原因信息，该原因信息具体参考SGW发送的隧道建立响应携带的原因信息来设置。这里CCR还可以被其他名称的消息所取代，此处不做限定，例如IP-CAN会话修改请求。
2215、PCF+PCRF向SMF+PGW-C发送信用控制应答(credit control answer，简称CCA)。
2216、PCF+PCRF根据CCR向P-CSCF发送RAR，RAR可携带用于指示无线资源不足的指示信息(或用于指示资源分配失败的指示信息)。
2217、P-CSCF向PCF+PCRF发送RAA。
2218、P-CSCF根据获取到的无线资源不足的指示信息(或资源分配失败的指示信息)后，确定无法在PS域建立UE的IMS语音业务。
2219、P-CSCF向UE发送500响应消息。
在步骤2219之后，UE接收到P-CSCF发送的500响应消息后，可以重新主叫域选并发起CSFB呼叫，UE侧和网络侧配合执行CSFB流程，最终可能在CS域建立语音呼叫。
在步骤2219之后，若P-CSCF已经接收到183响应消息，P-CSCF可向S-CSCF等IMS网络中的节点发送取消(cancel)消息，用以取消已经请求的IMS语音业务相关呼叫。
需要说明的是，在UE从5G网络切换至EPS网络的过程中，服务UE的移动性管理网元从AMF变换成了MME，因此，MME会为该UE分配一个新的全局唯一的临时标识(globally unique temporary identity，简称GUTI)。参见图22，在切换流程后，UE向MME发送跟踪区更新(tracking  area update，简称TAU)请求，MME在接收到NG RAN发送的TAU请求时，会将所分配的新的GUTI通过TAU接受消息带给UE，以便于UE收到携带新GUTI的TAU接受消息后向MME回复TAU完成消息(即联合注册完成消息)。
在该实施例的上述描述中，MME在确定了UE完成EPS和CS域的联合注册流程之后，才向SGW发送隧道建立响应的目的在于，保证QCI＝1的用户面隧道建立不成功的消息是在UE完成EPS和CS域的联合注册流程之后才到达IMS网络，以便于IMS网络发送的500响应消息可以在UE完成EPS和CS域的联合注册流程之后才到达UE，最终保证UE成功发起CSFB呼叫。
为了保证IMS网络发送的500响应消息可以在UE完成EPS和CS域的联合注册流程之后才到达UE，除了使得MME在确定了UE完成EPS和CS域的联合注册流程之后，才向SGW发送隧道建立响应之外，还可以通过以下方式1至方式5中的任意一种方式实现。
方式1、SMF+PGW-C根据第二条件延迟第一预设时间段向SGW发送隧道建立请求。
在方式1中，第二条件包括EPS网络无法进行IMS语音业务。
方式2、SMF+PGW-C延迟第一预设时间段向PCF+PCRF发送CCR。
方式3、P-CSCF获取到无线资源不足的指示信息或者资源分配失败的指示信息后，延迟一个第二预设时间段向UE发送500响应消息。
方式4、SMF+PGW-C在向PCF+PCRF发送CCR之后，SMF+PGW-C指示UPF+PGW-U缓存发往UE的QCI＝5的用户面隧道上的数据一个第一预设时间段，第一预设时间段过后，UPF+PGW-U可继续向UE发送。
方式5、P-CSCF确定UE完成联合注册之后向UE发送500响应消息。
方式5在具体实现时可以包括：P-CSCF确定无法在5G网络或EPS网络的PS域建立语音业务起的第二预设时间段后，P-CSCF确定终端设备完成联合注册；或者，P-CSCF根据从HSS/归属位置寄存器(home location register，简称HLR)获得的终端设备的注册位置信息，确定终端设备完成联合注册。
其中，第一预设时间段和第二预设时间段可以根据实际的网络通信条件进行设置，例如，第一预设时间段和第二预设时间段均可以为500ms。
该实施例还提供了一种被叫UE进行网络切换的方法，参见图23，该方法包括：
2301-2304。
步骤2301-2304与步骤1901-1904分别对应相同。
2305-2320。
步骤2305-2320与步骤2203-2218分别对应相同。
2321、P-CSCF根据获取到的无线资源不足的指示信息(或资源分配失败的指示信息)后，经S-CSCF向IMS网络中的TAS发送500响应消息，其中，500响应消息具体是发送给TAS中的被叫域选功能模块T-ADS。
2322、P-CSCF获取到无线资源不足的指示信息(或资源分配失败的指示信息)后，向UE发送取消消息，用以取消已经请求的IMS语音业务相关会话。
步骤2321和步骤2322不限定先后关系。
步骤2322之后，IMS网络中的TAS将被叫会话重新域选至CS域，并经S-CSCF等设备向CS域呼叫控制设备(例如移动交换中心(mobile switching center，简称MSC))发起呼叫，CS域呼叫控制设备经SGs接口向MME发起呼叫，MME触发UE的CSFB流程，经UE的CSFB流程，UE可能最终在CS域建立语音会话。具体流程细节见3GPP TS 23.272中的相关描述。此处不再赘述。
在该实施例的上述描述中，MME在确定了UE完成EPS和CS域的联合注册流程之后，才向SGW发送隧道建立响应的目的在于，保证QCI＝1的用户面隧道建立不成功的消息是在UE完成EPS和CS域的联合注册流程之后才到达IMS网络，以便于IMS网络发送的500响应消息可以在 UE完成EPS和CS域的联合注册流程之后才到达TAS，最终保证IMS被叫可以被转化成CSFB被叫到达UE。
为了保证IMS网络发送的500响应消息可以在UE完成EPS和CS域的联合注册流程之后才到达TAS，除了使得MME在确定了UE完成EPS和CS域的联合注册流程之后，才向SGW发送隧道建立响应之外，还可以通过以下方式1至方式5中的任意一种方式实现。
方式1、SMF+PGW-C根据第二条件延迟第一预设时间段向SGW发送隧道建立请求。
在方式1中，第二条件包括EPS网络无法进行IMS语音业务。
方式2、SMF+PGW-C延迟第一预设时间段向PCF+PCRF发送CCR。
方式3、P-CSCF获取到无线资源不足的指示信息(或资源分配失败的指示信息)后，延迟一个第二预设时间段向TAS发送500响应消息。
方式4、SMF+PGW-C在向PCF+PCRF发送CCR之后，SMF+PGW-C指示UPF+PGW-U缓存发往UE的QCI＝5的用户面隧道上的数据(可以为取消消息)一个第一预设时间段，第一预设时间段过后，UPF+PGW-U可继续向UE发送。
方式5、P-CSCF确定UE完成联合注册之后向TAS发送500响应消息。
方式5在具体实现时可以包括：P-CSCF确定无法在5G网络或EPS网络的PS域建立语音业务起的第二预设时间段后，P-CSCF确定终端设备完成联合注册；或者，P-CSCF根据从HSS/HLR获得的终端设备的注册位置信息，确定终端设备完成联合注册。
其中，第一预设时间段和第二预设时间段可以根据实际的网络通信条件进行设置，例如，第一预设时间段和第二预设时间段均可以为500ms。
实施例(4)
该实施例提供了一种主叫UE进行网络切换的方法，参见图24、图25、图26和图27，该方法包括：
2401-2406。
步骤2401-2406与步骤1801-1806分别对应相同。
由于该实施例应用的场景为5G网络无法进行IMS语音业务并且EPS网络也无法进行IMS语音业务的场景，因此，为了保证UE成功发起CSFB呼叫，IMS网络发送的500响应消息需要在UE完成EPS和CS域的联合注册流程之后才到达UE。
为了保证UE成功发起CSFB呼叫，在步骤2406之后，可以通过以下过程1(参见图24)、过程2(参见图25)、过程3(参见图26)和过程4(参见图27)中的任意一个过程完成UE的网络切换。
过程1：
A1、NG RAN根据接收到的第一SM信息和第一条件向AMF发送切换请求以触发UE从5G网络切换至EPS网络。
该情况下，第一条件可以包括以下条件：(1)5G网络无法进行IMS语音业务，该条件表示5G网络并未部署IMS语音业务，或者当前5G网络信号覆盖差不足以满足IMS语音业务的要求；(2)5G网络的网络设备(AMF、NG RAN等)和UE支持5G网络与EPS网络间的切换，其中，UE和AMF是否支持5G网络与EPS网络间的切换，可以由AMF在UE从空闲态变为连接态时通过N2消息告知NG RAN。(3)EPS网络不支持语音业务，该条件可以由运营商作为本地策略配置在NG RAN上；(4)EPS网络的信号质量不满足语音业务需求，NG RAN可以通过指示UE去测量并上报周边EPS小区的信号质量确定EPS网络的信号质量是否满足语音业务需求。
A2、在UE从5G网络切换至EPS网络的过程中，待切换准备流程结束，NG RAN向UE发送切换命令(handover command)。
A3、NG RAN根据第一条件向AMF发送N2会话响应，该N2会话响应携带第四SM信息，第四SM信息包括IMS语音业务的用户面隧道的建立被拒绝的信息，IMS语音业务的用户面隧道 的建立被拒绝的信息包括无线资源不足(或资源分配失败)。
A4、AMF根据接收到的N2会话响应向SMF+PGW-C发送携带有PDU会话修改命令的会话管理响应，其中向SMF+PGW-C透传第四SM信息。
A5、SMF+PGW-C解析第四SM信息后，向PCF+PCRF发送PDU-CAN会话修改消息。
PDU-CAN会话修改消息中包括用于指示IMS语音业务的用户面隧道建立失败的信息，该指示信息可以为无线资源不足的指示信息(或资源分配失败的指示信息)，本实施例中，不限定该消息名称为PDU-CAN会话修改消息，可以是其他消息名称，如CCR等。
A6、PCF+PCRF向P-CSCF发送RAR，RAR可携带用于指示IMS语音业务的用户面隧道建立失败的信息。
A7、P-CSCF根据接收到的用于指示用户面隧道建立失败的信息确定无法在PS域建立IMS语音业务。
A8、P-CSCF向UE发送500响应消息，该消息到达UPF+PGW-U。
其中该500响应消息是经过5G网络的隧道(具体是某QoS flow)传输给UE的。
A9、在UE从5G网络切换至EPS网络的过程中，MME确定UE完成联合注册。
A10、MME通过SGW向SMF+PGW-C发送QCI＝5的用户面隧道的隧道修改请求，用于向SMF+PGW-C指示QCI＝5专有承载的下行的SGW用户面地址和隧道信息。
A11、SMF+PGW-C向UPF+PGW-U发送隧道修改请求，向UPF+PGW-U指示QCI＝5专有承载的下行的SGW用户面地址和隧道信息。此后SMF+PGW-C通过SGW向MME反馈隧道修改响应。
A12、UPF+PGW-U向UE转发QCI＝5专有承载上的用户面数据，即500响应消息被发往UE。
步骤A12之后，UE发起CSFB主叫语音业务，UE侧和网络侧配合执行CSFB流程，最终可能在CS域建立语音呼叫。
由于此时UE已经离开5G网络，接入EPS网络，500响应消息到达UPF+PGW-U之后，将会被UPF+PGW-U通过EPS网络的IMS信令隧道(QCI＝5的用户面隧道)发往UE。若P-CSCF已经接收到183响应消息，P-CSCF可向S-CSCF等IMS网络中的节点发送取消消息，用以取消已经请求的IMS语音业务的相关呼叫。
在过程1中，由于UPF+PGW-U在接收到隧道修改请求之后才会向UE发送500响应消息，通过使得MME在确定UE完成联合注册之后再向SMF+PGW-C进而向UPF+PGW-U发送QCI＝5的用户面隧道的隧道修改请求，从而使得IMS网络发送的500响应消息在UE完成EPS和CS域的联合注册流程之后才到达UE，为UE成功发起CSFB呼叫提供了保证。
过程2：
B1、NG RAN根据第一条件向AMF发送N2会话响应，N2会话响应携带第四SM信息，第四SM信息包括IMS语音业务的用户面隧道的建立被拒绝的信息，IMS语音业务的用户面隧道的建立被拒绝的信息包括无线资源不足(或资源分配失败)。
具体的，NG RAN可以根据第一条件确定第四SM信息。
