WO2024099139A1

WO2024099139A1 - Calling method and apparatus, first core network device, and third core network device

Info

Publication number: WO2024099139A1
Application number: PCT/CN2023/127756
Authority: WO
Inventors: 程思涵
Original assignee: 维沃移动通信有限公司
Priority date: 2022-11-08
Filing date: 2023-10-30
Publication date: 2024-05-16
Also published as: CN118018997A

Abstract

The present application discloses a calling method and apparatus, a first core network device, and a third core network device, and belongs to the technical field of communication. The calling method comprises: a first core network device receiving a first call request, the first call request being used for requesting to establish a target service for a first terminal, the first call request comprising a first value, and the first value being a value of a target parameter corresponding to the target service; when the first value does not match a second value, the first core network device executes any one of the following items: sending a call response to the first terminal, the call response comprising the second value; sending a second call request to a second terminal, the second terminal being a call receiver corresponding to the first call request, and the second call request comprising the second value; wherein the second value is the value of a target parameter supported by a roaming network providing the service to the first terminal.

Description

Calling method, device, first core network device and third core network device

This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 8, 2022, with application number 202211394379.X and application name “Calling method, apparatus, first core network device and third core network device”, all contents of which are incorporated by reference in this application.

Technical Field

The present application belongs to the field of communication technology, and specifically relates to a calling method, an apparatus, a first core network device, and a third core network device.

Background technique

Different operators have different support for voice. For example, the guaranteed bit rates (GBR) of voice supported by mobile network operators (MNO) A, B, and C are 64 kbps, 156 kbps, and 512 kbps, respectively, that is, the upper limit of GBR used by MNO A is equal to 64 kbps; the upper limit of GBR used by MNO B is equal to 156 kbps; and the upper limit of GBR used by MNO C is equal to 512 kbps. For example, when a terminal (e.g., user equipment (UE)) served by MNO C roams to MNO A, the terminal will initiate an IP Multimedia Subsystem (IMS) session request and establish a voice bearer with a GBR of 512 kbps according to the stored configuration of MNO C.

In the related technology, when MNOA establishes a voice bearer according to the negotiation result of the IMS layer, since MNOA only supports the establishment of voice bearers with a GBR upper limit of 64kbps, the core network mobility management entity (Mobility Management Entity, MME) of the fourth generation mobile communication technology (4th Generation Mobile Communication Technology, 4G)/fifth generation mobile communication technology (5th Generation Mobile Communication Technology, 5G) or the session management function (Visited Session Management Function, V-SMF) of the roaming network will reject the voice bearer establishment request, resulting in the failure of voice bearer establishment and the user being unable to use voice services in the roaming area.

Summary of the invention

The embodiments of the present application provide a calling method, an apparatus, a first core network device and a third core network device, which can solve the problem of how to establish voice services for users in a roaming area.

In a first aspect, a calling method is provided, the method comprising:

The first core network device receives a first call request, where the first call request is used to request to establish a target service for the first terminal, and the first call request includes a first value, where the first value is a value of a target parameter corresponding to the target service;

When the first value does not match the second value, the first core network device performs any one of the following:

Sending a call response to the first terminal, where the call response includes the second value;

Sending a second call request to a second terminal, where the second terminal is a call recipient corresponding to the first call request, and the second call request includes the second value;

The second value is the corresponding value of the target service supported by the roaming network providing service to the first terminal. The value of the target parameter.

In a second aspect, a calling method is provided, the method comprising:

The third core network device sends a first call request to the first core network device; the first call request is used to establish a target service for the first terminal, the first call request includes a first value, and the first value is the value of a target parameter corresponding to the target service; the first call request also includes second information; the second information includes at least one of the following:

Indication information, used to indicate that the first terminal is in roaming state;

A first public land mobile network identifier PLMN ID, wherein the first PLMN ID is a PLMN ID of a roaming location network;

The second value is a value of a target parameter corresponding to the target service supported by a roaming network providing services to the first terminal.

In a third aspect, a calling device is provided, the device comprising:

A first receiving module, configured to receive a first call request, wherein the first call request is used to request to establish a target service for a first terminal, wherein the first call request includes a first value, and the first value is a value of a target parameter corresponding to the target service;

A first sending module is configured to, when the first value does not match the second value, perform any of the following:

The second value is a value of a target parameter corresponding to the target service supported by the roaming network providing service to the first terminal.

In a fourth aspect, a calling device is provided, the device comprising:

The second sending module is used to send a first call request to the first core network device; the first call request is used to establish a target service for the first terminal, the first call request includes a first value, and the first value is the value of a target parameter corresponding to the target service; the first call request also includes second information; the second information includes at least one of the following:

In a fifth aspect, a first core network device is provided, which includes a processor and a memory, wherein the memory stores programs or instructions that can be run on the processor, and when the program or instructions are executed by the processor, the steps of the calling method described in the first aspect are implemented.

In a sixth aspect, a first core network device is provided, including a processor and a network interface, wherein: the network interface is used to receive a first call request, the first call request is used to request to establish a target service for a first terminal, the first call request includes a first value, and the first value is the value of a target parameter corresponding to the target service; when the first value does not match the second value, any of the following is performed: sending a call response to the first terminal, the call response The call response includes the second value; a second call request is sent to a second terminal, the second terminal is the call recipient corresponding to the first call request, and the second call request includes the second value; wherein the second value is the value of the target parameter corresponding to the target service supported by the roaming network providing service to the first terminal.

In the seventh aspect, a third core network device is provided, which includes a processor and a memory, wherein the memory stores programs or instructions that can be run on the processor, and when the program or instructions are executed by the processor, the steps of the communication processing method described in the second aspect are implemented.

In the eighth aspect, a third core network device is provided, comprising a processor and a network interface, wherein: the network interface is used to send a first call request to a first core network device; the first call request is used to establish a target service for a first terminal, the first call request includes a first value, and the first value is the value of a target parameter corresponding to the target service; the first call request also includes second information; the second information includes at least one of the following: indication information, used to indicate that the first terminal is in a roaming state; a first public land mobile network identifier PLMN ID, the first PLMN ID is the PLMN ID of a roaming network; a second value, the second value is the value of a target parameter corresponding to the target service supported by the roaming network providing services to the first terminal.

In the ninth aspect, a calling system is provided, comprising: a first terminal, a second terminal, a first core network device and a third core network device, wherein the first core network device can be used to execute the steps of the method described in the first aspect, and the third core network device can be used to execute the steps of the method described in the second aspect.

In the tenth aspect, a readable storage medium is provided, on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of the method described in the first aspect are implemented, or the steps of the method described in the second aspect are implemented.

