CN116801331A

CN116801331A - Method, device and terminal for realizing voice service

Info

Publication number: CN116801331A
Application number: CN202210260559.2A
Authority: CN
Inventors: 康艳超
Original assignee: Vivo Mobile Communication Co Ltd
Current assignee: Vivo Mobile Communication Co Ltd
Priority date: 2022-03-16
Filing date: 2022-03-16
Publication date: 2023-09-22
Also published as: WO2023174321A1

Abstract

The application discloses a method, a device and a terminal for realizing voice service, belonging to the field of wireless communication, wherein the method for realizing voice service comprises the following steps: after a first non-Access Stratum (Non Access Stratum, NAS) of a terminal residing in a first network acquires a first target indication, sending a second target indication to a first Access Stratum (AS) of the terminal, where the second target indication includes one of: an indication to fall back to the second network, an indication to redirect to the second network, the first NAS of the terminal corresponding to the first network; triggering a first AS of the terminal to perform network reselection to a second network, wherein the first AS of the terminal corresponds to the first network; and the terminal executes voice service through the second network.

Description

Method, device and terminal for realizing voice service

Technical Field

The application belongs to the technical field of wireless communication, and particularly relates to a method, a device and a terminal for realizing voice service.

Background

After commercial deployment of a fifth generation (5G) network, there may be a scenario in which a fourth generation (fourth generation, 4G) Voice over LTE (VoLTE) service is used to accommodate a calling and called Voice service initiated by a 5G terminal. For example, in early business of 5G networks, some operators might not directly deploy 5G voice services, but use 4G VoLTE services to maximize the role of existing network resources; or, the 5G network has small high-frequency coverage, and a certain number of areas are not covered by the 5G NR network, so that the 4G LTE coverage is also needed to be used for continuing the voice service; alternatively, the capacity of the 5G network is limited, and when the load of the 5G network is high, the operator also wants to transfer the 5G voice service of the user to the 4G network to trigger and execute.

In the above scenario, there is a need for a terminal to initially register with a first network (e.g., a 5G network) and perform related data services, but to fall back into a second network (e.g., a 4G network) to trigger and perform voice services when the voice services (including a caller or a callee) need to be performed. To address this need, a quick and efficient solution is currently being provided.

Disclosure of Invention

The embodiment of the application provides a method, a device and a terminal for realizing voice service, which can solve the problem of how to quickly fall back to a second network to execute voice service when the terminal residing in a first network.

In a first aspect, a method for implementing a voice service is provided, including: after a first non-Access Stratum (Non Access Stratum, NAS) of a terminal residing in a first network acquires a first target indication, sending a second target indication to a first Access Stratum (AS) of the terminal, where the second target indication includes one of: an indication to fall back to the second network, an indication to redirect to the second network, the first NAS of the terminal corresponding to the first network; triggering a first AS of the terminal to perform network reselection to a second network, wherein the first AS of the terminal corresponds to the first network; and the terminal executes voice service through the second network.

In a second aspect, a device for implementing a voice service is provided, where the device is applied to a terminal, and the device includes: the acquiring module is configured to send a second target indication to a first access stratum AS of a terminal residing in a first network after acquiring the first target indication through a first NAS of the terminal, where the second target indication includes one of: an indication to fall back to the second network, an indication to redirect to the second network, the first NAS of the terminal corresponding to the first network; and the triggering module is used for triggering the network to be reselected to a second network through a first AS of the terminal, wherein the first AS of the terminal corresponds to the first network.

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, comprising a processor and a communication interface, wherein the processor is configured to implement the steps of the method according to the first aspect, and the communication interface is configured to communicate with an external device.

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 implementing the steps of the method according to 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, after the first NAS of the terminal residing in the first network acquires the first target instruction, the first AS of the terminal sends the instruction of falling back to the second network or the instruction of redirecting to the second network, the first AS triggers the network to reselect to the second network according to the received instruction, and then the terminal executes the voice service through the second network, so that the terminal residing in the first network can quickly fall back to the second network to execute the voice service, and if the terminal is in an idle state, the terminal does not need to enter a connection state in the first network and fall back to the second network, but directly performs network reselection, thereby shortening the time delay of the voice service.

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 schematic flow diagram illustrating a process of implementing voice service by a terminal initially registered in a 5G network falling back to a 4G network;

fig. 3 is a schematic flow chart of a method for implementing a voice service according to an embodiment of the present application;

fig. 4 is a flow chart illustrating a method for implementing a calling voice service in an embodiment of the present application;

fig. 5 is a schematic flow chart of a method for implementing a called voice service according to an embodiment of the present application;

fig. 6 shows a schematic structural diagram of a device for implementing a voice service according to an embodiment of the present application;

fig. 7 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 8 shows a schematic hardware structure of a terminal according to an embodiment of the present application.

Detailed Description

The technical solutions of 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, which are derived by a person skilled in the art based on the embodiments of the application, fall within the scope of protection of the application.

The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements 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 "first" and "second" distinguishing between objects generally are not limited in number to the extent that the first object may, for example, 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 should be noted that the embodiments of the application are describedThe technology of (a) is not limited to long term evolution (Long Term Evolution, LTE)/evolution of LTE (LTE-Advanced, LTE-a) systems, but can 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 application are often used interchangeably, and the techniques described 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 an embodiment of the present application is 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.. 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 comprise an access network device and/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, 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 transmitting/receiving point (TransmittingReceivingPoint, TRP), or some other suitable terminology in the art, a WLAN access point, a WiFi node, etc., and 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 embodiment 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: a core network node, a core network function, a mobility management entity (Mobility Management Entity, MME), an access mobility management function (Access and Mobility Management Function, AMF), a session management function (Session Management Function, SMF), a user plane function (User Plane Function, UPF), a policy control function (Policy Control Function, PCF), a policy and charging rules function (Policy and Charging Rules Function, PCRF), an edge application service discovery function (EdgeApplicationServerDiscoveryFunction, EASDF), unified data management (Unified Data Management, UDM), unified data repository (Unified Data Repository, UDR), a home subscriber server (Home Subscriber Server, HSS), a centralized network configuration (Centralized network configuration, CNC), a network storage function (Network Repository Function, NRF), a network opening function (NetworkExposureFunction, NEF), a local NEF (LocalNEF, or L-NEF), a binding support function (Binding Support Function, BSF), an application function (Application Function, AF), and the like. It should be noted that, 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.