该情况下，第一条件可以包括以下条件：(1)5G网络无法进行IMS语音业务，该条件表示5G网络并未部署IMS语音业务，或者当前5G网络信号覆盖差不足以满足IMS语音业务的要求；(2)5G网络的网络设备(AMF、NG RAN等)和UE支持5G网络与EPS网络间的切换，其中，UE和AMF是否支持5G网络与EPS网络间的切换，可以由AMF在UE从空闲态变为连接态时通过N2消息告知NG RAN；(3)EPS网络不支持语音业务，该条件可以由运营商作为本地策略配置在NG RAN上；(4)EPS网络的信号质量不满足语音业务需求，NG RAN可以通过指示UE去测量并上报周边EPS小区的信号质量确定EPS网络的信号质量是否满足语音业务需求。
B2、AMF根据接收到的N2会话响应向SMF+PGW-C发送携带有PDU会话修改命令的会话管理响应，其中向SMF+PGW-C透传第四SM信息。
B3、SMF+PGW-C确定保持向PCF+PCRF的通知，即暂缓向PCF+PCRF通知语音业务的用户面隧道的建立被拒绝的信息。
B4、NG RAN根据第一条件和第一SM信息向AMF发送切换请求。
B5、切换过程中，MME确定UE完成联合注册。
B6、MME通过SGW向SMF+PGW-C发送QCI＝5的用户面隧道的隧道修改请求，用于向SMF+PGW-C指示下行的SGW用户面地址和隧道信息。
B7、SMF+PGW-C向UPF+PGW-U发送隧道修改请求，向UPF+PGW-U指示QCI＝5专有承载的下行的SGW用户面地址和隧道信息。此后SMF+PGW-C通过SGW向MME反馈隧道修改响应。
B8、SMF+PGW-C向PCF+PCRF发送IP CAN会话修改消息。
IP CAN会话修改消息携带用于指示IMS语音业务的用户面隧道建立失败的信息，该指示信息可以为无线资源不足的指示信息(或资源分配失败的指示信息)。本实施例中，不限定该消息名称为IP-CAN会话修改消息，可以是其他消息名称，如CCR等。
B9、PCF+PCRF向P-CSCF发送RAR，RAR携带用于指示IMS语音业务的用户面隧道建立失败的信息。
B10、P-CSCF根据接收到的用于指示用户面隧道建立失败的信息确定无法在PS域建立IMS语音业务。
B11、P-CSCF向UE发送500响应消息。
步骤B11之后，UE发起CSFB主叫语音业务，UE侧和网络侧配合执行CSFB流程，最终可能在CS域建立语音呼叫。
在过程2中，由于P-CSCF在确定IMS语音业务的用户面隧道建立失败后才会向UE发送500响应消息，通过使得MME在确定UE完成联合注册之后，PCF+PCRF向P-CSCF发送用于指示IMS语音业务的用户面隧道建立失败的信息，从而使得IMS网络发送的500响应消息在UE完成EPS和CS域的联合注册流程之后才到达UE，为UE成功发起CSFB呼叫提供了保证。
过程3：
C1、NG RAN根据第一条件向AMF发送N2会话响应，N2会话响应携带第四SM信息，第四SM信息包括IMS语音业务的用户面隧道的建立被拒绝的信息，IMS语音业务的用户面隧道的建立被拒绝的信息包括无线资源不足(或资源分配失败)。
具体的，NG RAN可以根据第一条件确定第四SM信息。
该情况下，第一条件可以包括以下条件：(1)5G网络无法进行IMS语音业务，该条件表示5G网络并未部署IMS语音业务，或者当前5G网络信号覆盖差不足以满足IMS语音业务的要求；(2)5G网络的网络设备(AMF、NG RAN等)和UE支持5G网络与EPS网络间的切换，其中，UE和AMF是否支持5G网络与EPS网络间的切换，可以由AMF在UE从空闲态变为连接态时通过N2消息告知NG RAN；(3)EPS网络不支持语音业务，该条件可以由运营商作为本地策略配置在NG RAN上；(4)EPS网络的信号质量不满足语音业务需求，NG RAN可以通过指示UE去测量并上报周边EPS小区的信号质量确定EPS网络的信号质量是否满足语音业务需求。
C2、AMF根据接收到的N2会话响应向SMF+PGW-C发送携带有PDU会话修改命令的会话管理响应，其中向SMF+PGW-C透传第四SM信息。
C3、SMF+PGW-C根据接收到的AMF发送的携带有PDU会话修改命令的会话管理响应向UPF+PGW-U发送N4会话修改请求。
N4会话修改请求中包括第一命令，第一命令用于指示UPF+PGW-U缓存5QI＝5的用户面隧道上的数据。
C4、UPF+PGW-U根据接收到的N4会话修改请求向SMF+PGW-C反馈N4会话修改响应。
C5、SMF+PGW-C向PCF+PCRF发送PDU CAN会话修改消息。
PDU CAN会话修改消息携带用于指示IMS语音业务的用户面隧道建立失败的信息，该指示 信息可以为无线资源不足的指示信息(或资源分配失败的指示信息)。本实施例中，不限定该消息名称为IP-CAN会话修改消息，可以是其他消息名称，如CCR等。
C6、PCF+PCRF向P-CSCF发送RAR，RAR携带用于指示IMS语音业务的用户面隧道建立失败的信息。
C7、P-CSCF向PCF+PCRF反馈RAA。
C8、P-CSCF根据接收到的用于指示用户面隧道建立失败的信息确定无法在PS域建立IMS语音业务。
C9、P-CSCF向UE发送500响应消息，该消息到达UPF+PGW-U。
C10、UPF+PGW-U缓存5QI＝5的用户面隧道上的数据。
5QI＝5的用户面隧道上的数据可以包括500响应消息。
C11、NG RAN根据第一条件和第一SM信息向AMF发送切换请求。
C12、MME确定UE完成联合注册。
C13、MME通过SGW向SMF+PGW-C发送QCI＝5的用户面隧道的隧道修改请求(modify bearer request)，用于向SMF+PGW-C指示下行的SGW用户面地址和隧道信息。
C14、SMF+PGW-C向UPF+PGW-U发送隧道修改请求，该隧道修改请求包括第二命令，第二命令用于指示UPF+PGW-U停止缓存QCI＝1上的数据的信息。
在步骤C14之后，UPF+PGW-U会将500响应消息向UE发送，UE发起CSFB主叫语音业务，UE侧和网络侧配合执行CSFB流程，最终可能在CS域建立语音呼叫。
在过程3中，通过第一命令从而使得P-CSCF发送的500响应消息被缓存在UPF+PGW-U，在MME确定UE完成联合注册之后，通过第二命令使得P-CSCF将500响应消息向终端设备发送，从而使得IMS网络发送的500响应消息在UE完成EPS和CS域的联合注册流程之后才到达UE，为UE成功发起CSFB呼叫提供了保证。
过程4：
D1、NG RAN根据第一条件向AMF发送N2会话响应，N2会话响应携带第四SM信息，第四SM信息包括IMS语音业务的用户面隧道的建立被拒绝的信息，IMS语音业务的用户面隧道的建立被拒绝的信息包括无线资源不足(或资源分配失败)。
具体的，NG RAN可以根据第一条件确定第四SM信息。
该情况下，第一条件可以包括以下条件：(1)5G网络无法进行IMS语音业务，该条件表示5G网络并未部署IMS语音业务，或者当前5G网络信号覆盖差不足以满足IMS语音业务的要求；(2)5G网络的网络设备(AMF、NG RAN等)和UE支持5G网络与EPS网络间的切换，其中，UE和AMF是否支持5G网络与EPS网络间的切换，可以由AMF在UE从空闲态变为连接态时通过N2消息告知NG RAN。(3)EPS网络不支持语音业务，该条件可以由运营商作为本地策略配置在NG RAN上；(4)EPS网络的信号质量不满足语音业务需求，NG RAN可以通过指示UE去测量并上报周边EPS小区的信号质量确定EPS网络的信号质量是否满足语音业务需求。
D2、AMF根据接收到的N2会话响应向SMF+PGW-C发送携带有PDU会话修改命令的会话管理响应，其中向SMF+PGW-C透传第四SM信息。
D3、SMF+PGW-C向PCF+PCRF发送PDU CAN会话修改消息。本实施例中，不限定该消息名称为IP-CAN会话修改消息，可以是其他消息名称，如CCR等。
PDU CAN会话修改消息携带用于指示IMS语音业务的用户面隧道建立失败的信息，该指示信息可以为无线资源不足的指示信息(或资源分配失败的指示信息)。
D4、PCF+PCRF向P-CSCF发送RAR，RAR携带用于指示IMS语音业务的用户面隧道建立失败的信息。
D5、P-CSCF根据接收到的用于指示用户面隧道建立失败的信息确定无法在PS域建立IMS语音业务。
D6、P-CSCF向PCF+PCRF反馈RAA消息。
D7、P-CSCF确定延迟第二预设时间段发送500响应消息。
D8、NG RAN根据接收到的第一SM信息和第一条件向AMF发送切换请求以触发UE从5G网络切换至EPS网络。
在步骤D8之后，UE执行切换流程，待切换流程结束后，P-CSCF向UE发送500响应消息，UE发起CSFB主叫语音业务，UE侧和网络侧配合执行CSFB流程，最终可能在CS域建立语音呼叫。
在过程4中，P-CSCF延迟第二预设时间段发送500响应消息，从而使得IMS网络发送的500响应消息在UE完成EPS和CS域的联合注册流程之后才到达UE，为UE成功发起CSFB呼叫提供了保证。
该实施例还提供了一种被叫UE进行网络切换的方法，由于该实施例应用的场景为5G网络无法进行IMS语音业务并且EPS网络也无法进行IMS语音业务的场景，因此，为了保证UE成功发起CSFB呼叫，IMS网络发送的500响应消息需要在UE完成EPS和CS域的联合注册流程之后才到达TAS，以便于TAS将UE重新被叫域选至CS域，保证CSFB呼叫成功。参见图28，该方法包括：
2801-2808。
步骤2801-2808与步骤1901-1908分别对应相同。
2809-2814。
步骤2809-2814与步骤D1-D6分别对应相同。
2815、P-CSCF延迟第二预设时间段向TAS发送500响应消息。其中，500响应消息具体是发送给TAS中的被叫域选功能模块T-ADS。
P-CSCF延迟第二预设时间段发送500响应消息，从而使得P-CSCF发送的500响应消息在UE完成EPS和CS域的联合注册流程之后才到达TAS，为CSFB呼叫成功提供了保证。
实施例(3)和实施例(4)提供的网络切换方法，能够在IMS语音会话建立阶段，就使得5G终端设备切换至EPS网络，再在EPS网络利用CSFB技术使UE回落至2G/3G网络，最终在2G/3G网络CS域发起语音呼叫。本申请利用EPS网络作为跳板，重用传统的2G/3G网络架构，为处于5G网络的终端设备提供了一种在5G网络和EPS网络都无法进行IMS语音业务的场景下进行语音业务的方法。
上述实施例(1)至实施例(4)中的500响应消息，还可以为380响应消息或503响应消息，RAR消息还可以为会话中止请求(abort-session-request，简称ASR)消息，该情况下，RAA消息可以为会话中止应答(abort-session-answer，简称ASA)消息。
本申请实施例还提供了一种网络注册方法，如图28A所示，该方法包括：
2801A、第一移动性管理网元从终端设备接收注册请求(registration request)，注册请求用于请求将终端设备注册于第一网络。
其中，第一移动性管理网元可以为AMF，第一网络可以为5G网络。
2802A、若第三条件成立，第一移动性管理网元向终端设备发送第一指示信息，第一指示信息用于指示PS域的语音业务被支持。
其中，第三条件可以包括：第一网络支持将终端设备移动至第二网络。第一网络支持将终端设备移动至第二网络可以指第一网络支持通过切换或重定向或其他方式将终端设备移动至第二网络。
可选的，第一网络支持将终端设备移动至第二网络，可以包括：第一网络中的第一接入网设备支持在接收到来自会话管理网元的第一会话管理信息时，将终端设备接入第二网络，第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道。其中，第一接入网设备可以为NG RAN，会话管理网元可以为SMF+PGW-C功能网元。
示例性的，第一指示信息可以携带在注册接受消息中，语音业务可以为IMS语音业务，终端设备具体可以是发起主叫或被叫语音业务的终端设备。
具体地，第一移动性管理网元可以通过以下方式中的任意一种方式或其他方式确定第三条件是否成立：
(1)在终端设备注册于第一网络的过程中，第一移动性管理网元通过获取当前终端设备所在的接入网设备和/或核心网网元设备是否具备将终端设备移动至第二网络的能力来确定第三条件是否成立。
