CN117500010A

CN117500010A - Calling method, device and terminal

Info

Publication number: CN117500010A
Application number: CN202210886306.6A
Authority: CN
Inventors: 程思涵; 崇卫微; 吴晓波
Original assignee: Vivo Mobile Communication Co Ltd
Current assignee: Vivo Mobile Communication Co Ltd
Priority date: 2022-07-26
Filing date: 2022-07-26
Publication date: 2024-02-02

Abstract

The application discloses a calling method, a calling device and a calling terminal, which belong to the technical field of communication, and the calling method in the embodiment of the application comprises the following steps: the terminal initiates or receives an IMS call request in a 5G network of a first PLMN, wherein the first PLMN is a roaming PLMN of the terminal; the terminal receives a redirection message sent by a 5G network of the first PLMN; under the condition that a preset condition is met, the terminal reselects to a 4G network of a second PLMN according to the redirection message, sends an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completes a calling process; wherein, the preset conditions include: the ID of the first PLMN is equal to the ID of the particular PLMN.

Description

Calling method, device and terminal

Technical Field

The application belongs to the technical field of communication, and particularly relates to a calling method, a calling device and a calling terminal.

Background

The new air interface carried voice (Voice over New Radio, voNR) is a voice call method based on 5G completely, the call establishment time is shorter, the concurrency of 5G voice and 5G data services is supported, and the high-speed 5G internet surfing can be realized while the call is made.

Public land mobile network (Public Land Mobile Network, abbreviated PLMN), which refers to a set of codes that can uniquely identify a communications carrier, consists of a mobile country code (Mobile Country Code, abbreviated MCC) and a mobile network code (Mobile Network Code, MNC). The PLMN mainly comprises the following types:

(1) HPLMN (Home PLMN ): is the PLMN to which the end user belongs. The MCC and MNC contained in the international mobile subscriber identity (International Mobile Subscriber Identity, abbreviated IMSI) number on the terminal USIM card is identical to the MCC and MNC on the HPLMN, and for a certain subscriber, there is only one PLMN to which it belongs.

(2) EHPLMN (EquivalentHome PLMN ): is the HPLMN that is in the same place as the PLMN currently selected by the terminal. Such as the original network of a certain operator and the new network now, different number segments.

(3) VPLMN (Visited PLMN): a PLMN other than the HPLMN or EHPLMN is the PLMN visited by the end user. The PLMN and MCC, MNC of the IMSI present in the SIM card are not identical. It is also considered that PLMNs other than the home PLMN may all be counted as roaming PLMNs.

The N26 interface is an interface between the 4G core network and the 5G core network, i.e. an interface between the mobility management entity (Mobility Management Entity, MME) and the access and mobility management functions (Access and Mobility Management Function, AMF) of the 5G core network for the inter-operation of 4G and 5G. Whether an N26 interface is supported between networks is optional.

In the case that part of 5G terminals do not support VoNR, their voice services should connect to the 4G network and complete the call through EPS fallback and other technologies. However, since some networks do not deploy the N26 interface and do not support the interoperability (interworking without N) feature that does not use the N26 interface, when these terminals receive the redirection message and reselect to the 4G network, the registration or tracking area update (Tracking Area Update, TAU) procedure is initiated, which causes the IP address to change, and the previous context information is lost, which causes the user to drop call, and affects the user experience.

Disclosure of Invention

The embodiment of the application provides a calling method, a calling device and a terminal, which can solve the problem that a terminal which does not support VoNR in the prior art fails in the redirection fallback process, so that the terminal is dropped.

In a first aspect, a calling method is provided, including:

the terminal initiates or receives an IMS call request in a 5G network of a first PLMN, wherein the first PLMN is a roaming PLMN of the terminal;

the terminal receives a redirection message sent by a 5G network of the first PLMN;

under the condition that a preset condition is met, the terminal reselects to a 4G network of a second PLMN according to the redirection message, sends an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completes a calling process;

Wherein, the preset conditions include: the ID of the first PLMN is equal to the ID of the particular PLMN.