In the eleventh aspect, a chip is provided, comprising a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run a program or instruction to implement the method described in the first aspect, or to implement the method described in the second aspect.

In the twelfth aspect, a computer program/program product is provided, wherein 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 the steps of the method described in the first aspect, or to implement the steps of the method described in the second aspect.

In an embodiment of the present application, after the first core network device receives a first call request for establishing a target service for the first terminal, if the first value corresponding to the target service requested to be established does not match the second value supported by the roaming network, the first core network device sends a call response carrying the second value to the first terminal, so that the first terminal modifies the parameters corresponding to the target service based on the second value and then initiates the call request again, thereby successfully establishing a voice service for the user in the roaming area; and/or the first core network device sends a second call request carrying the second value to the call recipient, so that the call recipient establishes the target service based on the second value, thereby successfully establishing a voice service for the user in the roaming area. In this way, the user experience can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a wireless communication system applicable to an embodiment of the present application;

FIG2 is a schematic diagram of establishing a voice bearer between UE-1 and UE-2 in the prior art;

FIG3 is a flowchart of a calling method according to an embodiment of the present application;

FIG4 is a second flow chart of a calling method provided in an embodiment of the present application;

FIG5 is a schematic diagram of a process in which UE-1 initiates a registration request according to an embodiment of the present application;

FIG6 is a schematic diagram of a process of establishing a voice bearer between UE-1 and UE-2 provided in an embodiment of the present application;

FIG. 7 is a second schematic diagram of a process in which UE-1 initiates a registration request according to an embodiment of the present application;

FIG8 is a second schematic diagram of a process of establishing a voice bearer between UE-1 and UE-2 provided in an embodiment of the present application;

FIG. 9 is a schematic diagram of a third process of establishing a voice bearer between UE-1 and UE-2 according to an embodiment of the present application;

FIG10 is a schematic diagram of a structure of a calling device according to an embodiment of the present application;

FIG11 is a second schematic diagram of the structure of a calling device provided in an embodiment of the present application;

FIG12 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application;

FIG13 is a schematic diagram of the structure of the core network device provided in an embodiment of the present application.

Detailed ways

The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of this application.

The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, but not to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first" and "second" are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and/or" in the specification and claims represents at least one of the connected objects, and the character "/" generally indicates that the objects associated with each other are in an "or" relationship. The term "indication" in the specification and claims of the present application can be either an explicit indication or an implicit indication. Among them, an explicit indication can be understood as the sender explicitly notifying the receiver of the operation or request result to be performed in the indication sent; an implicit indication can be understood as the receiver making a judgment based on the indication sent by the sender and determining the operation or request result to be performed based on the judgment result.

It is worth noting that the technology described in the embodiments of the present application is not limited to the Long Term Evolution (LTE)/LTE-Advanced (LTE-A) system, but can also be used in other wireless communication systems, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single-carrier Frequency Division Multiple Access (SC-FDMA) and other systems. The terms "system" and "network" in the embodiments of the present application are often used interchangeably, and the described technology can be used for the above-mentioned systems and radio technologies as well as other systems and radio technologies. The following description describes a new radio (NR) system for example purposes, and NR terms are used in most of the following descriptions, but these technologies can also be applied to communication systems other than NR system applications, such as the ^6th Generation (6G) communication system.

FIG. 1 is a schematic diagram of a wireless communication system to which an embodiment of the present application can be applied. The wireless communication system shown in FIG. 1 includes a terminal 11 and a network-side device 12 . Among them, the terminal 11 can be a mobile phone, a tablet computer (Tablet Personal Computer), a laptop computer (Laptop Computer) or a notebook computer, a personal digital assistant (Personal Digital Assistant, PDA), a handheld computer, a netbook, an ultra-mobile personal computer (ultra-mobile personal computer, UMPC), a mobile Internet device (Mobile Internet Device, MID), augmented reality (augmented reality, AR)/virtual reality (virtual reality, VR) equipment, a robot, a wearable device (Wearable Device), a vehicle-mounted device (VUE), a pedestrian terminal (PUE), a smart home (home appliances with wireless communication functions, such as refrigerators, televisions, washing machines or furniture, etc.), a game console, a personal computer (personal computer, PC), an ATM or a self-service machine and other terminal side devices, and the wearable devices include: smart watches, smart bracelets, smart headphones, smart glasses, smart jewelry (smart bracelets, smart bracelets, smart rings, smart necklaces, smart anklets, smart anklets, etc.), smart wristbands, smart clothing, etc. In addition to the above-mentioned terminal devices, it can also be a chip in the terminal, such as a modem chip, a system-on-chip (SoC). It should be noted that the specific type of the terminal 11 is not limited in the embodiment of the present application.

The network side device 12 may include an access network device or a core network device, wherein the access network device may also be referred to as a radio access network device, a radio access network (RAN), a radio access network function or a radio access network unit. The access network device may include a base station, a WLAN access point or a WiFi node, etc. The base station may be referred to as a node B, an evolved node B (eNB), an access point, a base transceiver station (BTS), a radio base station, a radio transceiver, a basic service set (BSS), an extended service set (ESS), a home B node, a home evolved B node, a transmitting and receiving point (TRP) or some other appropriate term in the field, as long as the same technical effect is achieved, the base station is not limited to a specific technical vocabulary, it should be noted that in the embodiment of the present application, only the base station in the NR system is used as an example for introduction, and the specific type of the base station is not limited. The core network equipment may include but is not limited to at least one of the following: core network nodes, core network functions, mobility management entity (Mobility Management Entity, MME), access mobility management function (Access and Mobility Management Function, AMF), session management function (Session Management Function, SMF), user plane function (User Plane Function, UPF), policy control function (Policy Control Function, PCF), policy and charging rules function unit (Policy and Charging Rules Function, PCRF), edge application service discovery function (Edge Application Server Discovery Function, EASDF), unified data management (Unified Data Management, UDM), unified data repository (Unified Data Repos itory, UDR), Home Subscriber Server (HSS), Centralized network configuration (CNC), Network Repository Function (NRF), Network Exposure Function (NEF), Local NEF (L-NEF), Binding Support Function (BSF), Application Function (AF), Location Management Function (LMF), Enhanced Serving Mobile Location Centre (E-SMLC), Network data analytics function (NWDAF), etc. It should be noted that in the embodiments of the present application, only the core network device in the NR system is taken as an example for introduction, and the specific type of the core network device is not limited.

In order to more clearly understand the technical solutions provided by the embodiments of the present application, some relevant background knowledge is first introduced. The knowledge is introduced as follows.