(2)第一移动性管理网元通过自身的配置条件来确定第三条件是否成立，该配置条件中配置了终端设备所在的接入网设备和/或核心网网元设备是否能够将终端设备移动至第二网络。
可选的，第一网络和第二网络的核心网相同，接入制式不同；或者，第一网络和第二网络的核心网和接入制式均不同。
在第一网络和第二网络的核心网和接入制式均不同的情况下，第二网络可以为EPS网络，在第一网络和第二网络的核心网相同，接入制式不同的情况下，第一网络和第二网络可以均为5G网络，区别在于第一网络和第二网络的接入制式不同。
具体的，第一接入网设备可以通过向第一移动性管理网元发送将终端设备从第一网络切换至第二网络的切换请求将终端设备接入第二网络。需要说明的是，当终端设备发起PS域语音业务时，第一接入网设备才将终端设备接入第二网络，终端设备可以是发起主叫PS域语音业务的终端设备，也可以是发起被叫PS域语音业务的终端设备。
可选的，第三条件还可以包括：第一网络与第二网络之间支持切换互操作。该情况下，第一网络支持通过切换将终端设备移动至第二网络。
可选的，第一网络与第二网络之间支持切换互操作，包括：第一网络和第二网络之间存在切换互操作接口。示例性的，切换互操作接口具体可以为N26接口。
可选地，第二网络可以支持PS域语音业务，也可以不支持PS域语音业务。若限定第二网络支持PS域语音业务，则第三条件还可以包括：第二网络能够能支持PS域语音业务。
可选的，在步骤2803A之前，该方法还可以包括：第一移动性管理网元确定终端设备为以语音业务为主的终端设备。由于以数据业务为主的终端设备与语音业务无关，该可选的方法可以区分终端类型，对于以数据业务为主的终端设备并不需要执行这套方案，即不需要确定第三条件是否成立，也不需要发送第一指示信息。
可选的，该方法还可以包括：终端设备生成注册请求，注册请求中携带终端设备为以语音业务为主的终端设备的指示信息；终端设备向第一移动性管理网元发送注册请求；该情况下，第一移动性管理网元确定终端设备为以语音业务为主的终端设备，包括：第一移动性管理网元根据注册请求确定终端设备为以语音业务为主的终端设备。
该情况下，终端设备通过注册请求携带终端设备为以语音业务为主的终端设备的指示信息，从而不用单独发送信令告知第一移动性管理网元该指示信息，能够节约信令开销。
可选的，在步骤2803A之前，该方法还可以包括：第一移动性管理网元确定终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程。由于只有终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的情况下，上述方法才可以实施，因此，可以提前确定该信息，避免影响无法支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的终端设备。
可选的，注册请求中还携带终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的指示信息，第一移动性管理网元确定终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程，包括：第一移动性管理网元根据注册请求确定终端设备支持在语音业务发起过程中从第一网络移动至第 二网络并通过第二网络继续语音业务的发起过程。
该情况下，终端设备通过注册请求携带终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的指示信息，从而不用单独发送信令告知第一移动性管理网元该指示信息，能够节约信令开销。
需要说明的是，该实施例提供的方法，可以执行在图28之前所述的任意一种方法之前。另外，第一移动性管理网元也可能不在第三条件下而在其他条件下向终端设备发送第一指示信息。
该实施例提供的方法，无论第一网络是否支持终端设备的语音业务，只要第一网络具备在终端设备发起语音业务时通过切换或其他方式将该终端设备回落至能提供语音业务的网络的能力，则在该终端设备向第一网络注册时，第一移动性管理网元便指示终端设备PS域的语音业务被支持，从而保证终端设备注册并驻留在第一网络而不重选至其他网络，节约网络资源，并且保证终端设备通过第一网络正常执行PS域语音业务注册流程和发起PS域语音呼叫流程。
本申请实施例还提供了一种网络注册方法，如图28B所示，用于对图28A所示的方法作具体说明，该方法包括：
2801B、UE向AMF发送注册请求。
具体的，注册请求用于请求将UE注册于第一网络，UE可以向NG RAN发送注册请求，NG RAN向AMF转发该注册请求。
注册请求中可以携带UE为以语音业务为主的UE的指示信息和UE支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的指示信息。
2802B、AMF从UE接收注册请求。
2803B、AMF根据注册请求确定UE支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程。
2804B、AMF根据注册请求确定UE为以语音业务为主的UE。
步骤2803B和步骤2804B的执行顺序不分先后。
2805B、AMF确定第三条件是否成立。
若是，执行步骤2806B。其中，第三条件包括：第一网络支持将UE移动至第二网络，第二网络能够支持PS域的语音业务。图28B中以AMF确定第三条件成立为例进行绘制。
2806B、AMF向UE发送第一指示信息，第一指示信息用于指示PS域的语音业务被支持。
其中，第一指示信息可以携带在注册接受消息中。
在步骤2806B之后，UE继续后续流程。
上述主要从各个网元之间交互的角度对本申请实施例提供的方案进行了介绍。可以理解的是，上述各个网络设备为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本申请实施例可以根据上述方法示例对各个网络设备进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。需要说明的是，本申请实施例中对模块的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
示例性的，下面示例性的给出了本申请实施例提供的网络设备的一种功能模块划分方式。
本申请实施例还提供了一种网络设备290，参见图29，包括处理单元2901和收发单元2902。
该网络设备可以为第一接入网设备、会话管理网元、第二移动性管理网元、第二接入网设备、IMS网元或第一移动性管理网元。
具体的，当图29所示的为第一接入网设备的示意图时，处理单元2901用于通过收发单元2902接收来自会话管理网元的第一会话管理信息，第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道；通过收发单元2902根据第一会话管理信息和第一条件向第一移动性管理网元发送切换请求，切换请求用于将终端设备从第一网络切换至第二网络，第一条件包括：第一网络无法进行语音业务。
可选的，第一条件还包括：第二网络支持语音业务、第二网络的信号质量满足语音业务需求和第一网络的网络设备以及终端设备支持第一网络与第二网络间的切换中的至少一个。
可选的，处理单元2901还用于通过收发单元2902向会话管理网元发送第二会话管理信息，第二会话管理信息包括语音业务的用户面隧道的建立被接受的信息。
可选的，处理单元2901还用于根据第一会话管理信息和第一条件确定不为语音业务的用户面隧道分配无线资源。
可选的，处理单元2901还用于通过收发单元2902向会话管理网元发送第三会话管理信息，第三会话管理信息包括语音业务的用户面隧道的建立被拒绝的信息。
可选的，语音业务的用户面隧道的建立被拒绝的信息包括拒绝的原因信息。
可选的，原因信息为终端设备在执行切换流程。
可选的，第一条件还包括：第二网络无法进行语音业务，处理单元2901还用于通过收发单元2902向会话管理网元发送第四会话管理信息，第四会话管理信息包括语音业务的用户面隧道的建立被拒绝的信息，语音业务的用户面隧道的建立被拒绝的信息包括无线资源不足。
当第一网络中的终端设备进行语音业务时，网络设备290可以通过将终端设备切换至第二网络，从而使得终端设备可以在第二网络进行语音业务，解决了第一网络中的终端设备无法进行语音业务的问题。
当图29所示的为会话管理网元的示意图时，处理单元2901用于通过收发单元2902接收第一接入网设备发送的第三会话管理信息，所述第三会话管理信息包括终端设备的语音业务的用户面隧道的建立被拒绝的原因信息；确定所述终端设备从第一网络切换至第二网络；根据所述原因信息在所述第二网络为所述语音业务建立用户面隧道。
可选的，所述原因信息为所述终端设备在执行切换流程。
可选的，处理单元2901具体用于根据所述原因信息和第二条件在第一预设时间段后在所述第二网络为所述语音业务建立用户面隧道，所述第二条件包括所述第二网络无法进行所述语音业务。
可选的，处理单元2901具体用于通过收发单元2902根据所述原因信息和所述第二条件在所述第一预设时间段后向所述第二网络的服务网关发送隧道建立请求，所述隧道建立请求用于请求建立所述语音业务的用户面隧道。
可选的，处理单元2901具体用于通过收发单元2902根据所述原因信息向所述第二网络的服务网关发送隧道建立请求，所述隧道建立请求用于请求建立语音业务用户面隧道；通过收发单元2902接收所述服务网关发送的隧道建立响应，所述隧道建立响应中包括所述语音业务的用户面隧道建立被拒绝的信息；通过收发单元2902根据所述第二条件在所述第一预设时间段后向策略功能控制网元发送第一消息，所述第一消息用于指示所述语音业务的用户面隧道建立失败。
当第一网络中的终端设备从第一网络切换至第二网络，网络设备290根据原因信息在第二网络为语音业务建立用户面隧道，若第二网络可以进行语音业务，则用户面隧道可以建立成功，从而使得终端设备可以在第二网络中进行语音业务，解决了第一网络中的终端设备无法进行语音业务的问题。
当图29所示的为第二移动性管理网元的示意图时，网络设备290可以执行以下动作一、动作二、动作三或动作四。
动作一、处理单元2901用于通过收发单元2902接收服务网关发送的隧道建立请求，所述隧道建立请求用于请求为终端设备建立语音业务的用户面隧道；通过收发单元2902根据第二条件向 所述服务网关发送隧道建立响应，所述隧道建立响应包括所述终端设备的语音业务的用户面隧道建立被拒绝的信息，所述第二条件包括第二网络无法进行所述语音业务。
可选的，所述第二条件还包括：所述终端设备为从第一网络切换至所述第二网络的终端设备。
可选的，处理单元2901还用于确定所述终端设备完成了联合注册。
处理单元2901具体用于确定接收到来自所述终端设备的联合注册完成消息。
网络设备290在第二网络无法进行语音业务时向服务网关发送隧道建立响应，以使得服务网关将用户面隧道建立被拒绝的信息传递至IMS网络，从而使得IMS网络触发终端设备的CSFB业务，进而使得终端设备进行CS语音业务。
动作二、处理单元2901用于通过收发单元2902向第二接入网设备发送无线隧道建立请求，所述无线隧道建立请求用于请求为终端设备的语音业务建立用户面隧道；通过收发单元2902接收所述第二接入网设备发送的无线隧道建立响应，所述无线隧道建立响应包括所述终端设备的语音业务的用户面隧道建立被拒绝的信息；通过收发单元2902根据第二条件向服务网关发送隧道建立响应，所述隧道建立响应包括所述终端设备的语音业务的用户面隧道建立被拒绝的信息，所述第二条件包括第二网络无法进行所述语音业务。
可选的，所述第二条件还包括：所述终端设备为从第一网络切换至所述第二网络的终端设备。
可选的，处理单元2901具体用于确定所述第二条件成立且所述终端设备完成联合注册；通过收发单元2902向所述服务网关发送隧道建立响应。
可选的，处理单元2901具体用于确定接收到来自所述终端设备的注册完成消息。
网络设备290将用户面隧道建立被拒绝的信息向服务网关发送，以使得服务网关将用户面隧道建立被拒绝的信息传递至IMS网络，从而使得IMS网络触发终端设备的CSFB业务，进而使得终端设备进行CS语音业务。
