WO2013097113A1

WO2013097113A1 - Method and device for keeping call continuity

Info

Publication number: WO2013097113A1
Application number: PCT/CN2011/084815
Authority: WO
Inventors: 周敬华; 张朝辉; 黄锴
Original assignee: 华为技术有限公司
Priority date: 2011-12-28
Filing date: 2011-12-28
Publication date: 2013-07-04
Also published as: CN102577510A; CN102577510B

Abstract

The embodiments of the present invention relate to a method and device for keeping call continuity. The method includes: receiving a first Internet Protocol multimedia subsystem (IMS) session handover message sent by a handover entity, the first IMS session handover message being used for giving an indication to employ a second session to replace a first session during a single radio voice call continuity (SRVCC) process, the first IMS session handover message carrying the session identifier of the first session; searching for the first session according to the session identifier of the first session and acquiring session description protocol (SDP) information corresponding to a far end media path of the first session; and sending a second IMS session handover message to a service centralization and continuity application server (SCC AS), the second IMS session handover message carrying SDP information corresponding to the far end media path of the first session. The embodiments of the present invention ensure user call continuity is kept during the SRVCC process.

Description

Method and device for maintaining call continuity

The present invention relates to the field of communications technologies, and in particular, to a method and device for maintaining call continuity. BACKGROUND OF THE INVENTION Long Term Evolution (LTE) Voice over Voice (VOLTE) is a wireless access mode in a full packet mode using an Internet Protocol Multimedia System (IMS) network. The technology of interpersonal communication, as the data traffic gradually surpasses voice to become the mainstream of user consumption, the application of all-package wireless networks such as LTE is increasingly widespread.

Single Radio Voice Call Continuity (SRVCC) is a technology that provides voice communication under VoLTE to Circuit Switched (CS) to enable users' voice services to cross LTE. It is not necessary to re-establish after the boundary to enhance the user experience.

In the prior art, when a user roams to a visited network and triggers an SRVCC handover, a border gateway is deployed between the operators in the media path switching process on the access side (for example, an Interconnection Border Control Function (IBCF) function. Or the Transition Gateway (TrGW) may modify the Session Description Protocol (SDP) information by performing IP address translation, thereby triggering the SCC AS to perform the operation of updating the remote media path, which may cause the user to call the media. Interrupt, affecting the user's normal voice service. SUMMARY OF THE INVENTION Embodiments of the present invention provide a method and apparatus for maintaining call continuity to maintain continuity of user calls during SRVCC.

In one aspect, the embodiment of the present invention provides a method for maintaining a call continuity, including: receiving a first Internet Protocol Multimedia Subsystem IMS Session Switch message sent by an access switching entity, where the first IMS session switch message is used to indicate that Single wireless voice call continuous SRVCC cut The first session is replaced by the second session, and the first IMS session switching message carries the session identifier of the first session;

And searching for the first session according to the session identifier of the first session, and acquiring session description protocol SDP information corresponding to the remote media path of the first session;

Sending a second IMS session switch message to the service central server and the continuous application server SCC AS, where the second IMS session switch message carries the SDP message corresponding to the remote media path of the first session.

The embodiment of the invention further provides a border gateway, including:

a receiver, configured to receive a first Internet Protocol Multimedia Subsystem IMS Session Switch message sent by the access switching entity, where the first IMS session switch message is used to indicate that the second session is replaced in a single radio voice call continuous SRVCC handover process. a first session, where the first IMS session switching message carries a session identifier of the first session;

a processor, configured to search for the first session according to the session identifier of the first session, and obtain session description protocol SDP information corresponding to the remote media path of the first session;

And a sender, configured to send a second IMS session switching message to the service aggregation and the continuous application server SCC AS, where the second IMS session switching message carries the SDP information corresponding to the remote media path of the first session.

In another aspect, the embodiment of the present invention further provides a method for maintaining a call continuity, including: receiving a single radio voice call continuous SRVCC handover request sent by a mobile switching center MSC server or a media gateway MGW;

Returning an SRVCC handover response to the MSC server or the MGW;

Sending an access switch message to the border gateway, so that the border gateway forwards the access switch message to the service set and the continuous application server SCC AS, where the access switch message is used to indicate that the first time is maintained during the SRVCC handover process. The remote media path of the session.

An embodiment of the present invention further provides an access switching entity, including:

a receiver, configured to receive a single voice call continuous SRVCC handover request sent by the mobile switching center MSC server or the media gateway MGW;

a transmitter, configured to send an SRVCC handover response to the MSC server or the MGW, and configured to send an access handover message to the border gateway, so that the border gateway forwards the access handover message to the service centralized and continuous application server SCC AS, the access switch message is used to indicate that The remote media path of the first session is maintained during the SRVCC handover.