Refer to Figure 2, which is a schematic diagram of establishing a voice bearer between UE-1 and UE-2 in the prior art. Figure 2 illustrates the process of establishing a voice bearer between UE-1 and UE-2. In the scenario where UE-1 roams to a Visit Public Land Mobile Network (VPLMN) in a roaming location, UE-1 and UE-2 make a voice call. The specific steps are as follows:

Step 1: UE-1 establishes a protocol data unit (PDU) session in the roaming network, using the AMF and V-SMF of the roaming network.

Step 2: UE-1 initiates an IMS establishment request through a Session Initiation Protocol (SIP) invite message. The requested session description (SDP) carries the information of the voice media to be established and a voice bearer with a GBR of 512 kbps is requested to be established through b=AS:512.

Step 3: The Proxy-Call Session Control Function (P-CSCF) sends the invite message to UE-2 through the Serving-Call Session Control Function (S-CSCF).

It should be noted that the P-CSCF and S-CSCF in the figure are both IMS network elements that provide services for UE-1, and the IMS network element that provides services for UE-2 is not shown.

Step 4: UE-2 replies with a SIP 183 message through S-CSCF, which contains an SDP answer.

Step 5: P-CSCF sends a Hyper Text Transfer Protocol (HTTP) notification (POST) request (Request) to the Policy Control Function (PCF) providing services for UE-1. The request carries the media description information (media info) negotiated through SDP. The media description information is obtained based on the SDP answer message, which contains information that 512kbps needs to be used.

Note: PCF is a 5G network element, and its corresponding 4G network element is PCRF.

Step 6: PCF sends a request (i.e., SM policy association modification) to the home SMF of UE-1, i.e., H-SMF, requesting to establish a voice bearer. The request carries the Quality of Service (QoS) parameters of the voice bearer to be established, including the information that the GBR is 512kbps.

Step 7: H-SMF sends a request to V-SMF;

That is, Nsmf_PDU session update request (Nsmf_PDUSession_Update Request), which includes QoS parameters.

Step 8: V-SMF determines that the roaming network cannot support 512kbps GBR bearer based on the requested QoS parameters and the QoS parameters it can support, so V-SMF sends a rejection message to H-SMF; that is, Nsmf_PDU session rejection (Nsmf_PDUSession_Reject).

Step 9: H-SMF sends a rejection message to PCF, that is, initiates SM policy association reject (SM policy association reject).

Step 10: The PCF sends a rejection message to the P-CSCF.

Step 11: P-CSCF sends a bye message to UE-1 to terminate the call.

Step 12: P-CSCF sends a bye message to UE-2 to terminate the call.

In the process shown in FIG. 2 , when UE-1 is in a roaming network, since the parameters of the voice bearers supported by the home network and the roaming network are inconsistent, the voice bearer establishment fails, causing the user to be unable to use voice services in the roaming area.

The calling method, apparatus, first core network device and third core network device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings through some embodiments and their application scenarios.

FIG. 3 is a flowchart of a calling method according to an embodiment of the present application. As shown in FIG. 3 , the method includes steps 301-302; wherein:

Step 301: A first core network device receives a first call request, where the first call request is used to request establishment of a target service for a first terminal. The first call request includes a first value, which is a value of a target parameter corresponding to the target service.

First of all, it should be noted that the embodiments of the present application can be applied to scenarios where two communicating parties make calls; core network devices include but are not limited to the types of network side devices 12 listed above, and the present application does not limit this.

In the related art, when a terminal is in a roaming network, the terminal cannot make or receive voice calls due to the inconsistency of parameters supported by the home network and the roaming network. Therefore, in order to successfully establish voice communication between the two communicating parties, in this embodiment, the first core network device needs to receive a first call request for requesting to establish a target service for the first terminal; wherein the first terminal may be a terminal in the roaming network.

It should be noted that, in a possible implementation manner of this embodiment, the first core network device includes an S-CSCF; the first core network device receives a first call request from the first terminal or the second terminal.

In another possible implementation of this embodiment, the first core network device includes an application server (AS); the first core network device receives a first call request from the first terminal or the second terminal.

In another possible implementation of this embodiment, the first core network device includes an AS; the first core network device receives a first call request from a third core network device, wherein the third core network device includes an S-CSCF.

The first call request includes a first value, wherein the first value is a value of a target parameter corresponding to the target service.

Optionally, the target business includes at least one of the following:

a) Voice call service;

b) Video call service.

Optionally, the target parameter includes at least one of the following:

a)GBR;

b) Maximum bit rate (MBR).

Optionally, the first value is a value of the GBR of the voice call service carried by the first terminal in the call request, for example, the first value is 512 kbps.

Step 302: When the first value does not match the second value, the first core network device performs any one of the following:

sending a second call request to a second terminal, where the second terminal is a call recipient corresponding to the first call request, The second call request includes the second value, wherein the second value is a value of the target parameter supported by the roaming network providing service for the first terminal.

Since the second value is the value of the target parameter of the target service supported by the roaming network providing services to the first terminal, the mismatch between the first value and the second value means that the values of the target parameters corresponding to the target service do not match, that is, the roaming network cannot successfully establish the target service for the first terminal.

Optionally, the second value is a value of the GBR of a voice call service supported by the roaming network providing services to the first terminal, for example, the second value is 64 kbps.

Optionally, the value of the target parameter of the target service supported by the roaming network may also be understood as the maximum value or minimum value that the roaming network can provide for the target parameter corresponding to the target service.

In this embodiment, when the first value does not match the second value, the first core network device sends a call response including the second value to the first terminal, wherein the call response message, such as a 488 message, is used to indicate the rejection of the first call request. Specifically, the 488 message means no acceptable here.

Specifically, in the case where the first core network device includes an S-CSCF, after determining that the first value does not match the second value, the first core network device sends a call response including the second value to the first terminal.

Alternatively, the first core network device sends a second call request including a second value to the second terminal.

Specifically, in the case where the first core network device includes an AS, after determining that the first value does not match the second value, the first core network device needs to modify the first value to the second value, and then send a second call request including the second value to the second terminal.

Optionally, the first value does not match the second value, including at least one of the following:

a) the first value is greater than the second value;

b) An absolute value of a difference between the first value and the second value is greater than a first threshold.

Optionally, sending a call response to the first terminal includes: the first core network device sends a 488 message to the first terminal, and the 488 message carries the second value.

Optionally, before the first core network device receives the first call request, it is necessary to determine whether the first terminal is in a roaming state, which specifically includes the following steps:

Step 1: The first core network device receives a registration request from a second core network device, where the registration request is initiated by the first terminal and includes a first public land mobile network identifier (PLMN ID), where the first PLMN ID is the PLMN ID of the roaming network.