For the requirement that a terminal present in some scenarios initially registers with the 5G network and performs related data services, but can fall back into the 4G network to trigger and perform voice services when it is required to perform voice services (including calling or called), fig. 2 shows a possible solution with which a 5G UE can quickly fall back to 4G and perform VoLTE when it initiates the calling or called voice services. As shown in fig. 2, the solution mainly comprises the following steps:

s201, after the UE registers in 5G, if a calling or called voice service is initiated, a voice service establishment request signaling (IMS SIP signaling) triggers a 5G core network (5G Core Network,5GC) network to establish a 5G QoS identifier (5G QoS Identifier,5QI) =1 QoS flow (flow).

S202, a 5GC Network Function (NF) initiates a QoS flow suggestion request to the NG RAN for requesting to establish a 5 qi=1 QoS flow corresponding air interface tunnel and an N3 tunnel.

S203, the NG RAN receives the QoS flow suggestion request (5qi=1) and triggers a UE handover or redirection procedure for handover or redirection of the UE to the 4G LTE cell.

S204, NG RAN interacts with the core network, refuses to modify the protocol data unit (Protocol Data Unit, PDU) session indication, and performs the multimedia subsystem (IP Multimedia Subsystem, IMS) voice fallback procedure.

S205, UE switches or redirects to the 4G LTE cell. After the UE accesses the 4G LTE cell, S206a is executed in case of N26 interface deployment, and S206b is executed in case of no N26 interface deployment.

S206a, a tracking area update (Tracking Area update, TAU) procedure performed by the UE, for registration or location update in the 4G network.

S206b, the UE performs attachment (attach) and concurrently establishes a handover attachment (handover attach) type PDN connection procedure.

After the TAU procedure or the attach procedure is finished, the UE re-establishes an IMS packet data network (Packet Data Network, PDN) connection at the 4G network, which is used to transport the UE and IMS network direct signaling.

S207, the evolved packet core network (Evolved Packet Core, EPC) network triggers qci=1 bearer establishment in the 4G network according to IMS signaling, the bearer being used for transmitting VoLTE service user plane data.

S208, the VoLTE calling and called party is established, and normal conversation can be achieved.

For the UE which is in an idle state originally, such as a calling party initiates a 5G voice service, based on the solution, the UE needs to initiate a 5G service request (service request) process to enter a 5G connection state firstly, and then triggers the process steps; for the UE that is in the idle state, for example, as the called party of the voice service, based on the above mechanism, the 5G network needs to page the UE in the 5G cell first, so that it enters the connected state, and then triggers the above procedure steps. It can be seen that, for the UE in idle state, with the above solution, no matter the UE is the calling party or the called party of the voice service, the UE needs to enter the 5G network connection state first, and then enter the 4G through network switching or other modes. This makes the continuous delay for the idle state UE to initiate the 5G voice service long, and the user experience is poor.

The implementation scheme of the voice service provided by the embodiment of the application is described in detail below through some embodiments and application scenes thereof with reference to the accompanying drawings.

Fig. 3 shows a schematic flow diagram of a transmission method in an embodiment of the application, and the method 300 may be performed by a terminal. In other words, the method may be performed by software or hardware installed on the terminal. As shown in fig. 3, the method may include the following steps.

S310, after a first NAS of a terminal residing in a first network acquires a first target instruction, sending a second target instruction to a first AS of the terminal, wherein the second target instruction comprises one of the following components: an indication to fall back to the second network, an indication to redirect to the second network.

In the embodiment of the present application, the terminal residing in the first network may be in an idle state or a connected state, which is not limited in the embodiment of the present application. The radio access technologies employed by the first network and the second network are different.

In an embodiment of the present application, the first network includes, but is not limited to, a 5G network, and the second network includes, but is not limited to, an evolved packet system (Evolved Packet System, EPS) network, which may also be referred to as a 4G network or an LTE network.

In the embodiment of the present application, the first NAS of the terminal is a NAS corresponding to the first network in the terminal, for example, a 5G NAS of the terminal, i.e., a UE 5G NAS, and further may be a 5GMM or a 5GSM, and the first AS of the terminal is an AS corresponding to the first network in the terminal, for example, a 5G AS of the terminal, i.e., a UE 5G AS.

In one possible implementation manner of the embodiment of the present application, the first NAS of the terminal obtaining the first target indication may obtain, for the first NAS of the terminal, a first indication from an upper layer of the terminal, where the first indication includes, but is not limited to, one of the following:

(1) A multimedia telephony service (Multimedia telephone, MMTel) voice call indication;

(2) MMTel voice call start indication;

(3) MMTel video call indication;

(4) MMTel video call start indication;

(5) An indication of signaling related to IMS registration of an uplink IP multimedia subsystem;

(6) An uplink IMS registration related signaling start instruction;

(7) An IP-based short message SMSoIP indication;

(8) SMSoIP start indication.

That is, in the possible implementation manner, after acquiring the first instruction from the upper layer, the first NAS determines to fall back to the second network, and sends the second target instruction to the first AS, so that the first AS triggers the network reselection to the second network. For example, when the terminal initiates the calling procedure, the upper layer sends the first indication to the first NAS, and after receiving the first indication, the first NAS sends the second target indication to the first AS.