In a second aspect, there is provided a calling device comprising:

a request module, configured to initiate or receive an IMS call request in a 5G network of a first PLMN, where the first PLMN is a roaming PLMN of the terminal;

a receiving module, configured to receive a redirection message sent by a 5G network of the first PLMN;

the processing module is used for reselecting the 4G network to the second PLMN according to the redirection message under the condition that the preset condition is met, sending an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completing a calling process;

In a third aspect, there is provided a terminal comprising a processor and a memory storing a program or instructions executable on the processor, which when executed by the processor, implement the steps of the method as described in the first aspect.

In a fourth aspect, a terminal is provided, including a processor and a communication interface, where the communication interface is configured to initiate or receive an IMS call request in a 5G network of a first PLMN, the first PLMN being a roaming PLMN of the terminal; and receiving a redirection message sent by a 5G network of the first PLMN; under the condition that a preset condition is met, reselecting the 4G network to a second PLMN according to the redirection message, sending an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completing a calling process; wherein, the preset conditions include: the ID of the first PLMN is equal to the ID of the particular PLMN.

In a fifth aspect, there is provided a readable storage medium having stored thereon a program or instructions which when executed by a processor realizes the steps of the method according to the first aspect.

In a sixth aspect, there is provided a chip comprising a processor and a communication interface coupled to the processor for running a program or instructions to implement the method of the first aspect.

In a seventh aspect, there is provided a computer program/program product stored in a storage medium, the computer program/program product being executed by at least one processor to carry out the steps of the method according to the first aspect.

In the embodiment of the application, when the terminal receives the redirection message sent by the 5G network of the roaming PLMN and the ID of the roaming PLMN is equal to the ID of the specific PLMN, the terminal actively reselects to the 4G network of the second PLMN according to the redirection message, sends an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completes the calling process, so that the terminal which does not support VoNR can not interrupt the call when reselecting from the 5G network to the 4G network.

Drawings

Fig. 1 shows a block diagram of a wireless communication system to which embodiments of the present application are applicable;

fig. 2 is a flowchart illustrating steps of a calling method according to an embodiment of the present application;

fig. 3 is a schematic diagram of a handover attachment flow in a call method according to an embodiment of the present application;

fig. 4 shows a schematic structural diagram of a calling device according to an embodiment of the present application;

fig. 5 shows one of schematic structural diagrams of a terminal provided in an embodiment of the present application;

fig. 6 shows a second schematic structural diagram of a terminal according to an embodiment of the present application.

Detailed Description

Technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application are within the scope of the protection of the present application.

The terms first, second and the like in the description and in the claims, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application are capable of operation in sequences other than those illustrated or otherwise described herein, and that the terms "first" and "second" are generally intended to be used in a generic sense and not to limit the number of objects, for example, the first object may be one or more. Furthermore, in the description and claims, "and/or" means at least one of the connected objects, and the character "/" generally means a relationship in which the associated object is an "or" before and after.

It is noted that the techniques described in embodiments of the present application are not limited to long term evolution (Long Term Evolution, LTE)/LTE evolution (LTE-Advanced, LTE-a) systems, but may also be used in other wireless communication systems, such as code division multiple access (Code Division Multiple Access, CDMA), time division multiple access (Time Division Multiple Access, TDMA), frequency division multiple access (Frequency Division Multiple Access, FDMA), orthogonal frequency division multiple access (Orthogonal Frequency Division Multiple Access, OFDMA), single carrier frequency division multiple access (Single-carrier Frequency Division Multiple Access, SC-FDMA), and other systems. The terms "system" and "network" in embodiments of the present application are often interchangeableAlternatively, the described techniques may be used for both the above-mentioned systems and radio technologies, as well as other systems and radio technologies. The following description describes a New air interface (NR) system for purposes of example and uses NR terminology in much of the description that follows, but these techniques are also applicable to applications other than NR system applications, such as generation 6 (6) ^th Generation, 6G) communication system.