Optionally, the terminal initiates an IMS registration request, which is routed to the second core network device, and the second core network device sends it to the first core network device.

Step 2: The first core network device determines first information based on the first PLMN ID; the first information includes at least one of the following:

a) indication information, used to indicate that the first terminal is in roaming state;

b) the first PLMN ID;

c) said second value.

It should be noted that the first core network device may determine whether the first terminal is in a roaming state by any of the following methods:

Mode 1: When the first core network device includes an S-CSCF and the second core network device includes a P-CSCF, the P-CSCF writes the first PLMN ID into the received registration request and sends it to the S-CSCF, and then the S-CSCF determines the first information based on the first PLMN ID in the registration request, and then determines whether the first terminal is in a roaming state. Since the registration request includes the first PLMN ID of the roaming network, the S-CSCF can obtain the first PLMN ID during the registration process, determine the first information based on the first PLMN ID, and determine whether the first terminal is in a roaming state based on the indication information in the first information.

Optionally, the S-CSCF determines that the first terminal is in roaming state based on the fact that the ID of the PLMN to which it belongs is different from the first PLMN ID included in the registration request message.

Method 2: When the first core network device includes AS and the second core network device includes S-CSCF, after the S-CSCF receives the registration request initiated by the first terminal, the S-CSCF sends the registration request to the AS, and then the AS determines the first information based on the first PLMN ID in the registration request, and then determines whether the first terminal is in a roaming state.

Since the registration request includes the first PLMN ID of the roaming network, the AS can obtain the first PLMN ID during the registration process, determine the first information based on the first PLMN ID, and determine whether the first terminal is in a roaming state based on the indication information in the first information.

Optionally, the AS determines that the first terminal is in roaming state based on the fact that the ID of the PLMN to which it belongs is different from the first PLMN ID included in the registration request message.

In the above implementation, during the registration process, the first core network device can determine whether the first terminal is in a roaming state based on the first information. When it is determined that the first terminal is in a roaming state, the first core network device determines whether the first value corresponding to the target service requested to be established matches the second value supported by the roaming network; when the first value does not match the second value, it indicates that the roaming network cannot successfully establish the target service for the first terminal; further, the first core network device sends a call response carrying the second value to the first terminal, so that the first terminal modifies the parameters corresponding to the target service based on the second value and then initiates a call request again; and/or the first core network device sends a second call request carrying the second value to the call recipient, so that the call recipient establishes the target service based on the second value, thereby successfully establishing a voice service for the user in the roaming area.

Optionally, the first core network device determines the first information based on the first PLMN ID, which can be specifically implemented in at least one of the following ways:

Method 1: The first core network device determines the second value based on a first mapping relationship and the first PLMN ID; the first mapping relationship is used to indicate the value of the target parameter respectively contracted by the home network of the first terminal and different roaming networks.

Specifically, in the first mapping relationship, the home public land mobile network (Home PLMN, HPLMN) of the first terminal has different contracts with different VPLMNs, that is, different VPLMNs correspond to different GBR values or MBR values.

For example, the first mapping relationship includes:

The GBR value of the voice call service subscribed by the HPLMN of the first terminal and PLMN-1 is 128 kbps;

The GBR value of the voice call service subscribed by the HPLMN of the first terminal and PLMN-2 is 64 kbps;

The GBR value of the voice call service subscribed by the HPLMN of the first terminal and PLMN-3 is 32 kbps;

At this time, the first core network device (such as S-CSCF or AS) is required to record which VPLMN the first terminal roams to, and obtain the value of the GBR or MBR signed by the HPLMN and the VPLMN based on the VPLMN ID.

Method 2: The first core network device determines the second value based on a second mapping relationship and the first PLMN ID; the second mapping relationship is used to indicate the value of the target parameter of the unified contract between the home network of the first terminal and at least one roaming network.

Specifically, in the second mapping relationship, the HPLMN of the first terminal has a unified contract with all VPLMNs, that is, as long as the first terminal is in any roaming network, the same GBR value or MBR value is used. At this time, the first core network device (such as S-CSCF or AS) only needs to record that the first terminal is in roaming state.

Method 3: The first core network device determines the second value based on configuration information and the first PLMN ID; the configuration information includes the second value corresponding to the first PLMN ID.

Method 4: The first core network device determines that the first terminal is in roaming state based on the first PLMN ID and the second PLMN ID, and the second PLMN ID is the PLMN ID of the home network of the first terminal.

In the above implementation, the first core network device can determine the indication information for indicating that the first terminal is in a roaming state, the first PLMN ID and the second value based on the first PLMN ID; based on the second value, the first terminal in the roaming network can successfully establish a target service with the second terminal, thereby improving the user experience.

Optionally, the first core network device determines whether the first value matches the second value, which can be specifically achieved through the following steps: when the first core network device receives the first call request, the first core network device obtains the second value based on the first information, and determines whether the first value matches the second value.

Specifically, in a possible implementation of this embodiment, the first core network device includes an S-CSCF; the S-CSCF saves the first information, and after the S-CSCF receives the first call request from the first terminal or the second terminal, obtains the second value based on the saved first information, and compares it with the first value in the first call request to determine whether the first value matches the second value.

In another possible implementation of this embodiment, the first core network device includes an AS; the AS saves the first information, and after the AS receives the first call request from the first terminal or the second terminal, obtains the second value based on the saved first information, and compares it with the first value in the first call request to determine whether the first value matches the second value.

In the above implementation, the first core network device saves the first information and then obtains the second value, and compares it with the first value in the first call request to determine whether the first value matches the second value; when the first value does not match the second value, the first core network device sends a call response carrying the second value to the first terminal, so that the first terminal modifies the parameters corresponding to the target service based on the second value and then initiates the call request again, thereby successfully establishing a voice service for the user in the roaming area; and/or the first core network device sends a second call request carrying the second value to the call recipient, so that the call recipient establishes the target service based on the second value, thereby successfully establishing a voice service for the user in the roaming area, thereby improving the user experience.

Optionally, when the first core network device includes an AS and the third core network device includes an S-CSCF, the first core network device receives the first call request, which is specifically implemented by the following steps:

The first core network device receives the first call request from the third core network device; the first call request also includes second information; the second information includes at least one of the following:

b) the first PLMN ID;

c) said second value.

Specifically, when the S-CSCF receives a first call request from the first terminal or the second terminal, the S-CSCF sends the first call request to the AS, wherein the first call request also includes the second information.

The AS obtains a second value (for example, the value of the GBR parameter) supported by the voice service of the roaming network based on the second information. When the AS determines that the second value does not match the GBR parameter included in the first call request, the AS modifies the value of the GBR parameter in the first call request to the second value, and then sends a second call request to the second terminal, wherein the second call request includes the second value.