动作三、处理单元2901用于通过收发单元2902接收服务网关发送的隧道建立请求，所述隧道建立请求用于请求为用户设备终端设备建立语音业务的用户面隧道；若第二条件成立，确定所述终端设备完成联合注册，所述第二条件包括第二网络无法进行所述语音业务；通过收发单元2902向第二接入网设备发送无线隧道建立请求，所述无线隧道建立请求用于请求为所述终端设备的语音业务建立用户面隧道；通过收发单元2902接收所述第二接入网设备发送的无线隧道建立响应，所述无线隧道建立响应包括所述终端设备的语音业务的用户面隧道建立被拒绝的信息；通过收发单元2902根据所述无线隧道建立响应向所述服务网关发送隧道建立响应，所述隧道建立响应包括所述终端设备的语音业务的用户面隧道建立被拒绝的信息。
可选的，所述第二条件还包括：所述终端设备为从第一网络切换至所述第二网络的终端设备。
可选的，处理单元2901具体用于确定接收到所述终端设备发送的注册完成消息。
网络设备290确定终端设备完成联合注册后将用户面隧道建立被拒绝的信息向服务网关发送，以使得服务网关将用户面隧道建立被拒绝的信息传递至IMS网络，从而使得IMS网络触发终端设备的CSFB业务，进而使得终端设备进行CS语音业务，还可以保证终端设备成功发起CSFB呼叫。
动作四、处理单元2901用于通过收发单元2902接收第一移动性管理网元发送的第四消息，所述第四消息用于确认终端设备完成重定位；通过收发单元2902根据第二条件向服务网关发送隧道修改请求，所述隧道修改请求用于修改所述终端设备的语音业务的信令面隧道信息，所述第二条件包括第二网络无法进行所述语音业务。
可选的，处理单元2901具体用于确定所述第二条件成立且所述UE完成联合注册；通过收发单元2902向所述服务网关发送所述隧道修改请求。
在第二网络无法进行语音业务时，网络设备290向服务网关发送隧道修改请求，服务网关会将隧道修改请求转发至会话管理网元，由于会话管理网元是在接收到隧道修改请求后，才会向终端设备发送用于触发终端设备发起CSFB呼叫的消息(即上文中的第二消息)，因此，网络设备290可以在第二网络无法进行语音业务时触发终端设备发起CSFB呼叫，进而使得终端设备进行 CS语音业务。
当图29所示的为第二接入网设备的示意图时，处理单元2901用于通过收发单元2902接收第二移动性管理网元发送的无线隧道建立请求，所述无线隧道建立请求用于请求所述第二接入网设备为终端设备建立语音业务的用户面隧道；通过收发单元2902根据第二条件向所述第二移动性管理网元发送无线隧道建立响应，所述无线隧道建立响应包括所述语音业务的用户面隧道建立被拒绝的信息，所述第二条件包括第二网络无法进行所述语音业务。
可选的，所述第二条件还包括：所述终端设备为从第一网络切换至所述第二网络的终端设备。
网络设备290在第二网络无法进行语音业务时拒绝为用户面隧道分配无线资源，并将语音业务的用户面隧道建立被拒绝的信息携带在无线隧道建立响应中向第二移动性管理网元发送，第二移动性管理网元可以将用户面隧道建立被拒绝的信息传递给IMS网络，从而使得IMS网络触发终端设备的CSFB业务，进而使得终端设备进行CS语音业务。
当图29所示的为IMS网元的示意图时，处理单元2901用于通过收发单元2902接收为终端设备在分组交换PS域建立语音业务的请求消息；确定无法在第一网络或第二网络的PS域建立所述语音业务；确定所述终端设备完成联合注册；触发所述终端设备的电路域交换回落CSFB业务。
可选的，处理单元2901还用于确定所述终端设备注册于所述第一网络。
可选的，处理单元2901具体用于获取来自所述第一网络PS域的所述语音业务建立失败信息；或，获取来自所述第二网络PS域的所述语音业务建立失败信息。
可选的，处理单元2901具体用于确定无法在所述第一网络或所述第二网络的PS域建立所述语音业务起的第二预设时间段后，确定所述终端设备完成联合注册；或者，根据从策略控制网元或归属用户服务器获得的所述终端设备的注册位置信息，确定所述终端设备完成联合注册。
可选的，所述终端设备为所述语音业务的主叫终端设备，处理单元2901具体用于通过收发单元2902向所述主叫终端设备发送第二消息，所述第二消息用于触发所述主叫终端设备发起CSFB主叫业务。
可选的，所述终端设备为所述语音业务的被叫终端设备，处理单元2901具体用于通过收发单元2902向被叫域选设备发送第三消息，所述第三消息用于指示在所述第一网络或所述第二网络的PS域的被叫语音业务建立失败，以使所述被叫域选设备触发所述被叫终端设备的CSFB被叫语音业务。
网络设备290在确定无法在第一网络或第二网络的PS域建立语音业务、并且终端设备完成联合注册时，触发终端设备的CSFB业务，由于终端设备完成联合注册是终端设备发起CSFB呼叫的必要条件，因此，可以保证终端设备成功发起CSFB呼叫，进而使得终端设备进行CS语音业务。
当图29所示的为第一移动性管理网元的示意图时，处理单元2901用于通过收发单元2902从终端设备接收注册请求，注册请求用于请求将终端设备注册于第一网络；处理单元2901还用于确定第三条件成立，第三条件包括：第一网络支持将终端设备移动至第二网络，第二网络能够支持PS域的语音业务；处理单元2901还用于通过收发单元2902向终端设备发送第一指示信息，第一指示信息用于指示PS域的语音业务被支持。
可选的，第一网络和第二网络的核心网相同，接入制式不同；或者，第一网络和第二网络的核心网和接入制式均不同。
可选的，第一网络支持将终端设备移动至第二网络，包括：第一网络中的第一接入网设备支持在接收到来自会话管理网元的第一会话管理信息时，将终端设备接入第二网络，第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道。
可选的，第三条件还包括：第一网络与第二网络之间支持切换互操作。
可选的，第一网络与第二网络之间支持切换互操作，包括：第一网络和第二网络之间存在切换互操作接口。
可选的，处理单元2901还用于确定终端设备为以语音业务为主的终端设备。
可选的，注册请求中携带终端设备为以语音业务为主的终端设备的指示信息，处理单元2901具体用于根据注册请求确定终端设备为以语音业务为主的终端设备。
可选的，处理单元2901还用于确定终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程。
可选的，注册请求中还携带终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的指示信息，处理单元2901具体用于根据注册请求确定终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程。
无论第一网络是否支持终端设备的语音业务，只要第一网络具备在终端设备发起语音业务时通过切换或其他方式将该终端设备回落至能提供语音业务的网络的能力，则在该终端设备向第一网络注册时，第一移动性管理网元便指示终端设备PS域的语音业务被支持，从而保证终端设备注册并驻留在第一网络而不重选至其他网络，节约网络资源，并且保证终端设备通过第一网络正常执行PS域语音业务注册流程和发起PS域语音呼叫流程。
本申请实施例还提供了一种终端设备290A，参见图29A，包括处理单元2901A和收发单元2902A。处理单元2901A用于生成注册请求，注册请求用于请求将终端设备注册于第一网络，注册请求中携带终端设备为以语音业务为主的终端设备的指示信息；处理单元2901A还用于通过收发单元2902A向第一移动性管理网元发送注册请求。
可选的，注册请求中还包括终端设备支持在语音业务发起过程中从第一网络移动至第二网络并通过第二网络继续语音业务的发起过程的指示信息。
可选的，第一网络和第二网络的核心网相同，接入制式不同；或者，第一网络和第二网络的核心网和接入制式均不同。
在第一网络具备在终端设备发起语音业务时通过切换或其他方式将该终端设备回落至能提供语音业务的网络的能力时，终端设备根据接收到的第一移动性管理网元发送的第一指示信息，注册并驻留在第一网络而不重选至其他网络，节约网络资源，并且保证终端设备通过第一网络正常执行PS域语音业务注册流程和发起PS域语音呼叫流程。
本申请实施例还提供了一种网络设备，包括：存储器、处理器和通信接口；存储器用于存储计算机执行指令，处理器执行存储器存储的计算机执行指令，并通过通信接口使得网络设备实现指令对应的方法。网络设备的结构示意图可以参见图6。
该网络设备可以为第一接入网设备、会话管理网元、第二移动性管理网元、第二接入网设备、IMS网元或第一移动性管理网元。具体的，当图6和图29所示的为第一接入网设备的示意图时，处理单元2901可以为处理器601，收发单元2902可以为通信接口604；当图6和图29所示的为会话管理网元的示意图时，处理单元2901可以为处理器601，收发单元2902可以为通信接口604；当图6和图29所示的为第二移动性管理网元的示意图时，处理单元2901可以为处理器601，收发单元2902可以为通信接口604；当图6和图29所示的为第二接入网设备的示意图时，处理单元2901可以为处理器601，收发单元2902可以为通信接口604；当图6和图29所示的为IMS网元的示意图时，处理单元2901可以为处理器601，收发单元2902可以为通信接口604；当图6和图29所示的为第一移动性管理网元的示意图时，处理单元2901可以为处理器601，收发单元2902可以为通信接口604。
本申请实施例还提供了一种终端设备，包括：存储器、处理器和通信接口；存储器用于存储计算机执行指令，处理器执行存储器存储的计算机执行指令，并通过通信接口使得终端设备实现指令对应的方法。终端设备的结构示意图可以参见图6A。处理单元2901A可以为处理器601A，收发单元2902A可以为通信接口604A。
本申请实施例还提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行上述方法。
本申请实施例还提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述方法。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件程序实现时，可以全部或部分地以计算机程序产品的形式来实现。该计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或者数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，简称DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可以用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)，光介质(例如，DVD)、或者半导体介质(例如固态硬盘(solid state disk，简称SSD))等。
尽管在此结合各实施例对本申请进行了描述，然而，在实施所要求保护的本申请过程中，本领域技术人员通过查看所述附图、公开内容、以及所附权利要求书，可理解并实现所述公开实施例的其他变化。在权利要求中，“包括”(comprising)一词不排除其他组成部分或步骤，“一”或“一个”不排除多个的情况。单个处理器或其他单元可以实现权利要求中列举的若干项功能。相互不同的从属权利要求中记载了某些措施，但这并不表示这些措施不能组合起来产生良好的效果。
尽管结合具体特征及其实施例对本申请进行了描述，显而易见的，在不脱离本申请的精神和范围的情况下，可对其进行各种修改和组合。相应地，本说明书和附图仅仅是所附权利要求所界定的本申请的示例性说明，且视为已覆盖本申请范围内的任意和所有修改、变化、组合或等同物。显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的精神和范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (56)