Fig. 1 shows a block diagram of a wireless communication system to which embodiments of the present application are applicable. The wireless communication system includes a terminal 11 and a network device 12. The terminal 11 may be a mobile phone, a tablet (Tablet Personal Computer), a Laptop (Laptop Computer) or a terminal-side Device called a notebook, a personal digital assistant (Personal Digital Assistant, PDA), a palm top, a netbook, an ultra-mobile personal Computer (ultra-mobile personal Computer, UMPC), a mobile internet appliance (Mobile Internet Device, MID), an augmented reality (augmented reality, AR)/Virtual Reality (VR) Device, a robot, a Wearable Device (weather Device), a vehicle-mounted Device (VUE), a pedestrian terminal (PUE), a smart home (home Device with a wireless communication function, such as a refrigerator, a television, a washing machine, or a furniture), a game machine, a personal Computer (personal Computer, PC), a teller machine, or a self-service machine, and the Wearable Device includes: intelligent wrist-watch, intelligent bracelet, intelligent earphone, intelligent glasses, intelligent ornament (intelligent bracelet, intelligent ring, intelligent necklace, intelligent anklet, intelligent foot chain etc.), intelligent wrist strap, intelligent clothing etc.. Note that, the specific type of the terminal 11 is not limited in the embodiment of the present application. The network-side device 12 may comprise an access network device or a core network device, wherein the access network device 12 may also be referred to as a radio access network device, a radio access network (Radio Access Network, RAN), a radio access network function or a radio access network element. Access network device 12 may include a base station, a WLAN access point, a WiFi node, or the like, which may be referred to as a node B, an evolved node B (eNB), an access point, a base transceiver station (Base Transceiver Station, BTS), a radio base station, a radio transceiver, a basic service set (Basic Service Set, BSS), an extended service set (Extended Service Set, ESS), a home node B, a home evolved node B, a transmission and reception point (Transmitting Receiving Point, TRP), or some other suitable terminology in the art, and the base station is not limited to a particular technical vocabulary so long as the same technical effect is achieved, and it should be noted that in the embodiments of the present application, only a base station in an NR system is described as an example, and the specific type of the base station is not limited. The core network device may include, but is not limited to, at least one of: core network nodes, core network functions, mobility management entities (Mobility Management Entity, MME), access mobility management functions (Access and Mobility Management Function, AMF), session management functions (Session Management Function, SMF), user plane functions (User Plane Function, UPF), policy control functions (Policy Control Function, PCF), policy and charging rules function units (Policy and Charging Rules Function, PCRF), edge application service discovery functions (Edge Application Server Discovery Function, EASDF), unified data management (Unified Data Management, UDM), unified data repository (Unified Data Repository, UDR), home subscriber server (Home Subscriber Server, HSS), centralized network configuration (Centralized network configuration, CNC), network storage functions (Network Repository Function, NRF), network opening functions (Network Exposure Function, NEF), local NEF (or L-NEF), binding support functions (Binding Support Function, BSF), application functions (Application Function, AF), and the like. In the embodiment of the present application, only the core network device in the NR system is described as an example, and the specific type of the core network device is not limited.

The calling method, the calling device and the calling terminal provided by the embodiment of the application are described in detail through some embodiments and application scenes thereof with reference to the accompanying drawings.

As shown in fig. 2, an embodiment of the present invention provides a calling method, including:

step 201, a terminal initiates or receives an IMS call request in a 5G network of a first PLMN, where the first PLMN is a roaming PLMN of the terminal;

in the embodiment of the present invention, the terminal may be understood as being in a roaming state, specifically: when a cell (or an operator) to which a home PLMN of the terminal belongs does not support 5G services, but an equivalent PLMN belongs to other operators and supports 5G services, the terminal selects to roam into a 5G network of the operator supporting 5G services, that is, the terminal selects an equivalent PLMN supporting 5G, which can be understood as the first PLMN;

step 202, the terminal receives a redirection message sent by a 5G network of the first PLMN;

step 203, when the preset condition is met, the terminal reselects to the 4G network of the second PLMN according to the redirection message, sends an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completes the calling process; wherein, the preset conditions include: the ID of the first PLMN is equal to the ID of the particular PLMN. In the embodiment of the invention, after receiving the redirection message, the terminal checks the network environment, judges whether the first PLMN is the target PLMN, reselects to the 4G network of the second PLMN if the first PLMN is the target PLMN, sends an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completes the calling process; therefore, when the terminal uses IMS voice service, the IP address is kept unchanged when the terminal is switched from the 5G network of the first PLMN to the 4G network of the second PLMN, and the problem of dropped call is avoided.

As an alternative embodiment, the second PLMN is a home PLMN of the terminal.