Optionally, the second information is determined specifically through the following steps: the first core network device determines the second information based on the first call request.

In the above implementation, when the first value does not match the second value, the first core network device modifies the first value in the first call request to the second value, and then sends the second call request to the second terminal, so that the first terminal in the roaming network can successfully establish the target service with the second terminal based on the second value, thereby improving the user experience.

FIG. 4 is a second flow chart of a calling method provided in an embodiment of the present application. As shown in FIG. 4 , the method includes step 401; wherein:

Step 401: The third core network device sends a first call request to the first core network device; the first call request is used to establish a target service for the first terminal, and the first call request includes a first value, which is the value of a target parameter corresponding to the target service; the first call request also includes second information; the second information includes at least one of the following:

a first PLMN ID, wherein the first PLMN ID is a PLMN ID of a roaming network;

First of all, it should be noted that the embodiment of the present application can be applied to the scenario where the two communicating parties make a call; the core network device Including but not limited to the types of network side devices 12 listed above, this application is not limited to this.

For the convenience of description, the following takes the voice communication service as an example for introduction.

When the terminal is in a roaming network, the terminal cannot make or receive voice calls because the parameters supported by the home network and the roaming network are inconsistent.

Therefore, in order to enable the communicating parties to successfully establish voice communication, in this embodiment, the third core network device sends a first call request including a first value to the first core network device.

Optionally, the first core network device includes AS; the third core network device includes S-CSCF.

Specifically, the S-CSCF sends a first call request to the AS, wherein the first call request includes the first value and the second information.

Accordingly, after receiving the first call request from the S-CSCF, the AS first determines whether the first terminal is in a roaming state based on the indication information. If the first terminal is in a roaming state and the first value does not match the second value, the AS modifies the value of the first value in the first call request to the second value, and then sends a second call request to the second terminal, wherein the second call request includes the second value.

Optionally, the target parameter includes at least one of the following: GBR; MBR.

Optionally, the target service includes at least one of the following: a voice call service; or a video call service.

In the above implementation, the third core network device sends a first call request to the first core network device to establish a target service for the first terminal, the first call request includes a first value and second information, and the second information includes the second value; accordingly, after the first core network device receives the first call request to establish a target service for the first terminal, if the first value corresponding to the target service requested to be established does not match the second value supported by the roaming network, the first core network device sends a second call request carrying the second value to the call recipient, so that the call recipient establishes the target service based on the second value, thereby successfully establishing a voice service for the user in the roaming area, thereby improving the user experience.

Optionally, before the third core network device sends the first call request to the first core network device, it is necessary to determine whether the first terminal is in a roaming state, which specifically includes the following steps:

Step 1: The third core network device receives a registration request from a fourth core network device, where the registration request is initiated by the first terminal and includes the first PLMN ID;

Step 2: The third core network device determines first information based on the first PLMN ID; the first information includes at least one of the following:

b) the first PLMN ID;

c) said second value.

Optionally, the fourth core network device includes a P-CSCF.

For example, the S-CSCF receives a registration request from the P-CSCF, which includes a first PLMN ID; then the S-CSCF determines the first information based on the first PLMN ID.

Optionally, the third core network device determines the first information based on the first PLMN ID, specifically by any of the following methods:

Method 1: The third core network device determines the second value based on the first mapping relationship and the first PLMN ID; the first mapping relationship is used to indicate the value of the target parameter respectively contracted by the home network of the first terminal and different roaming networks.

Method 2: The third core network device determines the second value based on a second mapping relationship and the first PLMN ID; the second mapping relationship is used to indicate the value of the target parameter of the unified contract between the home network of the first terminal and at least one roaming network.

Mode 3: The third core network device determines the second value based on configuration information and the first PLMN ID; the configuration information includes the second value corresponding to the first PLMN ID;

Method 4: The third core network device determines that the first terminal is in roaming state based on the first PLMN ID and the second PLMN ID, and the second PLMN ID is the PLMN ID of the home network of the first terminal.

Optionally, the third core network device determines whether the first value matches the second value, which is specifically implemented by the following steps:

Step 1: The third core network device saves the first information;

Step 2: When the third core network device receives the first call request, the third core network device obtains the second value based on the saved first information and determines whether the first value matches the second value.

For example, after determining the first information based on the first PLMN ID, the S-CSCF saves the first information; when the S-CSCF receives the first call request, it obtains the second value based on the saved first information and determines whether the first value matches the second value.

Referring to FIG. 5 , FIG. 5 is a schematic diagram of a process in which UE-1 initiates a registration request according to an embodiment of the present application. The specific steps are as follows:

Step 1: UE-1 sends an IMS registration request message.

Step 2: P-CSCF subscribes to the Home Policy Control Function (H-PCF) of UE-1 for changes in the PLMN that provides services for UE-1.

Step 3: The H-PCF sends a notification message to the P-CSCF. The notification message carries the ID of the PLMN (VPLMN) currently providing service for UE-1.

Step 4: P-CSCF sends a registration request message to S-CSCF, which carries the VPLMN ID.

Step 5: S-CSCF records the first information.

Specifically, the first information includes at least one of the following: indication information, used to indicate that UE-1 is in roaming state; VPLMN ID; the value of the first value (for example, GBR parameter) that can be used for the voice service corresponding to the VPLMN.

Among them, the value of the GBR parameter is obtained and saved by the S-CSCF based on the VPLMN ID.

Step 6. Complete the registration process.

Referring to FIG. 6 , FIG. 6 is a schematic diagram of a process of establishing a voice bearer between UE-1 and UE-2 provided in an embodiment of the present application, and the specific steps are as follows:

Step 1: S-CSCF receives an invite request sent by UE-1 or UE-2, where the invite request carries a first value (eg, a GBR parameter) corresponding to the voice service requested by UE-1 or UE-2.

For example, a voice bearer with a GBR of 512 kbps is requested to be established through b=AS:512.

Step 2: The S-CSCF obtains a second value (eg, a GBR parameter available for the voice service of the PLMN providing services for UE-1) according to the recorded first information.

The way in which the S-CSCF records the first information is shown in FIG5 .

Step 3: If the value of the GBR information does not match the value of the GBR carried by UE-1 in the invite message, the S-CSCF sends a 488 message to UE-1, which includes the GBR parameters that can be used by the VPLMN.

It should be noted that mismatch can be understood as the first value being greater than the second value, or the absolute value of the difference between the first value and the second value being greater than a preset value, or the first value being greater than the second value and the absolute value of the difference between the first value and the second value being greater than a preset value.