  1. 一种网络切换方法，其特征在于，包括：
    第一接入网设备接收来自会话管理网元的第一会话管理信息，所述第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道；
    所述第一接入网设备根据所述第一会话管理信息和第一条件向第一移动性管理网元发送切换请求，所述切换请求用于将所述终端设备从第一网络切换至第二网络，所述第一条件包括：所述第一网络无法进行所述语音业务。
  2. 根据权利要求1所述的网络切换方法，其特征在于，所述第一条件还包括：所述第二网络支持所述语音业务、所述第二网络的信号质量满足所述语音业务需求和所述第一网络的网络设备以及所述终端设备支持所述第一网络与所述第二网络间的切换中的至少一个。
  3. 根据权利要求1或2所述的网络切换方法，其特征在于，所述网络切换方法还包括：
    所述第一接入网设备向所述会话管理网元发送第二会话管理信息，所述第二会话管理信息包括所述语音业务的用户面隧道的建立被接受的信息。
  4. 根据权利要求3所述的网络切换方法，其特征在于，在所述第一接入网设备向所述会话管理网元发送第二会话管理信息之前，所述网络切换方法还包括：
    所述第一接入网设备根据所述第一会话管理信息和所述第一条件确定不为所述语音业务的用户面隧道分配无线资源。
  5. 根据权利要求1或2所述的网络切换方法，其特征在于，所述网络切换方法还包括：
    所述第一接入网设备向所述会话管理网元发送第三会话管理信息，所述第三会话管理信息包括所述语音业务的用户面隧道的建立被拒绝的信息。
  6. 根据权利要求5所述的网络切换方法，其特征在于，所述语音业务的用户面隧道的建立被拒绝的信息包括拒绝的原因信息。
  7. 根据权利要求6所述的网络切换方法，其特征在于，所述原因信息为：所述终端设备在执行切换流程。
  8. 根据权利要求1所述的网络切换方法，其特征在于，所述第一条件还包括：所述第二网络无法进行所述语音业务，所述网络切换方法还包括：
    所述第一接入网设备向所述会话管理网元发送第四会话管理信息，所述第四会话管理信息包括所述语音业务的用户面隧道的建立被拒绝的信息，所述语音业务的用户面隧道的建立被拒绝的信息包括无线资源不足。
  9. 一种网络设备，其特征在于，包括：处理单元和收发单元；
    所述处理单元用于：
    通过所述收发单元接收来自会话管理网元的第一会话管理信息，所述第一会话管理信息用于请求为终端设备的语音业务建立用户面隧道；
    通过所述收发单元根据所述第一会话管理信息和第一条件向第一移动性管理网元发送切换请求，所述切换请求用于将所述终端设备从第一网络切换至第二网络，所述第一条件包括：所述第一网络无法进行所述语音业务。
  10. 根据权利要求9所述的网络设备，其特征在于，所述第一条件还包括：所述第二网络支持所述语音业务、所述第二网络的信号质量满足所述语音业务需求和所述第一网络的网络设备以及所述终端设备支持所述第一网络与所述第二网络间的切换中的至少一个。
  11. 根据权利要求9或10所述的网络设备，其特征在于，
    所述处理单元还用于通过所述收发单元向所述会话管理网元发送第二会话管理信息，所述第二会话管理信息包括所述语音业务的用户面隧道的建立被接受的信息。
  12. 根据权利要求11所述的网络设备，其特征在于，
    所述处理单元，还用于根据所述第一会话管理信息和所述第一条件确定不为所述语音业务的 用户面隧道分配无线资源。
  13. 根据权利要求9或10所述的网络设备，其特征在于，
    所述处理单元还用于通过所述收发单元向所述会话管理网元发送第三会话管理信息，所述第三会话管理信息包括所述语音业务的用户面隧道的建立被拒绝的信息。
  14. 根据权利要求13所述的网络设备，其特征在于，所述语音业务的用户面隧道的建立被拒绝的信息包括拒绝的原因信息。
  15. 根据权利要求14所述的网络设备，其特征在于，所述原因信息为：所述终端设备在执行切换流程。
  16. 根据权利要求9所述的网络设备，其特征在于，所述第一条件还包括：所述第二网络无法进行所述语音业务，
    所述处理单元还用于通过所述收发单元向所述会话管理网元发送第四会话管理信息，所述第四会话管理信息包括所述语音业务的用户面隧道的建立被拒绝的信息，所述语音业务的用户面隧道的建立被拒绝的信息包括无线资源不足。
  17. 一种网络切换方法，包括：
    会话管理网元接收第一接入网设备发送的第三会话管理信息，所述第三会话管理信息包括终端设备的语音业务的用户面隧道的建立被拒绝的原因信息；
    所述会话管理网元确定所述终端设备从第一网络切换至第二网络；
    所述会话管理网元根据所述原因信息在所述第二网络为所述语音业务建立用户面隧道。
  18. 根据权利要求17所述的网络切换方法，其特征在于，所述原因信息为：所述终端设备在执行切换流程。
  19. 根据权利要求17或18所述的网络切换方法，其特征在于，所述会话管理网元根据所述原因信息在所述第二网络为所述语音业务建立用户面隧道，包括：
    所述会话管理网元根据所述原因信息和第二条件在第一预设时间段后在所述第二网络为所述语音业务建立用户面隧道，所述第二条件包括所述第二网络无法进行语音业务。
  20. 根据权利要求19所述的网络切换方法，其特征在于，所述会话管理网元根据所述原因信息和第二条件在第一预设时间段后在所述第二网络为所述语音业务建立用户面隧道，包括：
    所述会话管理网元根据所述原因信息和所述第二条件在所述第一预设时间段后向所述第二网络的服务网关发送隧道建立请求，所述隧道建立请求用于请求建立所述语音业务的用户面隧道。
  21. 根据权利要求19所述的网络切换方法，其特征在于，所述会话管理网元根据所述原因信息和第二条件在第一预设时间段后在所述第二网络为所述语音业务建立用户面隧道，包括：
    所述会话管理网元根据所述原因信息向所述第二网络的服务网关发送隧道建立请求，所述隧道建立请求用于请求建立所述语音业务的用户面隧道；
    所述会话管理网元接收所述服务网关发送的隧道建立响应，所述隧道建立响应中包括所述语音业务的用户面隧道建立被拒绝的信息；
    所述会话管理网元根据所述第二条件在所述第一预设时间段后向策略功能控制网元发送第一消息，所述第一消息用于指示所述语音业务的用户面隧道建立失败。
  22. 一种网络注册方法，包括：
    第一移动性管理网元从终端设备接收注册请求，所述注册请求用于请求将所述终端设备注册于第一网络；
    若第三条件成立，所述第一移动性管理网元向所述终端设备发送第一指示信息，所述第一指示信息用于指示分组交换PS域的语音业务被支持，所述第三条件包括：所述第一网络支持将所述终端设备移动至第二网络。
  23. 根据权利要求22所述的网络注册方法，其特征在于，所述第一网络支持将所述终端设备移动至第二网络包括：所述第一网络支持通过切换或重定向方式将所述终端设备移动至所述第二 网络。
  24. 根据权利要求22或23所述的网络注册方法，其特征在于，所述第一网络和所述第二网络的核心网相同，接入制式不同；或者，所述第一网络和所述第二网络的核心网和接入制式均不同。
  25. 根据权利要求24所述的网络注册方法，其特征在于，所述第一网络和所述第二网络的核心网相同，接入制式不同，包括：所述第一网络和所述第二网络的核心网为第五代5G核心网，所述第一网络的接入制式为下一代无线接入网NG RAN，所述第二网络的接入制式为演进型通用陆地无线接入网E-UTRAN。
  26. 根据权利要求24所述的网络注册方法，其特征在于，所述第一网络和所述第二网络的核心网和接入制式均不同，包括：所述第一网络的核心网为5G核心网，所述第二网络的核心网为第四代4G核心网，所述第一网络的接入制式为NG RAN，所述第二网络的接入制式为E-UTRAN。
  27. 根据权利要求22-26任一项所述的网络注册方法，其特征在于，所述第一网络支持将所述终端设备移动至第二网络，包括：所述第一网络中的第一接入网设备支持在接收到来自会话管理网元的第一会话管理信息时，将所述终端设备接入所述第二网络，所述第一会话管理信息用于请求为所述终端设备的语音业务建立用户面隧道。
  28. 根据权利要求22-27任一项所述的网络注册方法，其特征在于，所述第三条件还包括：所述第一网络与所述第二网络之间支持切换互操作，和，所述第二网络能够支持PS域的语音业务中的至少一个。
  29. 根据权利要求28所述的网络注册方法，其特征在于，所述第一网络与所述第二网络之间支持切换互操作，包括：所述第一网络和所述第二网络之间存在切换互操作接口。
  30. 根据权利要求22-29所述的网络注册方法，其特征在于，在所述第一移动性管理网元向所述终端设备发送第一指示信息之前，所述网络注册方法还包括：
    所述第一移动性管理网元确定所述终端设备为以语音业务为主的终端设备。
  31. 根据权利要求30所述的网络注册方法，其特征在于，所述注册请求中携带所述终端设备为以语音业务为主的终端设备的指示信息，所述第一移动性管理网元确定所述终端设备为以语音业务为主的终端设备，包括：
    所述第一移动性管理网元根据所述注册请求确定所述终端设备为以语音业务为主的终端设备。
  32. 根据权利要求22-29所述的网络注册方法，其特征在于，在所述第一移动性管理网元向所述终端设备发送第一指示信息之前，所述网络注册方法还包括：
    所述第一移动性管理网元确定所述终端设备支持在语音业务发起过程中从所述第一网络移动至所述第二网络并通过所述第二网络继续语音业务的发起过程。
  33. 根据权利要求32所述的网络注册方法，其特征在于，所述注册请求中还携带所述终端设备支持在语音业务发起过程中从所述第一网络移动至所述第二网络并通过所述第二网络继续所述语音业务的发起过程的指示信息，所述第一移动性管理网元确定所述终端设备支持在语音业务发起过程中从所述第一网络移动至所述第二网络并通过所述第二网络继续语音业务的发起过程，包括：
    所述第一移动性管理网元根据所述注册请求确定所述终端设备支持在语音业务发起过程中从所述第一网络移动至所述第二网络并通过所述第二网络继续语音业务的发起过程。
  34. 一种网络注册方法，包括：
    终端设备生成注册请求，所述注册请求用于请求将所述终端设备注册于第一网络，所述注册请求中携带所述终端设备为以语音业务为主的终端设备的指示信息；
    所述终端设备向所述第一移动性管理网元发送注册请求。
  35. 根据权利要求34所述的网络注册方法，其特征在于，所述注册请求中还包括所述终端设备支持在语音业务发起过程中从所述第一网络移动至第二网络并通过所述第二网络继续语音业务 的发起过程的指示信息。
  36. 根据权利要求35所述的网络注册方法，其特征在于，所述第一网络和所述第二网络的核心网相同，接入制式不同；或者，所述第一网络和所述第二网络的核心网和接入制式均不同。
  37. 一种网络设备，包括：收发单元和处理单元；
    所述收发单元，用于接收第一接入网设备发送的第三会话管理信息，所述第三会话管理信息包括终端设备的语音业务的用户面隧道的建立被拒绝的原因信息；
    所述处理单元，用于确定所述终端设备从第一网络切换至第二网络；
    所述处理单元，还用于根据所述原因信息在所述第二网络为所述语音业务建立用户面隧道。
  38. 根据权利要求37所述的网络设备，其特征在于，所述原因信息为：所述终端设备在执行切换流程。
  39. 根据权利要求37或38所述的网络设备，其特征在于，所述处理单元，具体用于：
    根据所述原因信息和第二条件在第一预设时间段后在所述第二网络为所述语音业务建立用户面隧道，所述第二条件包括所述第二网络无法进行语音业务。
  40. 根据权利要求39所述的网络设备，其特征在于，
    所述处理单元，具体用于根据所述原因信息和所述第二条件在所述第一预设时间段后，通过所述收发单元向所述第二网络的服务网关发送隧道建立请求，所述隧道建立请求用于请求建立所述语音业务的用户面隧道。
  41. 根据权利要求39所述的网络设备，其特征在于，
    所述处理单元，具体用于根据所述原因信息通过所述收发单元向所述第二网络的服务网关发送隧道建立请求，所述隧道建立请求用于请求建立所述语音业务的用户面隧道；
    所述处理单元，具体用于通过所述收发单元接收所述服务网关发送的隧道建立响应，所述隧道建立响应中包括所述语音业务的用户面隧道建立被拒绝的信息；
    所述处理单元，具体用于根据所述第二条件在所述第一预设时间段后通过所述收发单元向策略功能控制网元发送第一消息，所述第一消息用于指示所述语音业务的用户面隧道建立失败。
  42. 一种网络设备，包括：收发单元和处理单元；
    所述处理单元，用于通过所述收发单元从终端设备接收注册请求，所述注册请求用于请求将所述终端设备注册于第一网络；
    所述处理单元还用于确定第三条件成立；
    所述处理单元还用于通过所述收发单元向所述终端设备发送第一指示信息，所述第一指示信息用于指示分组交换PS域的语音业务被支持，所述第三条件包括：所述第一网络支持将所述终端设备移动至第二网络。
  43. 根据权利要求42所述的网络设备，其特征在于，所述第一网络支持将所述终端设备移动至第二网络包括：所述第一网络支持通过切换或重定向方式将所述终端设备移动至所述第二网络。
  44. 根据权利要求42或43所述的网络设备，其特征在于，所述第一网络和所述第二网络的核心网相同，接入制式不同；或者，所述第一网络和所述第二网络的核心网和接入制式均不同。
  45. 根据权利要求44所述的网络设备，其特征在于，所述第一网络和所述第二网络的核心网相同，接入制式不同，包括：所述第一网络和所述第二网络的核心网为第五代5G核心网，所述第一网络的接入制式为下一代无线接入网NG RAN，所述第二网络的接入制式为演进型通用陆地无线接入网E-UTRAN。
  46. 根据权利要求44所述的网络设备，其特征在于，所述第一网络和所述第二网络的核心网和接入制式均不同，包括：所述第一网络的核心网为5G核心网，所述第二网络的核心网为第四代4G核心网，所述第一网络的接入制式为NG RAN，所述第二网络的接入制式为E-UTRAN。
  47. 根据权利要求42-46任一项所述的网络设备，其特征在于，所述第一网络支持将所述终端设备移动至第二网络，包括：所述第一网络中的第一接入网设备支持在接收到来自会话管理网 元的第一会话管理信息时，将所述终端设备接入所述第二网络，所述第一会话管理信息用于请求为所述终端设备的语音业务建立用户面隧道。
  48. 根据权利要求42-47任一项所述的网络设备，其特征在于，所述第三条件还包括：所述第一网络与所述第二网络之间支持切换互操作，和，所述第二网络能够支持PS域的语音业务中的至少一个。
  49. 根据权利要求48所述的网络设备，其特征在于，所述第一网络与所述第二网络之间支持切换互操作，包括：所述第一网络和所述第二网络之间存在切换互操作接口。
  50. 根据权利要求42-49所述的网络设备，其特征在于，所述处理单元，还用于：
    确定所述终端设备为以语音业务为主的终端设备。
  51. 根据权利要求50所述的网络设备，其特征在于，所述注册请求中携带所述终端设备为以语音业务为主的终端设备的指示信息，所述处理单元，具体用于：
    根据所述注册请求确定所述终端设备为以语音业务为主的终端设备。
  52. 根据权利要求42-49所述的网络设备，其特征在于，
    所述处理单元，还用于确定所述终端设备支持在语音业务发起过程中从所述第一网络移动至所述第二网络并通过所述第二网络继续语音业务的发起过程。
  53. 根据权利要求52所述的网络设备，其特征在于，所述注册请求中还携带所述终端设备支持在语音业务发起过程中从所述第一网络移动至所述第二网络并通过所述第二网络继续所述语音业务的发起过程的指示信息，所述处理单元，具体用于：
    根据所述注册请求确定所述终端设备支持在语音业务发起过程中从所述第一网络移动至所述第二网络并通过所述第二网络继续语音业务的发起过程。
  54. 一种终端设备，包括：收发单元和处理单元；
    所述处理单元，用于生成注册请求，所述注册请求用于请求将所述终端设备注册于第一网络，所述注册请求中携带所述终端设备为以语音业务为主的终端设备的指示信息；
    所述收发单元，用于向第一移动性管理网元发送注册请求。
  55. 根据权利要求54所述的终端设备，其特征在于，所述注册请求中还包括所述终端设备支持在语音业务发起过程中从所述第一网络移动至第二网络并通过所述第二网络继续语音业务的发起过程的指示信息。
  56. 根据权利要求55所述的终端设备，其特征在于，所述第一网络和所述第二网络的核心网相同，接入制式不同；或者，所述第一网络和所述第二网络的核心网和接入制式均不同。
PCT/CN2018/091759 2017-07-14 2018-06-19 网络切换方法及装置 WO2019011107A1 (zh)