In another possible implementation manner of the embodiment of the present application, the first NAS obtaining the first target indication may also obtain the first message from the first network for the first NAS of the terminal. Alternatively, the first message may be a paging (paging) message. For example, the terminal is used AS a called party, and after receiving the paging message sent by the 5G network, the terminal sends the second target indication to the first AS of the terminal.

Alternatively, the upper layer of the terminal may be an IMS sub-layer.

In one possible implementation, since the first NAS determines to fall back to the second network, in order to make the IMS sublayer aware of the information, after the first NAS of the terminal acquires the first target indication, the method may further include: the first NAS of the terminal informs the IMS sublayer of the terminal to wait for the response of the second NAS of the terminal. For example, UE 5GNAS interactions with IMS: the UE 5G NAS informs the IMS layer that the UE is to initiate EPS fallback (EPS fallback), so the IMS sub-layer waits for a response of the EPS NAS (i.e., UE LTE NAS).

In one possible implementation manner, the first indication information may be carried in the paging message at the network side, where the first indication information includes at least one of the following: an indication of fallback to the second network, an indication that the network side supports fallback from the first network to the second network. For example, the paging message carries an EPS fallback indication (EPS fallback indication). In this possible implementation manner, the network side may instruct the terminal to fall back to the second network by carrying the first indication information in the paging message or instruct the terminal network side to support fall back from the first network to the second network, so that the first NAS of the terminal may send the second target indication to the first AS according to the first indication information, so AS to reselect to the second network.

In the foregoing possible implementation manner, some terminals may not have the capability of supporting the paging message carrying the indication of falling back to the second network, so, in order to enable the terminal to be consistent with the understanding of the network side, to be able to obtain the indication of falling back to the second network carried in the paging message, in one possible implementation manner, before the first NAS of the terminal receives the first message from the first network, the method may further include: and the terminal sends NAS information to a network side, wherein the NAS information carries second indication information, and the second indication information indicates that the terminal has the capability of supporting paging information carrying the first indication information. Alternatively, the NAS message may be a registration message, for example, an initial registration message, or a registration message for mobility registration update. One implementation is that a value of a bit of a 5GMM capability cell in the registration message is set to 1, for indicating that the terminal has the capability of supporting the paging message carrying the first indication information, and a value of the bit is set to 0, for indicating that the terminal does not have the capability of supporting the paging message carrying the first indication information.

In one possible implementation, in order to make the network side learn that the terminal falls back to the second network after receiving the paging message, the terminal may notify the network side when responding to the paging message to the network side. Thus, in this possible implementation, after receiving the paging message, the method may further comprise: and the terminal responds to the paging of the first network and sends a paging response, wherein the paging response carries an indication of falling back to the second network.

In one possible implementation, the paging response may include a service request message, and the indication to fall back to the second network may be an indication value in a request type cell in the service request message. That is, the terminal sets the value of the request type cell in the service request message to an indication value indicating fallback to the second network. With this possible implementation, the overhead of signaling can be reduced.

In another possible implementation, the paging response may include a service request message, and the indication of the fallback to the second network may be an EPSfallback cell in the service request message.

In one possible implementation, the sending, by the first NAS of the terminal, the second target indication to the first AS of the terminal may include: and the first NAS of the terminal sends a second target instruction to the first AS of the terminal according to the target information.

For example, the target information may include at least one of:

(1) The historical call information of the terminal, wherein the historical call information indicates that the historical voice service of the terminal in the first network is executed by falling back to the second network;

(2) The method comprises the steps of sending first indication information by network side equipment, wherein the first indication information comprises at least one of the following steps: an indication of fallback to the second network, an indication that the network side supports fallback from the first network to the second network. Optionally, the first indication information may be system information broadcasted by the network side device, or may also be information carried in a paging message of the paging terminal of the network side device, for example, in the foregoing possible implementation manner, the first indication information is carried in the paging message.

(3) And capability information of the terminal, wherein the capability information indicates that the terminal has the capability of falling back to the second network.

Of course, the method is not limited thereto, and in practical application, the first NAS may directly send the second target instruction to the first AS of the terminal after receiving the first target instruction, instead of determining to send the second target instruction to the first AS of the terminal according to the target information.

S312, the first AS of the terminal triggers the network reselection to the second network.

In the embodiment of the application, the first AS of the terminal can send an instruction to the second AS of the terminal, so that the second AS informs the second NAS of triggering reselection to the second network. Thus, in one possible implementation, S312 may include:

step 1, a first AS of the terminal sends a second indication to a second AS of the terminal, wherein the second indication comprises one of the following steps: an indication to fall back to the second network, an indication to redirect to the second network.

For example, the UE 5G AS interacts with the UE LTE AS, and the indication sent by the UE 5G AS to the UE LTE AS may be one of: the UE is to make an indication of EPS fallback, an indication of redirection to LTE.

And step 2, the second AS of the terminal informs the second NAS of the terminal to trigger reselection to a second network.

The second NAS and the second AS of the terminal may be NAS and AS corresponding to the second network of the terminal, for example, the second NAS of the terminal is LTE NAS of the terminal, or is an EMM, and the second AS of the terminal is LTE AS of the terminal.

In one possible implementation, the notifying, by the second AS of the terminal, the second NAS trigger reselection of the terminal to the second network may include:

Step 1, a second AS of the terminal sends a notification to a second NAS of the terminal, wherein the notification carries an instruction of falling back to a second network.

For example, the UE LTE AS may inform the UE that EMM needs EPS fallback.

Step 2, the second NAS of the terminal sends a third indication to the second AS of the terminal, where the third indication includes: an attach request or a TAU request.