After the S-CSCF sends the 488 message to UE- 1 , UE- 1 re-initiates the invite message using the second message contained in the 488 .

It is understandable that, here, UE-1 is used as an example for explanation, and UE-2 can also be the calling user. That is, in FIG6 , UE-2 initiates a call to UE-1. At this time, after the S-CSCF receives the invite request from UE-2, the S-CSCF sends a 488 message to UE-2.

In a possible implementation of this embodiment, the HPLMN of UE-1 has different contracts with different VPLMNs, that is, the GBR has different values. In this case, the S-CSCF needs to record which VPLMN the UE-1 roams to, and obtain the GBR value of the HPLMN contract with the VPLMN based on the VPLMN ID.

In another possible implementation of this embodiment, the HPLMN of UE-1 has a unified contract with all VPLMNs, that is, as long as UE-1 is in the VPLMN network, the value of the GBR is used. In this case, the S-CSCF only needs to record that the UE is in roaming state.

The S-CSCF may obtain the value of the GBR that can be used by the VPLMN locally or from other network elements.

Referring to FIG. 7 , FIG. 7 is a second schematic diagram of a process in which UE-1 initiates a registration request according to an embodiment of the present application, and the specific steps are as follows:

Step 1: UE-1 sends an IMS registration request message.

Step 2: The P-CSCF subscribes to the H-PCF of UE-1 for the change of the PLMN serving UE-1.

Step 5. S-CSCS sends a registration request message to AS, which carries the VPLMN ID.

Step 6: The AS records the first information.

The base first information may be information indicating that UE-1 is in roaming state, or VPLMN ID, or the value of a GBR parameter that can be used for the voice service corresponding to the VPLMN.

It should be noted that the value of the GBR parameter is obtained and saved by the AS based on the VPLMN ID.

Step 7. Complete the registration process.

Referring to FIG. 8 , FIG. 8 is a second schematic diagram of a process of establishing a voice bearer between UE-1 and UE-2 provided in an embodiment of the present application. Specific steps are as follows:

Step 2: The S-CSCF sends the invite request to the AS providing service for UE-1.

Step 3: The AS obtains a second value (ie, a GBR parameter available for the voice service of the VPLMN providing services for UE-1) according to the recorded first information, wherein the manner in which the AS records the first information is shown in FIG. 7 .

Step 4: If the GBR value does not match the GBR value carried by UE-1 in the invite message, the AS modifies the GBR parameter of the invite message to a parameter usable by the VPLMN and sends it to the S-CSCF; for example, it is modified to b=AS:64.

It should be noted that mismatch can be understood as the first value being smaller than the second value, or the absolute value of the difference between the first value and the second value being greater than a preset value, or the first value being smaller than the second value and the absolute value of the difference between the first value and the second value being greater than a preset value.

Step 5: S-CSCF sends the modified invite request to UE-2.

Step 6-9: UE-2 carries the description information of the voice received by the other end through a response message, such as 200OK.

It should be noted that UE-1 is used as the calling user here for explanation, UE-2 can also be the calling user, that is, UE-2 initiates a call to UE-1 in Figure 8, and when AS receives the invite sent by UE-2, it can also modify the parameters.

Referring to FIG. 9 , FIG. 9 is a third schematic diagram of a process of establishing a voice bearer between UE-1 and UE-2 provided in an embodiment of the present application, and the specific steps are as follows:

First, it should be noted that the process of UE-1 initiating a registration request in this embodiment is the same as that in FIG. 7 , and will not be described in detail here.

Step 2: S-CSCF sends the invite request to the AS providing service for UE-1. The invite request carries second information, which may be information indicating that UE-1 is in roaming state, or VPLMN ID, or the value of a GBR parameter that can be used for the voice service corresponding to the VPLMN.

Step 3: The AS obtains a second value (ie, a GBR parameter available for the voice service of the VPLMN providing services for UE-1) according to the second information.

Step 4: If the value of the GBR parameter does not match the value of the GBR parameter carried by UE-1 in the invite message, the AS modifies the GBR parameter of the invite message to a parameter that can be used by the VPLMN and sends it to the S-CSCF; for example, modify it to b=AS:64

Mismatch can be understood as the first value being greater than the second value, or the absolute value of the difference between the first value and the second value being greater than a preset value, or the first value being greater than the second value and the absolute value of the difference between the first value and the second value being greater than a preset value.

Step 5-9: S-CSCF sends the modified invite request to UE-2. UE-2 sends a response message, such as 200OK, carrying the description information of the voice received by the other end.

It should be noted that UE-1 is used as the calling user here for explanation, UE-2 can also be the calling user, that is, UE-2 initiates a call to UE-1 in Figure 9, and when AS receives the invite sent by UE-2, it can also modify the parameters.

The calling method provided in the embodiment of the present application can be executed by a calling device. Taking the calling method executed by the device as an example, the calling device provided by the embodiment of the present application is described.

FIG. 10 is one of the structural diagrams of a calling device provided in an embodiment of the present application. As shown in FIG. 10 , the calling device 1000 is applied to a first core network device, including:

The first receiving module 1001 is used to receive a first call request, where the first call request is used to request to establish a target service for a first terminal, and the first call request includes a first value, where the first value is a value of a target parameter corresponding to the target service;

The first sending module 1002 is configured to, when the first value does not match the second value, perform any of the following:

In the calling device provided in the embodiment of the present application, after receiving a first call request for establishing a target service for a first terminal, when a first value corresponding to the target service requested to be established does not match a second value supported by the roaming network, the first core network device sends a call response carrying the second value to the first terminal, so that the first terminal modifies the parameters corresponding to the target service based on the second value and then initiates the call request again, thereby successfully establishing a voice service for the user in the roaming area; and/or the first core network device sends a second call request carrying the second value to the call recipient, so that the call recipient establishes the target service based on the second value, thereby successfully establishing a voice service for the user in the roaming area, thereby improving the user experience.

The first value is greater than the second value;

An absolute value of a difference between the first value and the second value is greater than a first threshold.

Optionally, the device further comprises:

A second receiving module is configured to receive a registration request from a second core network device, wherein the registration request is initiated by the first terminal, and the registration request includes a first public land mobile network identifier PLMN ID, and the first PLMN ID is the PLMN ID of the roaming network;

A first determining module is configured to determine first information based on the first PLMN ID; the first information includes at least one of the following:

the first PLMN ID;

the second value.