In other words, after receiving the redirection message, the terminal checks the network environment, judges whether the current roaming PLMN is the target PLMN, reselects to the 4G network of the home PLMN if the current roaming PLMN is the target PLMN, sends an attachment request message carrying a switching instruction to the 4G network of the home PLMN, and completes the calling process; therefore, when the terminal uses IMS voice service, the IP address is kept unchanged when the terminal is switched from the 5G network of the roaming PLMN to the 4G network of the home PLMN, and the problem of dropped call is avoided.

Alternatively, the ID of a specific PLMN may be understood as the ID of a specific PLMN, for example, the ID of a specific PLMN may be an ID of a preset PLMN, an ID of a predefined PLMN, or an ID of a PLMN configured on the network side.

In at least one optional embodiment of the present application, the preset condition further includes:

no N26 interface exists between the core network element of the 5G network of the first PLMN and the core network element of the 4G network of the second PLMN;

the 5G network of the first PLMN does not support first interoperability with the 4G network of the second PLMN, the first interoperability being interoperability without using the N26 interface (i.e. the 5G network of the first PLMN does not support interworking without N).

In other words, in the embodiment of the present application, when the roaming PLMN of the terminal does not support the N26 interface or interworking without N interface, the terminal actively determines and initiates the handover attach procedure, so that the terminal that does not support VoNR can reselect from 5G to 4G without interrupting the call.

Optionally, the ID of the specific PLMN is preconfigured in the terminal.

Optionally, the ID of the specific PLMN is received from a core network element of the home PLMN 4G network when the terminal registers with the home PLMN 4G network.

Optionally, the ID of the specific PLMN is received from a core network element of the home PLMN 5G network when the terminal registers with the home PLMN 5G network.

Optionally, the ID of the specific PLMN is preconfigured to the terminal by the network side.

As an optional embodiment, the terminal includes a 5G protocol stack and a 4G protocol stack, where the 5G protocol stack and the 4G protocol stack include a corresponding RRC layer and NAS layer, respectively; accordingly, in step 203, the terminal sends an attach request message carrying a handover indication to the 4G network of the second PLMN, including:

the RRC layer of the 5G protocol stack of the terminal sends first information to a NAS layer (such as a Mobility Management (MM) module of the NAS layer) of the 5G protocol stack, wherein the first information is used for determining that the terminal receives a redirection message by the NAS layer;

Under the condition that the preset condition is met, the NAS layer of the 5G protocol stack sends second information to the NAS layer of the 4G protocol stack, wherein the second information is used for determining that an attachment request message carrying a switching instruction is sent to a 4G network of the second PLMN by the NAS layer of the 4G protocol stack;

and the NAS layer of the 4G protocol stack sends an attachment request message carrying a switching instruction to the 4G network of the second PLMN.

As shown in fig. 3, the handover attach procedure in the terminal call process includes:

step 0: the UE registers with the 5G network.

Step 1: the UE receives a Redirection (Redirection) request (via RRC connection release message and carrying Redirection indication information) that instructs the UE to redirect.

Step 2, the UE decides to initiate a Handover Attach (Handover Attach) procedure; the method specifically comprises the following steps:

step 2a: the RRC layer of the 5G protocol stack receives an RRC message containing indication information of redirection.

Step 2b: the RRC layer of the 5G protocol stack sends the redirection indication to the mobility management MM module of the NAS layer.

Step 2c: and the NAS-MM module receives the redirected indication information, checks the network environment and judges whether a Handover Attach procedure is initiated. Specifically, the MM module checks whether the network PLMN currently in place is a designated PLMN. If so, a handover attach request is sent to the NAS layer in the 4G protocol stack.

Step 2d: the 5G NAS layer MM module sends a Handover attach request to the 4G NAS layer, and the Handover attach flow is initiated by the terminal 4G protocol stack related module.

Step 3: the UE sends an attach request to the 4G core network, and carries a Handover identifier in the request.

Step 4: the UE and the 4G core network perform a handover attach procedure.

In at least one embodiment of the present application, in order to reduce the time consumption of searching for the 4G network during the use of voice services, the method further includes, before step 202:

the terminal searches the 4G cell of the second PLMN to obtain the frequency point information of the 4G cell of the second PLMN which can reside;

accordingly, step 203 includes:

the terminal reselects a target cell of the 4G network of the second PLMN according to the obtained frequency point information of the 4G cell and the redirection message;

and the terminal sends an attachment request message carrying a switching instruction through a base station corresponding to a target cell of the 4G network.