Step 3, the second AS of the terminal initiates a radio resource control (Radio Resource Control, RRC) establishment procedure, and in the RRC establishment procedure, the second AS of the terminal sends a fourth indication to the base station, where the fourth indication includes: an indication to fall back to the second network, the fourth indication further comprising: an attach request message or a TAU request message.

For example, after triggering UE LTE cell selection and reselection, and discovering an allowed or suitable cell (allowed cell or suitable cell), the UE LTE AS initiates an RRC establishment procedure, optionally in which the UE LTE AS may send an indication of one of the following to a base station (e.g., eNB):

EPS fallback indication (UE to network);

-attach request；

-TAU request。

in one possible implementation manner, after the second NAS of the terminal receives the attach accept message of the network side in response to the attach request or the TAU accept message in response to the TAU request, the method may further include:

Step 1, a second NAS of the terminal establishes PDN connection for IMS service in the second network;

step 2, the second NAS of the terminal sends a response instruction to the IMS sublayer of the terminal, where the response instruction: an indication of success of PDN connection or EPS bearer establishment for IMS services.

For example, after the UE performs the LTE connection state, the attach procedure or TAU procedure is completed, and after the PDN connection for the IMS service is successfully established, the UE LTE NAS sends one of the following indications to the IMS layer:

-an indication of a successful PDN connection/EPS bearer establishment for IMS services;

-EPS bearer identification (EPS bearer identity, EBI).

In one possible implementation, the second AS may initiate the RRC establishment procedure after receiving an attach request or TAU request sent by the second NAS of the terminal. I.e. the second AS may initiate an RRC establishment procedure under the triggering of the second NAS.

Alternatively, in another possible implementation, the second AS may initiate the RRC establishment procedure while sending a notification to the second NAS of the terminal. Since the second AS has learned to fall back to the second network when sending the notification to the second NAS, the second AS may initiate the RRC establishment procedure at the same time to save time.

And S314, the terminal executes voice service through the second network.

For example, after a PDN connection establishment for an IMS service is successful, the second NAS of the terminal may interact with the IMS sub-layer, thereby performing a voice service.

According to the technical scheme provided by the embodiment of the application, the first NAS of the UE can acquire the capability information of the network for the voice service to fall back to 4G, when the UE triggers the calling voice or the called UE voice service, the first NAS of the UE can determine an instruction for sending the voice service to fall back to the second network or an instruction for redirecting the voice service to the second network to the first AS according to at least one of the capability information of the network side, the capability information of the first NAS and the historical call information, so that the first AS triggers the terminal to reselect to the second network, and the terminal residing in the first network can fall back to the second network quickly to execute the voice service.

In the embodiment of the application, the UE can directly reselect the cell to the second network to directly execute the voice service, thereby avoiding the process that the UE enters the connection state in the first network and then falls back to the second network, and further saving certain call delay.

The technical scheme provided by the embodiment of the application is described below by taking the 5G UE in an idle state as a called party or a calling party of voice service as an example.

In the embodiment of the application, the NG RAN or the AMF may send first capability indication information to the UE, where the first capability indication information is used to indicate that the network side has the capability of EPS fallback, that is, the network side supports EPS fallback. The voice service by the 5G UE may include the following steps.

Step 1.5G NAS decides to reselect to LTE according to the following indication, and executes EPS fallback, where the indication is one of the following forms:

the indication of the UE IMS layer may include one of:

-MMTel voice call indication or start indication ((start of) an MMTEL voice call from the upper layers);

-MMTel video talk indication or start indication ((start of) MMTEL video call from the upper layers);

-an IMS registration related signaling indication or start indication ((start of) an MO IMS registration related signalling from the upper layers);

-an SMSoIP indication or start indication ((start of) SMSoIP from the upper layers).

(II) indication of the network side, may include one of:

-paging message+system broadcast SIB (EPS fallback indication is included in SIB);

a paging message (which carries an indication of EPS fallback). In this case, the UE carries in a previously sent NAS message (e.g., registration message) a paging message (paging indication for EPS fallback) capability indication indicating that the terminal has an indication to support carrying EPS fallback, or other similar indication.

Step 2, after the UE 5G NAS (for example, may be a 5 GMM) receives the upper layer instruction in step 1, it is determined that the procedure of entering the 5G connection state is not initiated, but the UE actively triggers the idle state to reselect to LTE according to the following conditions:

UE history call information (UE history call information indicates that UE history calls are all voice calls acquired by EPS fallback);

-UE 5G AS provided information, for example: system broadcast (the system broadcast indicates that the network supports EPS fallback).

Optionally, for calling voice traffic, the UE 5G NAS may interact with IMS: the UE 5G NAS informs the IMS layer that the UE is to initiate EPS fallback, so the IMS layer waits for a response of EPS NAS (UE LTE NAS).

Step 3, UE 5G NAS (e.g. 5 GMM) interacts with UE 5G AS, the indication sent by 5GMM to 5G AS may indicate one of the following:

-the UE is to perform EPS fallback;

redirect to LTE (redirect to LTE).

Step 4, UE 5G AS interacts with UE LTE AS, and the indication sent by 5G AS to LTE AS may indicate one of the following:

-the UE is to perform EPS fallback;

redirect to LTE (redirect to LTE).

In step 5, the UE LTE AS notifies the UE EMM that the EPS fallback is to be performed, and the UE EMM sends an attach request (attach request) or a TAU request (request) to the UE LTE AS. Optionally, UE LTE AS synchronization triggers UE LTE cell selection and reselection.

Step 6, after triggering UE LTE cell selection and reselection by the UE LTE AS and discovering an allowed or suitable cell (allowed cell or suitable cell), the UE LTE AS initiates an RRC establishment procedure, optionally, during which the UE LTE AS may send an indication to the network eNB, where the indication may include one of the following:

EPS fallback indication (UE to network);

-attach request；

-TAU request。

step 7, after the UE enters the LTE connection state and completes an attach procedure or a TAU procedure, and after a PDN connection for an IMS service is successfully established, the UE LTE NAS sends one of the following indications to the IMS layer:

-a PDN connection/EPS bearer establishment for IMS services is successful;

-EBI。

step 8, interaction between the LTE NAS and the IMS sub-layer realizes voice service, and optionally, the step 8 may include the following steps:

at step 8a, emm informs ESM MM connection establishment.