Optionally, the first determining module is further configured to perform at least one of the following:

Based on the first mapping relationship and the first PLMN ID, determining the second value; the first mapping relationship is used to indicate the value of the target parameter respectively signed by the home network of the first terminal and different roaming networks;

Based on the second mapping relationship and the first PLMN ID, the second value is determined; the second mapping relationship is used to indicate indicating a value of the target parameter uniformly signed by the home network of the first terminal and at least one roaming network;

Determine the second value based on configuration information and the first PLMN ID; the configuration information includes the second value corresponding to the first PLMN ID;

Based on the first PLMN ID and the second PLMN ID, it is determined that the first terminal is in roaming state, and the second PLMN ID is the PLMN ID of the home network of the first terminal.

Optionally, the device further comprises:

The first judgment module is used to obtain the second value according to the first information and judge whether the first value matches the second value when the first core network device receives the first call request.

Optionally, the first core network device includes a service call session control function, and the second core network device includes a proxy call session control function;

Alternatively, the first core network device includes an application server, and the second core network device includes a service call session control function.

Optionally, the first receiving module 1001 is further configured to:

The first call request is received from a third core network device; the first call request also includes second information; the second information includes at least one of the following:

the first PLMN ID;

the second value.

Optionally, the device further comprises:

The second determination module is used for the first core network device to determine the second information based on the first call request.

Optionally, the first core network device includes an application server; and the third core network device includes a service call session control function.

Optionally, the first sending module 1002 is further configured to:

Send a 488 message to the first terminal, where the 488 message carries the second value.

Optionally, the target parameter includes at least one of the following: a guaranteed bit rate GBR; a maximum bit rate MBR.

FIG. 11 is a second structural diagram of a calling device provided in an embodiment of the present application. As shown in FIG. 11 , the calling device 1100 is applied to a third core network device, including:

The second sending module 1101 is used to send a first call request to the first core network device; the first call request is used to establish a target service for the first terminal, the first call request includes a first value, and the first value is the value of a target parameter corresponding to the target service; the first call request also includes second information; the second information includes at least one of the following:

The second value is the target service supported by the roaming network providing service for the first terminal. The value of the corresponding target parameter.

In the calling device provided in the embodiment of the present application, a first call request for establishing a target service for a first terminal is sent to a first core network device, the first call request includes a first value and second information, and the second information includes the second value; accordingly, after the first core network device receives the first call request for establishing a target service for the first terminal, if the first value corresponding to the target service requested to be established does not match the second value supported by the roaming network, the first core network device sends a second call request carrying the second value to the call recipient, so that the call recipient establishes the target service based on the second value, thereby successfully establishing a voice service for the user in the roaming area, thereby improving the user experience.

Optionally, the device further comprises:

A third receiving module is configured to receive a registration request from a fourth core network device, wherein the registration request is initiated by the first terminal and includes the first PLMN ID;

The third determination module is configured to determine first information based on the first PLMN ID; the first information includes at least one of the following:

the first PLMN ID;

the second value.

Optionally, the third determination module is further configured to perform at least one of the following:

Based on a second mapping relationship and the first PLMN ID, determining the second value; the second mapping relationship is used to indicate the value of the target parameter of the unified contract between the home network of the first terminal and at least one roaming network;

Optionally, the device further comprises:

The second judgment module is used to obtain the second value according to the first information and judge whether the first value matches the second value when the third core network device receives the first call request.

Optionally, the fourth core network device includes a proxy call session control function.

The calling device in the embodiment of the present application may be an electronic device, such as an electronic device with an operating system, or a component in an electronic device, such as an integrated circuit or a chip. The electronic device may be a terminal, or may be other devices other than a terminal. For example, the terminal may include but is not limited to the types of terminal 11 listed above, and other devices may include but are not limited to the types of terminal 11 listed above. It may be a server, a network attached storage (NAS), etc., and is not specifically limited in the embodiments of the present application.

The calling device provided in the embodiment of the present application can implement the various processes implemented in the method embodiments of Figures 3 to 9 and achieve the same technical effect. To avoid repetition, it will not be repeated here.

FIG12 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application. As shown in FIG12, the communication device 1200 includes a processor 1201 and a memory 1202. The memory 1202 stores a program or instruction that can be run on the processor 1201. For example, when the communication device 1200 is a first core network device, the program or instruction is executed by the processor 1201 to implement the various steps of the above-mentioned call method embodiment shown in FIG3, and can achieve the same technical effect. When the communication device 1200 is a third core network device, the program or instruction is executed by the processor 1201 to implement the various steps of the above-mentioned call method embodiment shown in FIG4, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

Optionally, Figure 13 is a schematic diagram of the structure of a core network device provided in an embodiment of the present application. As shown in Figure 13, the core network device 1300 includes: a processor 1301, a network interface 1302 and a memory 1303. Among them, the network interface 1302 is, for example, a common public radio interface (CPRI).

Specifically, the core network device 1300 of the embodiment of the present invention further includes: instructions or programs stored in the memory 1303 and executable on the processor 1301. For example, when the core network device 1300 is the first core network device, the processor 1301 calls the instructions or programs in the memory 1303 to implement the various steps of the calling method embodiment shown in FIG. 3, and can achieve the same technical effect. When the core network device 1300 is the third core network device, the processor 1001 calls the instructions or programs in the memory 1003 to implement the various steps of the calling method embodiment shown in FIG. 4, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

An embodiment of the present application also provides a calling system, including: a first terminal, a second terminal, a first core network device and a third core network device, wherein the first core network device can be used to execute the steps of the calling method described in Figure 3 above, and the third core network device can be used to execute the steps of the calling method described in Figure 4 above.

An embodiment of the present application also provides a readable storage medium, which may be volatile or non-volatile, and stores a program or instruction. When the program or instruction is executed by a processor, the various processes of the above-mentioned calling method embodiment are implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

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

An embodiment of the present application further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned calling method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

The present application also provides a computer program/program product, wherein the computer program/program product is stored in In the storage medium, the computer program/program product is executed by at least one processor to implement the various processes of the above-mentioned calling method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM/RAM, a magnetic disk, or an optical disk), and includes a number of instructions for enabling a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

A calling method, comprising:

The first core network device receives a first call request, where the first call request is used to request to establish a target service for the first terminal, and the first call request includes a first value, where the first value is a value of a target parameter corresponding to the target service;

When the first value does not match the second value, the first core network device performs any one of the following:

Sending a call response to the first terminal, where the call response includes the second value;

Sending a second call request to a second terminal, where the second terminal is a call recipient corresponding to the first call request, and the second call request includes the second value;

The second value is a value of a target parameter corresponding to the target service supported by the roaming network providing service to the first terminal.
The calling method according to claim 1, wherein the first value does not match the second value, including at least one of the following:

The first value is greater than the second value;