Priority Applications (13)

Application Number Priority Date Filing Date Title
MYPI2018002725A MY201248A (en) 2017-07-14 2018-06-19 Network registration method, network handover method, network device and terminal device
CN201880046927.5A CN110945903B (zh) 2017-07-14 2018-06-19 网络切换方法及装置
KR1020197002390A KR102198411B1 (ko) 2017-07-14 2018-06-19 네트워크 등록 방법, 네트워크 핸드오버 방법, 네트워크 디바이스 및 단말기 디바이스
JP2019500561A JP6724235B2 (ja) 2017-07-14 2018-06-19 ネットワーク登録方法、ネットワークハンドオーバ方法、ネットワーク装置および端末装置
EP18815923.0A EP3462776B1 (en) 2017-07-14 2018-06-19 Network switching method and apparatus
RU2019105002A RU2717839C1 (ru) 2017-07-14 2018-06-19 Способ регистрации в сети, способ передачи обслуживания в сети, сетевое устройство и оконечное устройство
AU2018298508A AU2018298508B2 (en) 2017-07-14 2018-06-19 Network registration method, network handover method, network device and terminal device
BR112019000557-9A BR112019000557A2 (pt) 2017-07-14 2018-06-19 método de registro de rede, método de mudança automática de rede, dispositivo de rede e dispositivo terminal
ES18815923T ES2862404T3 (es) 2017-07-14 2018-06-19 Método y aparato de conmutación de red
EP20203815.4A EP3833103B1 (en) 2017-07-14 2018-06-19 Network handover method and apparatus
US16/198,219 US10939345B2 (en) 2017-07-14 2018-11-21 Network handover method and network device
AU2020244393A AU2020244393B2 (en) 2017-07-14 2020-09-28 Network handover method, apparatus and system
US17/085,714 US11323933B2 (en) 2017-07-14 2020-10-30 Network handover method and network device