In step 8b, the emm informs the IMS sub-layer that the UE is registered with the EPS.

In step 8c, the emm informs the ESM layer of the beer status information.

The technical scheme provided by the embodiment of the application is explained below by taking calling voice service as an example through interaction of all layers in the UE.

Fig. 4 is a flow chart of a method for implementing a calling voice service according to an embodiment of the present application, and as shown in fig. 4, the method mainly includes the following steps.

S401, the UE needs to initiate an MO call, and the IMS sub-layer sends a related indication to the UE 5G NAS layer, where the related indication may be one of the following:

-(start of)an MMTEL voice call from the upper layers；

-(start of)MMTEL video call from the upper layers；

-(start of)an MO IMS registration related signaling from the upper layers；

-(start of)SMSoIP from the upper layer。

s402, after receiving the upper layer instruction in S401, the UE 5G NAS (5 GMM in the drawing) decides not to initiate a procedure of entering the 5G connection state, but to actively trigger the idle state to reselect to LTE by the UE according to the following conditions:

Optionally, the method may further include S402a, UE 5G NAS interaction with IMS: the UE 5G NAS informs the IM sub-S layer that the UE is to initiate EPS fallback, and therefore the IMs sub-layer waits for a response from the EPS NAS (i.e. UE LTE NAS). Normally, the UE 5G NAS should directly establish the related PDU session after receiving the above indication of the IMS sublayer, and/or, the QoS flows (QoS flow for IMS signaling, MMTEL voice, MMTEL video or smoip) of the IMS signal, MMTEL video or SMSoIP, and feed back the establishment success message to the IMS layer, however, since the UE 5G NAS determines to fall back to the EPS, the UE 5G NAS notifies the IMS sublayer to wait for the response of the EPS NAS (UE LTE NAS).

S403, the UE 5G NAS (5 GMM in the figure) interacts with the UE 5G AS, and the indication sent by the 5GMM to the 5G AS may indicate one of the following:

-the UE is to perform EPS fallback;

-redirecting to LTE.

S404, UE 5G AS interacts with UE LTE AS, and the indication sent by 5G AS to LTE AS may indicate one of the following:

-the UE is to perform EPS fallback;

-redirecting to LTE.

S405, the UE LTE AS notifies the UE EMM that EPS fallback is to be performed, and the UE EMM sends an attach request or TAU request to the UE LTE AS. Optionally, UE LTE AS synchronization triggers UE LTE cell selection and reselection.

S406. after the UE LTE AS triggers UE LTE cell selection and reselection and discovers an allowed or suitable cell (allowed cell or suitable cell), the UE LTE AS initiates an RRC setup procedure. Optionally, during RRC establishment, the UE LTE AS may send an indication to the network eNB, including one of:

EPS fallback indication (UE to network);

-attach request；

-TAU request。

s407. the lte NAS receives an attach accept message (attach accept) of the network side in response to the attach request or a TAU accept message (TAU accept) in response to the TAU request.

Interaction of lte NAS and IMS layers. Specifically, as shown in fig. 5, the following S408a, S408b, S408c, and S408d may be included.

S408a, EMM informs ESM MM connection establishment.

S408b, the EMM informs the IMS sub-layer that the UE is registered with the EPS.

S408c, the EMM informs ESM layer of bearing status (bearer status) information.

S408d, after the UE enters the LTE connection state, completing the attach procedure or TAU procedure, and after successfully establishing a PDN connection for an IMS service, the UE LTE NAS sends one of the following indications to the IMS sub-layer:

-an indication of success of PDN connection or EPS bearer (bearer) establishment for IMS traffic;

-EBI。

according to the technical scheme provided by the embodiment of the application, when the UE triggers the calling voice service, the UE can actively trigger the network reselection to the 4G cell for acquiring the VoLTE service according to at least one of the capability information of the network side, the historical call information and the own capability information. The UE is prevented from entering a connection state in the 5G network and then falling back to the 4G network, so that a certain call delay can be saved.

The technical scheme provided by the embodiment of the application is described below by taking the called voice service as an example through interaction of all layers in the UE.

Fig. 5 is a flow chart illustrating a method for implementing a called voice service in an embodiment of the present application, and as shown in fig. 5, the method mainly includes the following steps.

S501. the ue receives an indication of the network, which may be one of:

Paging message+system broadcast SIB (SIB carries EPS fallback indication or SIB carries indication information indicating that the network side supports fallback from 5G to 4G);

-paging message (carrying an indication of EPS fallback) in which case the UE carries an indication of capability of the terminal to have paging messages (paging indication for EPS fallback) supporting an indication of EPS fallback, or similar other indication, in a previously sent NAS message (e.g. registration message).

S502, after the UE 5G NAS (5 GMM in the figure) receives the upper layer instruction in S501, it is determined that the procedure of entering the 5G connection state is not initiated, but the UE actively triggers the idle state to reselect to LTE according to the following conditions:

-UE 5G AS provided information, for example: system broadcasting (the system broadcasting indicates that the network supports EPS fallback);

optionally, as shown in fig. 5, the method may further include S502a, UE 5G NAS interaction with IMS: the UE 5G NAS informs the IMS layer that the UE is to initiate EPS fallback, so the IMS sub-layer waits for a response of EPS NAS (UE LTE NAS). Normally, the UE 5G NAS should directly establish the related PDU session after receiving the indication in S501, and/or, the IMS signal, MMTEL voice, MMTEL video or QoS flow of smoip (QoS flow for IMS signaling, MMTEL voice, MMTEL video, SMSoIP), and feed back the establishment success message to the IMS layer, however, since the UE 5G NAS determines to drop back to the EPS, the UE 5G NAS notifies the IMS sub-layer to wait for the response of the EPS NAS (UE LTE NAS).