Returning an SRVCC handover response to the MSC server or the MGW;

After the set time is reached, the Internet Protocol Multimedia Subsystem IMS session switch request is sent to the service set and the continuous application server SCC AS, where the IMS session switch message is used to replace the first session with the second session in the SRVCC handover process, The IMS session switching message carries the SDP information corresponding to the access side media path of the second session, so that the SCC AS corresponds to the access side media path of the second session after the access side media path is updated. The SDP information updates the remote media path of the second session.

a transmitter, configured to return an SRVCC handover response to the MSC server or the MGW; and configured to send an Internet Protocol Multimedia Subsystem IMS session handover request to the service set and the continuous application server SCC AS after the set time is reached, where the IMS session The switching message is used to indicate that the first session is replaced by the second session in the SRVCC handover process, where the IMS session switching message carries the SDP information corresponding to the access side media path of the second session, so that the SCC AS is in the After the access side media path is updated, the remote media path of the second session is updated according to the SDP information corresponding to the access side media path of the second session.

The method and the device for maintaining the continuity of the call provided by the embodiment of the present invention, on the one hand, the SDP corresponding to the remote media path corresponding to the original session is obtained by the border gateway according to the original session identifier, and the SDP information is carried in the IMS session switching message and sent to the SCC. The AS is configured to prevent the SCC AS from updating the remote media path when the access side media path is updated, so as to maintain the continuity of the user call during the SRVCC process; on the one hand, the remote media path of the original session is maintained during the SRVCC process, thereby avoiding the SCC The AS updates the remote media path when the access side media path is updated, so as to maintain the continuity of the user call in the SRVCC process; on the other hand, the IMS session switching message is sent to the border gateway by the access switching entity delay, so that the SCC AS The remote media path is updated after the access side media path is updated, thereby maintaining the continuity of the user call during the SRVCC process. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the embodiments or the description of the prior art will be briefly described below, and obviously, in the following description The drawings are only some of the embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

1 is a flow chart of an embodiment of a method for maintaining call continuity according to the present invention; FIG. 2 is a flowchart of still another embodiment of a method for maintaining call continuity according to the present invention; Method flow chart of another embodiment; FIG. 4 is a flow chart of an embodiment of a method for maintaining call continuity provided by the present invention; FIG. 5 is a flow chart of still another embodiment of a method for maintaining call continuity according to the present invention; FIG. 7 is a flowchart of an embodiment of a method for maintaining call continuity according to the present invention; FIG. 8 is a flowchart of a method for maintaining call continuity provided by the present invention; FIG. 9 is a schematic structural diagram of an embodiment of a border gateway according to the present invention;

FIG. 10 is a schematic structural diagram of an embodiment of a service centralized and continuous application server provided by the present invention; FIG.

FIG. 11 is a schematic structural diagram of an embodiment of an access switching entity according to the present invention;

12 is a schematic structural diagram of another embodiment of a service centralized and continuous application server according to the present invention;

FIG. 13 is a schematic structural diagram of still another embodiment of an access switching entity according to the present invention; FIG. 14 is a schematic structural diagram of another embodiment of an access switching entity according to the present invention. The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. example. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

FIG. 1 is a flowchart of an embodiment of a method for maintaining call continuity according to the present invention, as shown in FIG. 1 As shown, the method includes:

S101: Receive a first Internet Protocol Multimedia Subsystem IMS Session Switch message sent by the access switching entity, where the first IMS session switch message is used to replace the first session with the second session in a single wireless voice call continuous SRVCC handover process, where The IMS session switching message carries the session identifier of the first session;

5102. Search for the first session according to the session identifier of the first session, and obtain session description protocol SDP information corresponding to the remote media path of the first session.

5103. Send a second IMS session switching message to the service aggregation and the continuous application server SCC AS, where the second IMS session switching message carries the SDP information corresponding to the remote media path of the first session.

The execution body of the above steps is the border gateway of the IMS network to which the calling party and the called party belong, for example: IBCF/TrGW. The border gateway may also be an entity having an Application Level Gateway (ALG) function, such as an agent call session control function (P-CSCF).

The access switching entity includes an Access Transfer Gateway (ATGW) and an Access Transfer Control Function (ATCF) that controls the ATGW. When the calling party sends a call invitation to the called party, the two parties complete the call setup. The media path is divided into two parts: the packet switch (PS) access path and the remote media path by the ATGW. When the call occurs SRVCC handover, the Mobile Switching Center (MSC) server (Server) or the media gateway ( Media Gateway, MGW) first initiates the media path switch of the access side to the ATCF/ATGW. After the ATCF/ATGW cuts the media path of the access side to the MSC server or the MGW, the media path of the access side is switched from the PS access path to CS access path.

After the CS access path establishment is completed on the access side, the ATCF/ATGW sends a first IMS session switch message to the IBCF/TrGW. The first session is an original session established between the calling party and the called party. The first IMS session switching message carries the session identifier of the first session.

After receiving the first IMS session switching message, the IBCF/TrGW may find the first session according to the session identifier of the first session carried in the first IMS session switching message, and obtain the SDP corresponding to the remote media path of the first session. information.

The IBCF/TrGW may carry the SDP information corresponding to the remote media path of the first session in the first IMS session switching message and send it to the service set and the continuous application server (Service). The first IMS session switching message carrying the SDP information corresponding to the remote media path of the first session is referred to as a second IMS session switching message. The IBCF/TrGW sends a second IMS session switch message to the SCC AS to instruct the SCC AS to replace the first session with the second session in the SRVCC process.