As an alternative embodiment, the terminal includes: a first card that is in use or is about to initiate an IMS message, and, in the event that a second card is not currently in use or has an idle radio frequency or has an idle antenna, the terminal performs a search for a 4G cell of the second PLMN, comprising:

And the terminal uses the radio frequency and/or the antenna of the second card to search the 4G cell of the second PLMN.

For example, for a terminal (UE) with dual-card dual-antenna, in roaming situation, the UE starts to search for the home PLMN 4G cell using the radio frequency of the second card (may also be called a secondary card), and obtains the frequency point information of the home PLMN 4G cell. And after receiving the Redirection message, the UE actively transmits an attachment request message carrying a switching instruction to be connected to the 4G network of the home PLMN by utilizing the frequency point information of the searched 4G cell of the home PLMN.

As another example, the terminal comprises two SIM cards or USIM cards, in which case card 1 is or is ready to initiate/receive an IMS request, card 2 is in an idle state or card 2 has no service in progress in roaming situations. The terminal can use the radio frequency of the card 2 to search the home PLMN 4G cell, and obtain the frequency point information of the home PLMN 4G cell. Alternatively, card 2 is or is ready to initiate/receive an IMS request, card 1 is in an idle state or card 1 has no service in progress. The terminal can use the radio frequency of the card 1 to search the home PLMN 4G cell, and obtain the frequency point information of the home PLMN 4G cell. And after receiving the Redirection message, the UE actively transmits an attachment request message carrying a switching instruction to be connected to the 4G network of the home PLMN by utilizing the frequency point information of the searched 4G cell of the home PLMN.

As another alternative embodiment, the searching of the 4G cell of the second PLMN by the terminal includes:

under the condition that the first condition is met, the terminal searches a second PLMN 4G cell; the first condition includes at least one of:

the terminal initiates an IMS call request in a 5G network of a first PLMN;

the terminal receives an IMS call request in a 5G network of a first PLMN;

starting a dialing interface of the terminal;

starting an address book of the terminal;

and starting an application program corresponding to the voice service in the terminal.

In other words, the first condition is an initiation condition for the terminal to perform a search for the second PLMN 4G cell. For example, if the terminal initiates an IMS call request within the 5G network of the first PLMN, the terminal performs a search for a second PLMN 4G cell; for another example, if the user initiates a dial interface of the terminal, the terminal performs a search of the second PLMN 4G cell; not enumerated here.

In summary, in the embodiment of the present application, when the terminal receives a redirection message sent by the 5G network of the roaming PLMN and the ID of the roaming PLMN is equal to the ID of the specific PLMN, the terminal actively reselects to the 4G network of the second PLMN according to the redirection message, sends an attach request message carrying a handover instruction to the 4G network of the second PLMN, and completes the call process, so that the terminal that does not support VoNR can perform a call without interruption when reselecting from the 5G network to the 4G network.

According to the calling method provided by the embodiment of the application, the execution subject can be a calling device. In the embodiment of the present application, a calling device executes a calling method as an example, and the calling device provided in the embodiment of the present application is described.

As shown in fig. 4, the embodiment of the present application further provides a calling device 400, including:

a request module 401, configured to initiate or receive an IMS call request in a 5G network of a first PLMN, where the first PLMN is a roaming PLMN of the terminal;

a receiving module 402, configured to receive a redirection message sent by a 5G network of the first PLMN;

a processing module 403, configured to reselect to a 4G network of a second PLMN according to the redirection message when a preset condition is met, send an attach request message carrying a handover instruction to the 4G network of the second PLMN, and complete a call process;

As an alternative embodiment, the second PLMN is a home PLMN of the terminal.

As an optional embodiment, the preset condition further includes:

The 5G network of the first PLMN does not support interoperability without using the N26 interface.

As an alternative embodiment, the ID of the specific PLMN is preconfigured in the terminal; or,

the ID of the specific PLMN is received from a core network element of the home PLMN4G network when the terminal registers in the home PLMN4G network; or,

the ID of the specific PLMN is received from a core network element of the home PLMN5G network when the terminal registers with the home PLMN5G network.