In addition, as shown in fig. 5, the method may further include: s502b, the UE 5G NAS responds to paging of the 5G network and sends a paging response to the 5GS, wherein the paging response carries an EPS fallback indication.

In one possible implementation, the paging response may include a service request message, and the indication of EPS fallback may be an indication value in a request type cell in the service request message. That is, the terminal sets the value of the request type cell in the service request message to an instruction value indicating EPS fallback. With this possible implementation, the overhead of signaling can be reduced. In another possible implementation manner, the paging response may include a service request message, and the indication of the EPS fallback may be an EPS fallback cell in the service request message.

S503, the UE 5G NAS (5 GMM in the figure) interacts with the UE 5G AS, and the indication sent by the 5GMM to the 5G AS may indicate one of the following:

-the UE is to perform EPS fallback;

-redirect to LTE。

s504, the UE 5G AS interacts with the UE LTE AS, and the indication sent by the 5G AS to the LTE AS may indicate one of the following:

-the UE is to perform EPS fallback;

-redirecting to LTE.

S505, the UE LTE AS informs the UE EMM that EPS fallback is to be performed, and the UE EMM sends an attach request or TAU request to the UE LTE AS. Optionally, UE LTE AS synchronization triggers UE LTE cell selection and reselection.

S506.UE LTE AS triggers UE LTE cell selection and reselection, after finding a permitted or suitable cell (allowed cell or suitable cell), UE LTE AS initiates RRC setup procedure. Optionally, during RRC establishment, the UE LTE AS may send an indication to the network eNB, including one of:

EPS fallback indication (UE to network);

-attach request；

-TAU request。

the lte NAS receives an attach accept message (attach accept) of the network side in response to the attach request or a TAU accept message (TAU accept) of the TAU request.

Interaction of lte NAS and IMS layers. Specifically, as shown in fig. 5, the following S508a, S508b, S508c, and S508d may be included.

S508a, EMM informs ESM MM connection establishment.

S508b, EMM informs IMS sub-layer UE to register with EPS.

S508c, the EMM informs ESM layer of bearing status (bearer status) information.

S508d, after the UE enters the LTE connected state, completing an attach procedure or a TAU procedure, and after successfully establishing a PDN connection for an IMS service, the UE LTE NAS sends one of the following indications to the IMS sub-layer:

-EBI。

according to the technical scheme provided by the embodiment of the application, when the UE triggers the called voice service, the UE can actively trigger the network reselection to the 4G cell for triggering the VoLTE service according to at least one of the capability information of the network side, the historical call information and the capability information of the UE. The UE is prevented from entering a connection state in the 5G network and then falling back to the 4G network, so that a certain call delay can be saved.

According to the implementation method of the voice service provided by the embodiment of the application, the execution main body can be an implementation device of the voice service. In the embodiment of the application, the implementation method of executing the voice service by the implementation device of the voice service is taken as an example, and the implementation device of the voice service provided by the embodiment of the application is described.

Fig. 6 shows a schematic structural diagram of a device for implementing a voice service according to an embodiment of the present application, where the device may be applied to a terminal, and as shown in fig. 6, the device mainly includes: an acquisition module 601, a triggering module 602 and an execution module 603.

In the embodiment of the present application, the obtaining module 601 is configured to send, after obtaining, by a first NAS of a terminal residing in a first network, a second target indication to a first access stratum AS of the terminal, where the second target indication includes one of the following: an indication to fall back to the second network, an indication to redirect to the second network, the first NAS of the terminal corresponding to the first network; a triggering module 602, configured to trigger, by using a first AS of the terminal, a network reselection to a second network, where the first AS of the terminal corresponds to the first network; an execution module 603, configured to execute a voice service through the second network.

In one possible implementation, the acquiring module 601 acquires the first target indication includes at least one of:

acquiring a first indication from an upper layer of the terminal through a first NAS of the terminal; or alternatively, the process may be performed,

and acquiring a first message from a first network through a first NAS of the terminal, wherein the first message comprises a paging message.

In one possible implementation, as shown in fig. 6, the apparatus further includes: and the sending module 604 is configured to respond to the paging message from the first network, and send a paging response, where the paging response carries an indication that the paging message falls back to the second network.

In one possible implementation manner, the paging message carries first indication information, where the first indication information includes at least one of the following: an indication of fallback to the second network, an indication that the network side supports fallback from the first network to the second network; the sending module 604 is further configured to send a NAS message to a network side, where the NAS message carries second indication information, and the second indication information indicates that the terminal has a capability of supporting a paging message carrying the first indication information.

In one possible implementation, the triggering module 602, by triggering the first AS of the terminal, to perform network reselection to the second network includes:

Sending, by the first AS of the terminal, a second indication to a second AS of the terminal, wherein the second indication includes one of: an indication to fall back to the second network, an indication to redirect to the second network;

and notifying a second NAS trigger of the terminal to reselect to a second network through a second AS of the terminal.

In one possible implementation, the triggering module 602 is further configured to:

sending a notification to a second NAS of the terminal through a second AS of the terminal, wherein the notification carries an indication of falling back to a second network;

sending, by the second NAS of the terminal, a third indication to a second AS of the terminal, where the third indication includes: an attach request or tracking area update TAU request;

initiating a Radio Resource Control (RRC) establishment process by a second AS of the terminal, and sending a fourth indication to a base station in the RRC establishment process, wherein the fourth indication comprises: an indication to fall back to the second network, the fourth indication further comprising: an attach request message or a tracking area update TAU request message.