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CN201710577345 2017-07-14
CN201710577345.7 2017-07-14
CN201710693995.8 2017-08-14
CN201710693995.8A CN109257779A (zh) 2017-07-14 2017-08-14 网络切换方法及装置

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US16/198,219 Continuation US10939345B2 (en) 2017-07-14 2018-11-21 Network handover method and network device

Publications (1)

Publication Number Publication Date
WO2019011107A1 true WO2019011107A1 (zh) 2019-01-17

Family

ID=64620647

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2018/091759 WO2019011107A1 (zh) 2017-07-14 2018-06-19 网络切换方法及装置

Country Status (2)

Country Link
CN (3) CN109257780B (zh)
WO (1) WO2019011107A1 (zh)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020529167A (ja) * 2017-08-02 2020-10-01 中興通訊股▲ふん▼有限公司Ｚｔｅ Ｃｏｒｐｏｒａｔｉｏｎ ネットワークハンドオーバ方法、装置、およびシステム
EP3720236A1 (en) * 2019-04-05 2020-10-07 T-Mobile USA, Inc. Efficient evolved packet system (eps) fallback
CN111770587A (zh) * 2019-04-02 2020-10-13 华为技术有限公司 一种数据处理方法、装置及系统
CN112073512A (zh) * 2020-09-08 2020-12-11 中国联合网络通信集团有限公司 数据处理方法及设备
EP3768021A1 (en) * 2019-07-16 2021-01-20 T-Mobile USA, Inc. Timer-initiated fallback
WO2021013353A1 (en) * 2019-07-25 2021-01-28 Telefonaktiebolaget Lm Ericsson (Publ) Fallback during call set-up
CN113115318A (zh) * 2021-03-18 2021-07-13 中国联合网络通信集团有限公司 通信管制方法及装置
CN113709903A (zh) * 2020-05-21 2021-11-26 华为技术有限公司 一种通信方法、设备及系统
US11284463B2 (en) 2019-07-16 2022-03-22 T-Mobile Usa, Inc. Automatically resetting interrupted network connections
CN114449592A (zh) * 2020-10-30 2022-05-06 展讯半导体(成都)有限公司 通信方法、装置、设备及存储介质

Families Citing this family (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109257780B (zh) * 2017-07-14 2021-06-01 华为技术有限公司 网络切换方法及装置
CN109257779A (zh) 2017-07-14 2019-01-22 华为技术有限公司 网络切换方法及装置
CN110719613B (zh) 2018-07-12 2021-08-03 华为技术有限公司 一种建立语音业务的方法及装置
CN111436160B (zh) * 2019-01-15 2022-04-29 华为技术有限公司 一种局域网通信方法、装置及系统
CN111600916B (zh) * 2019-02-02 2022-03-25 华为技术有限公司 无人机控制方法、装置及系统
CN111586642B (zh) * 2019-02-19 2021-12-14 华为技术有限公司 一种通信方法及装置
CN111757391B (zh) 2019-03-29 2024-04-12 华为技术有限公司 一种通信方法及装置
CN113365238B (zh) * 2019-03-29 2022-03-29 华为技术有限公司 一种计费方法和装置
US11343699B2 (en) * 2019-04-09 2022-05-24 Mediatek Inc. EPS bearer context status synchronization upon inter-system change from evolved packet system (EPS) to fifth generation system (5GS)
US11259205B2 (en) * 2019-05-06 2022-02-22 Mediatek Inc. IP multimedia core network subsystem signaling in 5GS
WO2020223909A1 (zh) * 2019-05-07 2020-11-12 Oppo广东移动通信有限公司 一种上下文管理方法、设备及存储介质
KR20200131149A (ko) * 2019-05-13 2020-11-23 삼성전자주식회사 무선통신 시스템에서 서비스 유연하게 제공하는 방법 및 장치
CN113812176B (zh) * 2019-05-17 2023-03-31 华为技术有限公司 一种选网系统及终端设备
CN111988821B (zh) * 2019-05-22 2021-10-22 华为技术有限公司 语音通信方法及其装置
CN110351804B (zh) * 2019-06-17 2021-11-12 腾讯科技（深圳）有限公司 通信方法、装置、计算机可读介质及电子设备
CN112243279B (zh) * 2019-07-18 2022-03-29 华为技术有限公司 实现业务连续的方法、相关装置及系统
CN112312539B (zh) * 2019-07-30 2022-01-14 华为技术有限公司 策略控制功能网元的选择方法、装置、系统及存储介质
CN110809299B (zh) * 2019-11-07 2021-07-27 腾讯科技（深圳）有限公司 一种广播业务的模式切换方法以及相关装置
EP4047985A4 (en) * 2019-12-05 2022-11-09 Huawei Technologies Co., Ltd. METHOD, APPARATUS AND SYSTEM FOR INTERWORKING BETWEEN NETWORKS
CN114915614B (zh) * 2019-12-20 2023-04-11 华为技术有限公司 一种恢复ims业务的方法及装置
CN115361660B (zh) * 2020-01-07 2024-04-09 华为技术有限公司 用于语音业务的通信方法、装置和系统
CN111246530B (zh) 2020-02-06 2022-10-18 北京小米移动软件有限公司 网络切换方法及装置、存储介质
CN113630839B (zh) * 2020-05-07 2022-06-14 华为技术有限公司 一种被叫域选择方法和装置
CN113630822B (zh) * 2020-05-08 2023-05-02 华为技术有限公司 组播业务切换的方法和装置
CN115087052B (zh) * 2021-03-11 2023-11-14 北京小米移动软件有限公司 语音呼叫方法、装置、存储介质及电子设备
CN115442793A (zh) * 2021-06-02 2022-12-06 华为技术有限公司 一种呼叫处理方法及通信装置
CN117793064A (zh) * 2022-09-22 2024-03-29 维沃移动通信有限公司 通信方法、装置、ue及可读存储介质