As an alternative embodiment, in case the terminal comprises a 5G protocol stack and a 4G protocol stack, the processing module is further configured to:

sending first information to a non-access NAS layer of a 5G protocol stack through a Radio Resource Control (RRC) layer of the 5G protocol stack of the terminal, wherein the first information is used for determining that the terminal receives a redirection message by the NAS layer;

sending second information to the NAS layer of the 4G protocol stack through the NAS layer of the 5G protocol stack under the condition that the preset condition is met, wherein the second information is used for determining that an attachment request message carrying a switching instruction is sent to a 4G network of the second PLMN by the NAS layer of the 4G protocol stack;

And sending an attachment request message carrying a switching instruction to the 4G network of the second PLMN through the NAS layer of the 4G protocol stack.

As an alternative embodiment, the apparatus further comprises:

and the searching module is used for searching the 4G cell of the second PLMN to obtain the frequency point information of the 4G cell of the second PLMN which can reside.

As an alternative embodiment, the processing module is further configured to:

reselecting a target cell of the 4G network of the second PLMN according to the obtained frequency point information of the 4G cell and the redirection message;

and sending an attachment request message carrying a switching instruction through a base station corresponding to the target cell of the 4G network.

As an alternative embodiment, the search module includes:

the first searching sub-module is used for searching the second PLMN 4G cell under the condition that the first condition is met; the first condition includes at least one of:

the terminal initiates an IMS call request in a 5G network of a first PLMN;

the terminal receives an IMS call request in a 5G network of a first PLMN;

starting a dialing interface of the terminal;

starting an address book of the terminal;

As an alternative embodiment, the method comprises the following steps at the terminal: the search module comprises:

and the second searching sub-module is used for searching the 4G cell of the second PLMN by using the radio frequency and/or the antenna of the second card.

It should be noted that, the calling device provided in the embodiments of the present application is a device capable of executing the foregoing calling method, and all embodiments of the foregoing calling method are applicable to the device, and the same or similar beneficial effects can be achieved.

The calling device in the embodiment of the application may be an electronic device, for example, an electronic device with an operating system, or may be a component in the electronic device, for example, an integrated circuit or a chip. The electronic device may be a terminal, or may be other devices than a terminal. By way of example, terminals may include, but are not limited to, the types of terminals 11 listed above, other devices may be servers, network attached storage (Network Attached Storage, NAS), etc., and embodiments of the application are not specifically limited.

The calling device provided in the embodiment of the present application can implement each process implemented by the embodiments of the methods of fig. 1 to 3, and achieve the same technical effects, so that repetition is avoided, and no further description is given here.

Optionally, as shown in fig. 5, the embodiment of the present application further provides a terminal 500, including a processor 501 and a memory 502, where the memory 502 stores a program or an instruction that can be executed on the processor 501, and the program or the instruction implements each step of the foregoing call method embodiment when executed by the processor 501, and the steps can achieve the same technical effect, so that repetition is avoided, and no redundant description is provided herein.

The embodiment of the application also provides a terminal, which comprises a processor and a communication interface, wherein the communication interface is used for initiating or receiving an IMS call request in a 5G network of a first PLMN, and the first PLMN is a roaming PLMN of the terminal; and receiving a redirection message sent by a 5G network of the first PLMN; under the condition that a preset condition is met, reselecting the 4G network to a second PLMN according to the redirection message, sending an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completing a calling process; wherein, the preset conditions include: the ID of the first PLMN is equal to the ID of the particular PLMN. The terminal embodiment corresponds to the terminal-side method embodiment, and each implementation process and implementation manner of the method embodiment can be applied to the terminal embodiment, and the same technical effects can be achieved. Specifically, fig. 6 is a schematic hardware structure of a terminal for implementing an embodiment of the present application.

The terminal 600 includes, but is not limited to: at least some of the components of the radio frequency unit 601, the network module 602, the audio output unit 603, the input unit 604, the sensor 605, the display unit 606, the user input unit 607, the interface unit 608, the memory 609, and the processor 610, etc.

Those skilled in the art will appreciate that the terminal 600 may further include a power source (e.g., a battery) for powering the various components, and the power source may be logically coupled to the processor 610 by a power management system so as to perform functions such as managing charging, discharging, and power consumption by the power management system. The terminal structure shown in fig. 6 does not constitute a limitation of the terminal, and the terminal may include more or less components than shown, or may combine certain components, or may be arranged in different components, which will not be described in detail herein.