In one possible implementation, as shown in fig. 6, the apparatus further includes: and the receiving module is used for receiving an attachment acceptance message of the network side responding to the attachment request or a TAU acceptance message of the TAU request.

In one possible implementation manner, the triggering module 602 is further configured to establish a PDN connection for an IMS service in the second network, and send, through the second NAS of the terminal, a response indication to an IMS sub-layer of the terminal, where the response indication is: an indication of success of PDN connection or EPS bearer establishment for IMS services.

In one possible implementation, the triggering module 602 initiates a radio resource control RRC establishment procedure through a second AS of the terminal, including:

after receiving the attach request or tracking area update TAU request, initiating a radio resource control RRC establishment procedure through a second AS of the terminal; or alternatively, the process may be performed,

and simultaneously sending a notification to a second NAS of the terminal, and initiating a Radio Resource Control (RRC) establishment process through a second AS of the terminal.

In one possible implementation, the upper layer of the terminal includes: an IMS sublayer; the obtaining module 601 is further configured to notify, after obtaining, by the first NAS of the terminal, a first indication from an IMS sublayer, the IMS sublayer of the terminal to wait for a response of the second NAS of the terminal.

In one possible implementation manner, the acquiring module 601 sends, through the first NAS of the terminal, a second target indication to the first access stratum AS of the terminal, including: and sending a second instruction to a first access stratum AS of the terminal through the first NAS of the terminal according to the target information.

The device for implementing the voice service in the embodiment of the application can be an electronic device, for example, an electronic device with an operating system, or can 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 device for implementing voice service provided by the embodiment of the present application can implement each process implemented by the terminal in the method embodiments of fig. 3 to 5, and achieve the same technical effects, and for avoiding repetition, the description is omitted here.

Optionally, as shown in fig. 7, the embodiment of the present application further provides a communication device 700, including a processor 701 and a memory 702, where the memory 702 stores a program or an instruction that can be executed on the processor 701, for example, when the communication device 700 is a terminal, the program or the instruction is executed by the processor 701 to implement each step of the embodiment of the implementation method of the voice service, and the same technical effects can be achieved, so that repetition is avoided and no further description is given here.

The embodiment of the application also provides a terminal which comprises a processor and a communication interface, wherein the processor is used for realizing the steps of the implementation method embodiment of the voice service, and the communication interface is used for communicating with external equipment. 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. 8 is a schematic diagram of a hardware structure of a terminal for implementing an embodiment of the present application.

The terminal 800 includes, but is not limited to: at least part of the components of the radio frequency unit 801, the network module 802, the audio output unit 803, the input unit 804, the sensor 805, the display unit 806, the user input unit 807, the interface unit 808, the memory 809, and the processor 810, etc.

Those skilled in the art will appreciate that the terminal 800 may further include a power source (e.g., a battery) for powering the various components, and that the power source may be logically coupled to the processor 810 by a power management system for performing functions such as managing charging, discharging, and power consumption by the power management system. The terminal structure shown in fig. 8 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 appreciated that in embodiments of the present application, the input unit 804 may include a graphics processing unit (Graphics Processing Unit, GPU) 8041 and a microphone 8042, with the graphics processor 8041 processing image data of still pictures or video obtained by an image capturing device (e.g., a camera) in a video capturing mode or an image capturing mode. The display unit 806 may include a display panel 8061, and the display panel 8061 may be configured in the form of a liquid crystal display, an organic light emitting diode, or the like. The user input unit 807 includes at least one of a touch panel 8071 and other input devices 8072. Touch panel 8071, also referred to as a touch screen. The touch panel 8071 may include two parts, a touch detection device and a touch controller. Other input devices 8072 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 the embodiment of the present application, after receiving downlink data from the network side device, the radio frequency unit 801 may transmit the downlink data to the processor 810 for processing; in addition, the radio frequency unit 801 may send uplink data to the network side device. In general, the radio frequency unit 801 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 809 may be used to store software programs or instructions and various data. The memory 809 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 809 may include volatile memory or nonvolatile memory, or the memory 809 may include both volatile and nonvolatile memory. The non-volatile memory may be a Read-only memory (ROM), a programmable Read-only memory (ProgrammableROM, PROM), an erasable programmable Read-only memory (ErasablePROM, EPROM), an electrically erasable programmable Read-only memory (ElectricallyEPROM, EEPROM), or a flash memory, among others. 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 809 in embodiments of the application includes, but is not limited to, these and any other suitable types of memory.

The processor 810 may include one or more processing units; optionally, the processor 810 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 810.

The processor 810 is configured to send a second target indication to a first access stratum AS of a terminal residing in a first network after acquiring the first target indication through a first NAS of the terminal; triggering a network to reselect to a second network through a first AS of the terminal; executing voice service through the second network; wherein the second target indication comprises one of: an indication to fall back to the second network, an indication to redirect to the second network, the first NAS of the terminal corresponding to the first network, the first AS of the terminal corresponding to the first network.

The embodiment of the application also provides a readable storage medium, on which a program or an instruction is stored, which when executed by a processor, implements each process of the implementation method embodiment of the voice service, and can achieve the same technical effect, so that repetition is avoided, and no further description is provided 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, which comprises a processor and a communication interface, wherein the communication interface is coupled with the processor, and the processor is used for running programs or instructions to realize the processes of the embodiment of the implementation method of the voice service, and the same technical effects can be achieved, so that repetition is avoided, and the description is omitted here.

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 embodiment of the present application further provides 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 above-mentioned embodiment of the method for implementing a voice service, and the same technical effects can be achieved, so that repetition is avoided, and details are not repeated here.

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 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 solution 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 (e.g. ROM/RAM, magnetic disk, optical disk) comprising 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 according to 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 having ordinary skill in the art without departing from the spirit of the present application and the scope of the claims, which are to be protected by the present application.