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101453719A (zh) * 2007-12-07 2009-06-10 华为技术有限公司 实现互联网协议语音业务切换的方法、系统和设备
CN101472313A (zh) * 2007-12-27 2009-07-01 华为技术有限公司 一种语音业务切换方法、系统和装置
CN102461276A (zh) * 2009-06-03 2012-05-16 捷讯研究有限公司 演进分组系统中的语音服务
CN102984770A (zh) * 2012-12-04 2013-03-20 中国联合网络通信集团有限公司 网络切换方法、移动管理实体、基站和网络系统
WO2014036338A2 (en) * 2012-08-31 2014-03-06 Qualcomm Incorporated Selective network parameter configuratons based on network identification of non-ims multimedia applications

Family Cites Families (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101291453B (zh) * 2007-04-17 2012-08-08 华为技术有限公司 一种实现会话的语音连续性的方法及装置
CN101841836A (zh) * 2009-03-19 2010-09-22 华为技术有限公司 一种切换的优化方法、切换装置和系统
CN102378295B (zh) * 2010-08-23 2016-01-20 中兴通讯股份有限公司 承载释放方法及系统
CN102387557B (zh) * 2010-08-30 2014-09-17 华为技术有限公司 反向单一无线语音呼叫连续性的处理方法、设备及系统
CN104254111B (zh) * 2010-08-30 2018-08-14 华为技术有限公司 反向单一无线语音呼叫连续性的处理方法、设备及系统
EP2622904B1 (en) * 2010-09-28 2023-04-26 BlackBerry Limited Method and user equipment having at least one pdn connection comprising lipa connectivity
EP2638753B1 (en) * 2010-11-12 2014-08-06 Telefonaktiebolaget LM Ericsson (PUBL) Packet switched to circuit switched access handovers in an ims architecture
CN104170455B (zh) * 2012-01-10 2019-04-09 诺基亚通信公司 处理通信系统中的切换请求
CN103313334A (zh) * 2012-03-16 2013-09-18 中国移动通信集团广东有限公司 无线通信方法和基站控制器
US8738014B2 (en) * 2012-06-15 2014-05-27 Telefonaktiebolaget L M Ericsson (Publ) Dynamic VCC assignment
CN109219098B (zh) * 2012-08-07 2021-09-14 华为技术有限公司 切换处理方法及基站
CN102883309B (zh) * 2012-09-29 2016-03-30 捷德（中国）信息科技有限公司 机器到机器m2m通信方法及装置
CN104010324B (zh) * 2013-02-22 2018-04-27 华为技术有限公司 控制服务的方法、移动管理实体和移动交换中心
EP3054723B1 (en) * 2013-11-01 2019-09-04 Huawei Technologies Co., Ltd. Network switching method, device and system
WO2015100608A1 (zh) * 2013-12-31 2015-07-09 华为技术有限公司 一种选择lte网络的方法、设备及系统
ES2761608T3 (es) * 2014-04-15 2020-05-20 Nokia Solutions & Networks Oy Interfuncionamiento con un sistema basado en una portadora
CN107113670B (zh) * 2014-12-30 2020-10-30 Lg 电子株式会社 无线通信系统中执行没有senb改变的menb间切换的方法和装置
US20170085597A1 (en) * 2015-09-18 2017-03-23 Samsung Electronics Co., Ltd. Device and method for merging circuit switched calls and packet switched calls in user equipment
CN109257780B (zh) * 2017-07-14 2021-06-01 华为技术有限公司 网络切换方法及装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101453719A (zh) * 2007-12-07 2009-06-10 华为技术有限公司 实现互联网协议语音业务切换的方法、系统和设备
CN101472313A (zh) * 2007-12-27 2009-07-01 华为技术有限公司 一种语音业务切换方法、系统和装置
CN102461276A (zh) * 2009-06-03 2012-05-16 捷讯研究有限公司 演进分组系统中的语音服务
WO2014036338A2 (en) * 2012-08-31 2014-03-06 Qualcomm Incorporated Selective network parameter configuratons based on network identification of non-ims multimedia applications
CN102984770A (zh) * 2012-12-04 2013-03-20 中国联合网络通信集团有限公司 网络切换方法、移动管理实体、基站和网络系统

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11432208B2 (en) 2017-08-02 2022-08-30 Zte Corporation Network handover method, apparatus and system
JP7025528B2 (ja) 2017-08-02 2022-02-24 中興通訊股▲ふん▼有限公司 ネットワークハンドオーバ方法、装置、およびシステム
JP2020529167A (ja) * 2017-08-02 2020-10-01 中興通訊股▲ふん▼有限公司Ｚｔｅ Ｃｏｒｐｏｒａｔｉｏｎ ネットワークハンドオーバ方法、装置、およびシステム
CN111770587A (zh) * 2019-04-02 2020-10-13 华为技术有限公司 一种数据处理方法、装置及系统
US11991778B2 (en) 2019-04-02 2024-05-21 Huawei Technologies Co., Ltd. Data processing method and apparatus to associate data of a terminal distributed on different network elements
CN111770587B (zh) * 2019-04-02 2023-11-28 华为技术有限公司 一种数据处理方法、装置及系统
US11510267B2 (en) 2019-04-05 2022-11-22 T-Mobile Usa, Inc. Efficient Evolved Packet System (EPS) fallback
US12016070B2 (en) 2019-04-05 2024-06-18 T-Mobile Usa, Inc. Efficient evolved packet system (EPS) fallback
EP3720236A1 (en) * 2019-04-05 2020-10-07 T-Mobile USA, Inc. Efficient evolved packet system (eps) fallback
US11665212B2 (en) 2019-07-16 2023-05-30 T-Mobile Usa, Inc. Timer-initiated fallback
EP3768021A1 (en) * 2019-07-16 2021-01-20 T-Mobile USA, Inc. Timer-initiated fallback
US11284463B2 (en) 2019-07-16 2022-03-22 T-Mobile Usa, Inc. Automatically resetting interrupted network connections
WO2021013353A1 (en) * 2019-07-25 2021-01-28 Telefonaktiebolaget Lm Ericsson (Publ) Fallback during call set-up
CN113709903A (zh) * 2020-05-21 2021-11-26 华为技术有限公司 一种通信方法、设备及系统
CN112073512A (zh) * 2020-09-08 2020-12-11 中国联合网络通信集团有限公司 数据处理方法及设备
CN114449592A (zh) * 2020-10-30 2022-05-06 展讯半导体(成都)有限公司 通信方法、装置、设备及存储介质
CN114449592B (zh) * 2020-10-30 2024-06-07 展讯半导体(成都)有限公司 通信方法、装置、设备及存储介质
CN113115318A (zh) * 2021-03-18 2021-07-13 中国联合网络通信集团有限公司 通信管制方法及装置
CN113115318B (zh) * 2021-03-18 2022-08-12 中国联合网络通信集团有限公司 通信管制方法及装置

Also Published As

Publication number Publication date
CN109257780B (zh) 2021-06-01
CN109257788A (zh) 2019-01-22
CN109041149A (zh) 2018-12-18
CN109041149B (zh) 2020-01-03
CN109257788B (zh) 2021-06-22
CN109257780A (zh) 2019-01-22

Similar Documents

Publication Publication Date Title
JP6724235B2 (ja) ネットワーク登録方法、ネットワークハンドオーバ方法、ネットワーク装置および端末装置
WO2019011107A1 (zh) 网络切换方法及装置
US11497076B2 (en) Service processing method and service processing apparatus
US11412430B2 (en) Network handover method and session management network element
US20190124124A1 (en) Service Processing Method And Apparatus
US20160021580A1 (en) Telecommunication Equipment Measuring Pre-Establishment Service Interruptions
CN109792799A (zh) 一种业务通信方法及设备
WO2019029228A1 (zh) 语音业务的处理方法及装置、存储介质
US10542575B1 (en) Controlling initiation of dedicated bearer setup following failed dedicated bearer setup
WO2011150649A1 (zh) 分组数据网关重分配的方法和装置
JP7516678B2 (ja) ハンドオーバ手順に基づくメッセージ送信方法、装置、機器及びプログラム
JP2024506094A (ja) ハンドオーバ手順に基づくメッセージ送信方法、装置、機器及びプログラム

Legal Events

Date Code Title Description
ENP Entry into the national phase

Ref document number: 2019500561

Country of ref document: JP

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 20197002390

Country of ref document: KR

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 2018815923

Country of ref document: EP

Effective date: 20181221

REG Reference to national code

Ref country code: BR

Ref legal event code: B01A

Ref document number: 112019000557

Country of ref document: BR

ENP Entry into the national phase

Ref document number: 2018298508

Country of ref document: AU

Date of ref document: 20180619

Kind code of ref document: A

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18815923

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 112019000557

Country of ref document: BR

Kind code of ref document: A2

Effective date: 20190111

NENP Non-entry into the national phase

Ref country code: DE