It should be understood that in the embodiment of the present application, the input unit 604 may include a graphics processing unit (Graphics Processing Unit, GPU) 6041 and a microphone 6042, and the graphics processor 6041 processes image data of still pictures or video obtained by an image capturing apparatus (such as a camera) in a video capturing mode or an image capturing mode. The display unit 606 may include a display panel 6061, and the display panel 6061 may be configured in the form of a liquid crystal display, an organic light emitting diode, or the like. The user input unit 607 includes at least one of a touch panel 6071 and other input devices 6072. The touch panel 6071 is also called a touch screen. The touch panel 6071 may include two parts of a touch detection device and a touch controller. Other input devices 6072 may include, but are not limited to, a physical keyboard, function keys (e.g., volume control keys, switch keys, etc.), a trackball, a mouse, a joystick, and so forth, which are not described in detail herein.

In this embodiment, after receiving downlink data from the network side device, the radio frequency unit 601 may transmit the downlink data to the processor 610 for processing; in addition, the radio frequency unit 601 may send uplink data to the network side device. Typically, the radio frequency unit 601 includes, but is not limited to, an antenna, an amplifier, a transceiver, a coupler, a low noise amplifier, a duplexer, and the like.

The memory 609 may be used to store software programs or instructions and various data. The memory 609 may mainly include a first storage area storing programs or instructions and a second storage area storing data, wherein the first storage area may store an operating system, application programs or instructions (such as a sound playing function, an image playing function, etc.) required for at least one function, and the like. Further, the memory 609 may include volatile memory or nonvolatile memory, or the memory 609 may include both volatile and nonvolatile memory. The nonvolatile Memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable EPROM (EEPROM), or a flash Memory. The volatile memory may be random access memory (Random Access Memory, RAM), static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (ddr SDRAM), enhanced SDRAM (Enhanced SDRAM), synchronous DRAM (SLDRAM), and Direct RAM (DRRAM). Memory 609 in the present embodiment includes, but is not limited to, these and any other suitable types of memory.

The processor 610 may include one or more processing units; optionally, the processor 610 integrates an application processor that primarily processes operations involving an operating system, user interface, application programs, etc., and a modem processor that primarily processes wireless communication signals, such as a baseband processor. It will be appreciated that the modem processor described above may not be integrated into the processor 610.

The radio frequency unit 601 is configured to initiate or receive an IMS call request in a 5G network of a first PLMN, where the first PLMN is a roaming PLMN of the terminal; and receiving a redirection message sent by a 5G network of the first PLMN; under the condition that a preset condition is met, reselecting the 4G network to a second PLMN according to the redirection message, sending an attachment request message carrying a switching instruction to the 4G network of the second PLMN, and completing a calling process; wherein, the preset conditions include: the ID of the first PLMN is equal to the ID of the specific PLMN

It should be noted that, the terminal provided in the embodiment of the present application is a terminal capable of executing the foregoing call method, and all embodiments of the foregoing call method are applicable to the terminal, and the same or similar beneficial effects can be achieved.

The embodiment of the present application further provides a readable storage medium, where a program or an instruction is stored, and when the program or the instruction is executed by a processor, the program or the instruction realizes each process of the foregoing calling method embodiment, and the same technical effects can be achieved, so that repetition is avoided, and no further description is given here.

Wherein the processor is a processor in the terminal described in the above embodiment. The readable storage medium includes computer readable storage medium such as computer readable memory ROM, random access memory RAM, magnetic or optical disk, etc.

The embodiment of the application further provides a chip, the chip includes a processor and a communication interface, the communication interface is coupled with the processor, and the processor is used for running a program or an instruction, implementing each process of the above-mentioned calling method embodiment, and achieving the same technical effect, so as to avoid repetition, and no redundant description is provided herein.

It should be understood that the chips referred to in the embodiments of the present application may also be referred to as system-on-chip chips, or the like.