Claims

1. The method for realizing the voice service is characterized by comprising the following steps:

after a first non-access stratum (NAS) of a terminal residing in a first network acquires a first target instruction, sending a second target instruction to a first Access Stratum (AS) of the terminal, wherein the second target instruction comprises one of the following components: an indication to fall back to the second network, an indication to redirect to the second network, the first NAS of the terminal corresponding to the first network;

triggering a first AS of the terminal to perform network reselection to a second network, wherein the first AS of the terminal corresponds to the first network;

and the terminal executes voice service through the second network.

2. The method of claim 1, wherein the first NAS of the terminal obtaining the first target indication comprises:

The method comprises the steps that a first NAS of the terminal obtains a first indication from an upper layer of the terminal; or alternatively, the process may be performed,

the first NAS of the terminal obtains a first message from a first network.

3. The method of claim 2, wherein the first indication comprises one of:

a multimedia telephony service MMTel voice call indication;

MMTel voice call start indication;

MMTel video call indication;

MMTel video call start indication;

an indication of signaling related to IMS registration of an uplink IP multimedia subsystem;

an uplink IMS registration related signaling start instruction;

an IP-based short message SMSoIP indication;

SMSoIP start indication.

4. The method of claim 2, wherein the first message comprises: paging messages for paging the terminal.

5. The method of claim 1, wherein the first AS of the terminal triggers the terminal to reselect to the second network, comprising:

the first AS of the terminal sends a second indication to a second AS of the terminal, wherein the second indication comprises one of the following: an indication to fall back to a second network, an indication to redirect to a second network, a second AS of the terminal corresponding to the second network;

And the second AS of the terminal informs a second NAS of the terminal to trigger reselection to a second network, wherein the second NAS of the terminal corresponds to the second network.

6. The method of claim 5, wherein the second AS of the terminal informs the second NAS of the terminal to trigger reselection to a second network, comprising:

the second AS of the terminal sends a notification to the second NAS of the terminal, wherein the notification carries an indication of falling back to a second network;

the second NAS of the terminal sends a third indication to a second AS of the terminal, wherein the third indication comprises: an attach request or tracking area update TAU request;

the second AS of the terminal initiates a Radio Resource Control (RRC) establishment process, and in the RRC establishment process, the second AS of the terminal sends a fourth indication to the base station, wherein the fourth indication comprises: an indication to fall back to the second network, the fourth indication further comprising: an attach request message or a tracking area update TAU request message.

7. The method of claim 6, wherein after the second NAS of the terminal sends the third indication to the second AS of the terminal, the method further comprises: and the second NAS of the terminal receives an attach accept message of the network side responding to the attach request or a TAU accept message responding to the TAU request.

8. The method of claim 7, wherein after the second NAS of the terminal receives the attach accept message of the network side in response to the attach request or the TAU accept message in response to the TAU request, the method further comprises:

a second NAS of the terminal establishes PDN connection for IMS service in the second network;

the second NAS of the terminal sends a response instruction to an IMS sublayer of the terminal, wherein the response instruction is as follows: an indication of success of PDN connection or EPS bearer establishment for IMS services.

9. The method of claim 6, wherein the second AS of the terminal initiates a radio resource control, RRC, establishment procedure comprising:

after receiving an attachment request or a TAU request sent by a second NAS of the terminal, a second AS of the terminal initiates an RRC establishment procedure; or alternatively, the process may be performed,

the second AS of the terminal initiates an RRC establishment procedure while sending a notification to the second NAS of the terminal.

10. The method according to any of claims 2 to 9, wherein the upper layer of the terminal comprises: IMS sublayers.

11. The method of claim 10, wherein after the first NAS of the terminal obtains the first indication from the IMS sublayer of the terminal, the method further comprises:

The first NAS of the terminal informs the IMS sublayer of the terminal to wait for the response of the second NAS of the terminal.

12. The method according to any of the claims 1 to 9, characterized in that the first NAS of the terminal sends a second target indication to the first access stratum AS of the terminal, comprising:

and the first NAS of the terminal sends a second target instruction to a first access stratum AS of the terminal according to the target information.

13. The method of claim 12, wherein the target information comprises at least one of:

historical call information of the terminal, wherein the historical call information indicates that a historical voice service of the first network is performed by falling back to the second network;

the method comprises the steps of sending first indication information by network side equipment, wherein the first indication information comprises at least one of the following steps: an indication of fallback to the second network, an indication that the network side supports fallback from the first network to the second network;

and capability information of the terminal, wherein the capability information indicates that the terminal has the capability of falling back to the second network.

14. The method of claim 13, wherein the first indication information sent by the network side device includes:

System information broadcast by network side equipment; or alternatively, the process may be performed,

the network side equipment pages the information carried in the paging message of the terminal.

15. The method according to any of claims 1 to 9, wherein the first network is a 5G network and the second network is an evolved packet system EPS network.

16. The method according to any of claims 1 to 9, wherein the indication of fallback to the second network is an EPS fallback indication.

17. A voice service implementation apparatus, comprising:

the acquiring module is configured to send a second target indication to a first access stratum AS of a terminal residing in a first network after acquiring the first target indication through a first NAS of the terminal, where the second target indication includes one of: an indication to fall back to the second network, an indication to redirect to the second network, the first NAS of the terminal corresponding to the first network;

the triggering module is used for triggering the network to be reselected to a second network through a first AS of the terminal, wherein the first AS of the terminal corresponds to the first network;

and the execution module is used for executing voice service through the second network.

18. 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 of implementing a voice service according to any one of claims 1 to 16.

19. A readable storage medium, characterized in that the readable storage medium stores thereon a program or instructions, which when executed by a processor, implement the steps of the method for implementing a voice service according to any of claims 1 to 16.