An absolute value of a difference between the first value and the second value is greater than a first threshold.
The calling method according to claim 1 or 2, wherein the method further comprises:

The first core network device receives a registration request from the second core network device, the registration request is initiated by the first terminal, the registration request includes a first public land mobile network identifier PLMN ID, and the first PLMN ID is the PLMN ID of the roaming network;

The first core network device determines first information based on the first PLMN ID; the first information includes at least one of the following:

Indication information, used to indicate that the first terminal is in roaming state;

the first PLMN ID;

the second value.
The calling method according to claim 3, wherein the first core network device determines the first information based on the first PLMN ID, including at least one of the following:

The first core network device determines the second value based on the first mapping relationship and the first PLMN ID; the first mapping relationship is used to indicate the value of the target parameter respectively signed by the home network of the first terminal and different roaming networks;

The first core network device determines the second value based on the second mapping relationship and the first PLMN ID; the second mapping relationship is used to indicate the value of the target parameter uniformly signed by the home network of the first terminal and at least one roaming network;

The first core network device determines the second value based on configuration information and the first PLMN ID; the configuration information includes the second value corresponding to the first PLMN ID;

The first core network device determines, based on the first PLMN ID and the second PLMN ID, that the first terminal is in Roaming state, the second PLMN ID is the PLMN ID of the home network of the first terminal.
The calling method according to claim 3 or 4, wherein the method further comprises:

When the first core network device receives the first call request, the first core network device obtains the second value according to the first information, and determines whether the first value matches the second value.
The calling method according to claim 3, wherein the first core network device includes a service call session control function, and the second core network device includes a proxy call session control function;

Alternatively, the first core network device includes an application server, and the second core network device includes a service call session control function.
The calling method according to claim 1 or 2, wherein the first core network device receives the first call request, comprising:

The first core network device receives the first call request from the third core network device; the first call request also includes second information; the second information includes at least one of the following:

Indication information, used to indicate that the first terminal is in roaming state;

the first PLMN ID;

the second value.
The calling method according to claim 7, wherein the method further comprises:

The first core network device determines the second information based on the first call request.
The calling method according to claim 7, wherein the first core network device includes an application server; and the third core network device includes a service call session control function.
The calling method according to claim 1, wherein the sending a call response to the first terminal comprises:

The first core network device sends a 488 message to the first terminal, and the 488 message carries the second value.
The calling method according to any one of claims 1 to 10, wherein the target parameter includes at least one of the following: a guaranteed bit rate (GBR); a maximum bit rate (MBR).
The calling method according to any one of claims 1 to 10, wherein the target service includes at least one of the following: a voice call service; a video call service.
A calling method, comprising:

The third core network device sends a first call request to the first core network device; the first call request is used to establish a target service for the first terminal, the first call request includes a first value, and the first value is the value of a target parameter corresponding to the target service; the first call request also includes second information; the second information includes at least one of the following:

Indication information, used to indicate that the first terminal is in roaming state;

A first public land mobile network identifier PLMN ID, wherein the first PLMN ID is a PLMN ID of a roaming location network;

The second value is a value of a target parameter corresponding to the target service supported by a roaming network providing services to the first terminal.
The calling method according to claim 13, wherein the method further comprises:

The third core network device receives a registration request from a fourth core network device, the registration request being received by the first The terminal initiates the registration request, wherein the registration request includes the first PLMN ID;

The third core network device determines first information based on the first PLMN ID; the first information includes at least one of the following:

Indication information, used to indicate that the first terminal is in roaming state;

the first PLMN ID;

the second value.
The calling method according to claim 14, wherein the third core network device determines the first information based on the first PLMN ID, including at least one of the following:

The third core network device determines the second value based on the first mapping relationship and the first PLMN ID; the first mapping relationship is used to indicate the value of the target parameter respectively signed by the home network of the first terminal and different roaming networks;

The third core network device determines the second value based on the second mapping relationship and the first PLMN ID; the second mapping relationship is used to indicate the value of the target parameter uniformly signed by the home network of the first terminal and at least one roaming network;

The third core network device determines the second value based on configuration information and the first PLMN ID; the configuration information includes the second value corresponding to the first PLMN ID;

The third core network device determines that the first terminal is in roaming state based on the first PLMN ID and the second PLMN ID, and the second PLMN ID is the PLMN ID of the home network of the first terminal.
The calling method according to claim 14 or 15, wherein the method further comprises:

When the third core network device receives the first call request, the third core network device obtains the second value according to the first information, and determines whether the first value matches the second value.
According to any one of claims 13 to 15, the first core network device includes an application server; and the third core network device includes a service call session control function.
The calling method according to claim 14, wherein the fourth core network device includes a proxy call session control function.
The calling method according to any one of claims 13 to 18, wherein the target parameter includes at least one of the following: a guaranteed bit rate (GBR); a maximum bit rate (MBR).
The calling method according to any one of claims 13 to 19, wherein the target service includes at least one of the following: a voice call service; a video call service.
A calling device, comprising:

A first receiving module, configured to receive a first call request, wherein the first call request is used to request to establish a target service for a first terminal, wherein the first call request includes a first value, and the first value is a value of a target parameter corresponding to the target service;

A first sending module is configured to, when the first value does not match the second value, perform any of the following:

Sending a call response to the first terminal, where the call response includes the second value;

Sending a second call request to a second terminal, where the second terminal is a call recipient corresponding to the first call request, and the second call request includes the second value;

The second value is a value of a target parameter corresponding to the target service supported by the roaming network providing service to the first terminal.
A calling device, comprising:

The second sending module is used to send a first call request to the first core network device; the first call request is used to establish a target service for the first terminal, the first call request includes a first value, and the first value is the value of a target parameter corresponding to the target service; the first call request also includes second information; the second information includes at least one of the following:

Indication information, used to indicate that the first terminal is in roaming state;

A first public land mobile network identifier PLMN ID, wherein the first PLMN ID is a PLMN ID of a roaming location network;

The second value is a value of a target parameter corresponding to the target service supported by a roaming network providing services to the first terminal.
A first core network device, comprising a processor and a memory, wherein the memory stores programs or instructions that can be run on the processor, and when the program or instructions are executed by the processor, the steps of the calling method as described in any one of claims 1 to 12 are implemented.
A third core network device, comprising a processor and a memory, wherein the memory stores programs or instructions that can be run on the processor, and when the program or instructions are executed by the processor, the steps of the calling method as described in any one of claims 13 to 20 are implemented.
A readable storage medium, wherein the readable storage medium stores a program or instruction, and when the program or instruction is executed by a processor, it implements the calling method as described in any one of claims 1 to 12, or implements the steps of the calling method as described in any one of claims 13 to 20.