The embodiments of the present application further provide a computer program/program product, where the computer program/program product is stored in a storage medium, and the computer program/program product is executed by at least one processor to implement each process of the foregoing embodiments of the calling method, and the same technical effects are achieved, so that repetition is avoided and detailed description is omitted herein.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of the present application is not limited to performing the functions in the order shown or discussed, but may also include performing the functions in a substantially simultaneous manner or in an opposite order depending on the functions involved, e.g., the described methods may be performed in an order different from that described, and various steps may also be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

From the above description of the embodiments, it will be clear to those skilled in the art that the above-described embodiment method may be implemented by means of software plus a necessary general hardware platform, but of course may also be implemented by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solutions of the present application may be embodied essentially or in a part contributing to the prior art in the form of a computer software product stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk), comprising several instructions for causing a terminal (which may be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to perform the method described in the embodiments of the present application.

The embodiments of the present application have been described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those of ordinary skill in the art without departing from the spirit of the present application and the scope of the claims, which are also within the protection of the present application.

Claims

1. A method of calling, comprising:

2. The method of claim 1, wherein the second PLMN is a home PLMN of the terminal.

3. The method of claim 1, wherein the preset conditions further comprise:

the 5G network of the first PLMN does not support a first interoperation with the 4G network of the second PLMN, the first interoperation being an interoperation that does not use an N26 interface.

4. The method of claim 1, wherein the step of determining the position of the substrate comprises,

The ID of the specific PLMN is preconfigured in the terminal; or,

5. The method according to any of claims 1 to 4, wherein, in case the terminal comprises a 5G protocol stack and a 4G protocol stack, the terminal sends an attach request message carrying a handover indication to the 4G network of the second PLMN, comprising:

the Radio Resource Control (RRC) layer of the 5G protocol stack of the terminal sends first information to a non-access NAS layer of the 5G protocol stack, wherein the first information is used for determining that the terminal receives a redirection message by the NAS layer;

6. The method according to claim 1 or 2, wherein before the terminal receives the redirection message sent by the 5G network of the first PLMN, the method further comprises:

and the terminal searches the 4G cell of the second PLMN to obtain the frequency point information of the 4G cell of the second PLMN which can reside.

7. The method of claim 6, wherein the terminal reselects to a 4G network of a second PLMN based on the redirection message, and wherein sending an attach request message carrying a handover indication to the 4G network of the second PLMN comprises:

8. The method of claim 6, wherein the terminal performs a search for a 4G cell of the second PLMN, comprising:

the terminal initiates an IMS call request in a 5G network of a first PLMN;

The terminal receives an IMS call request in a 5G network of a first PLMN;

starting a dialing interface of the terminal;

starting an address book of the terminal;

9. The method of claim 6, wherein the method comprises, at the terminal: a first card that is in use or is about to initiate an IMS message, and, in the event that a second card is not currently in use or has an idle radio frequency or has an idle antenna, the terminal performs a search for a 4G cell of the second PLMN, comprising:

10. A calling device applied to a terminal, comprising:

11. The apparatus of claim 10, wherein the second PLMN is a home PLMN of the terminal.

12. The apparatus of claim 10, wherein the preset conditions further comprise:

13. The apparatus of claim 10, wherein the device comprises a plurality of sensors,

the ID of the specific PLMN is preconfigured in the terminal; or,

14. The apparatus according to any of claims 10 to 13, wherein, in case the terminal comprises a 5G protocol stack and a 4G protocol stack, the processing module is further configured to:

when the NAS layer of the 5G protocol stack determines that the first PLMN ID is equal to the ID of the specific PLMN, sending second information to the NAS layer of the 4G protocol stack through the NAS layer of the 5G protocol stack, wherein the second information is used for determining that an attachment request message carrying a switching instruction is sent to a 4G network of the second PLMN by the NAS layer of the 4G protocol stack.

15. The apparatus according to claim 10 or 11, characterized in that the apparatus further comprises:

16. The apparatus of claim 15, wherein the processing module is further configured to:

17. The apparatus of claim 15, wherein the search module comprises:

the terminal initiates an IMS call request in a 5G network of a first PLMN;

the terminal receives an IMS call request in a 5G network of a first PLMN;

starting a dialing interface of the terminal;

starting an address book of the terminal;

18. The apparatus of claim 15, wherein the apparatus comprises, at the terminal: the search module comprises:

19. A terminal comprising a processor and a memory storing a program or instructions executable on the processor, which when executed by the processor, performs the steps of the calling method of any of claims 1 to 9.

20. A readable storage medium, characterized in that the readable storage medium has stored thereon a program or instructions which, when executed by a processor, implement the steps of the calling method according to any of claims 1-9.