After receiving the second IMS session switching message sent by the IBCF/TrGW, the SCC AS can obtain the SDP information corresponding to the remote media path of the first session from the second IMS session switching message, because the calling party and the called party During the process of replacing the original session (the first session) with the second session, the SDP information corresponding to the remote media path does not change. Therefore, the SCC AS does not need to update the remote media path, thereby avoiding updating the remote media path. The resulting SRVCC handover is interrupted, maintaining the continuity of user calls during the SRVCC process.

In the method for maintaining the continuity of the call provided by the embodiment, the border gateway obtains the SDP corresponding to the remote media path corresponding to the original session according to the original session identifier, and carries the SDP information in the IMS session switch message to the SCC AS to avoid the SCC AS. The remote media path is updated when the access side media path is updated, thereby achieving continuity of the user call during the SRVCC process.

2 is a flow chart of still another embodiment of a method for maintaining call continuity according to the present invention.

As shown in 2, the method includes:

S201: Receive a second Internet Protocol Multimedia Subsystem IMS Session Switch message, where the second IMS session switch message is used to replace the first session with the second session in a single radio voice call continuous SRVCC handover process, where the second IMS session The SDP information corresponding to the remote media path of the first session is carried in the handover message;

The remote media path of the second session is maintained as the remote media path of the first session according to the SDP information corresponding to the remote media path of the first session.

The execution body of the above steps is SCC AS.

If the SCC AS and the border gateway (for example: IBCF/TrGW, etc.) further include a query CSCF (Interrogating CSCF, I-CSCF) or a serving CSCF (Serving CSCF, S-CSCF), the border gateway can pass the I/S-CSCF. Sending a second IMS session switch message to the SCC AS; if the SCC AS is directly connected to the border gateway, the border gateway may directly send a second IMS session switch message to the SCCAS.

After receiving the second IMS session switching message, the SCC AS carries the SDP information carried in the second IMS session switching message and the remote media path of the first session (original session) saved by the SCC AS. The corresponding SDP information is compared. In the embodiment of the present invention, the SCC information received by the SCC AS in the second IMS session switching message is the SDP information corresponding to the remote media path of the first session, that is, the calling party and the During the process of replacing the original session (the first session) between the calling parties and the second session, the SDP information corresponding to the remote media path does not change. Therefore, the SCC AS does not need to update the remote media path, thereby avoiding updating the remote media. The interruption of the SRVCC handover caused by the path maintains the continuity of the user's call during the SRVCC process.

In the method for maintaining the continuation of the call, the border gateway obtains the SDP information corresponding to the remote media path of the original session according to the original session identifier, and carries the SDP information in the IMS session switch message to the SCC AS, and the SCC AS receives the SDP information. After the IMS session switching message is compared, the SDP information carried in the IMS session switching message is compared with the SDP information corresponding to the remote media path of the original session. If the comparison result is the same, the SCC AS does not need to update the remote media path, thereby avoiding the SCC. The AS updates the remote media path when the access side media path is updated, so as to maintain the continuity of the user call during the SRVCC process.

The embodiment shown in FIG. 1 and FIG. 2 respectively describes a method for maintaining call continuity provided by the present invention from the border gateway side (for example, IBCF/TrGW, etc.) and the SCC AS side, and the implementation provided in FIG. 1 and FIG. 2 will be provided below. The complete implementation scenario of the original session establishment process of the calling party and the called party and the process of SRVCC handover. As shown in FIG. 3, in this embodiment, the calling party is represented by UE1, and the called party is represented by UE2. The embodiment specifically includes the following steps:

S301. The ATCF/ATGW receives the call invitation message (INVITE) sent by the UE1.

S302: The ATCF determines that the media path is to be anchored, and the ATCF can process the media resource in the ATGW, generate the SDP information corresponding to the access side media path of the first session (SDP1), and carry the SDP1 in the call invitation message. Give IBCF/TrGW.

The ATCF can process the media resources in the allocated ATGW by using the existing method, and generate the SDP corresponding to the access side media path of the first session, where the first session is the original session established before the SRVCC handover between the UE1 and the UE2. . In this embodiment, the SDP corresponding to the access side media path of the first session may be represented by SDP1. The call invitation message sent by the ATCF to the IBCF/TrGW is the first call invitation message.

S303. After receiving the first call invitation message, the IBCF/TrGW determines that the transport address is to be converted, and then the SDP1 in the first call invite message is modified into the SDP information corresponding to the remote media path of the first session (SDP2). It should be noted that, if the calling party and the called party are in the IMS network of different operators, after the call invitation message sent by the calling party reaches the IMS network of the called party, the IBCF/TrGW needs to perform the conversion of the transmission address, specifically It is to perform conversion of different IP addresses, ports or versions, etc., and the conversion of the transport address is usually done by modifying the corresponding media parameters in the SDP information. In this embodiment, the SDP corresponding to the remote media path of the modified first session may be represented by SDP2.

S304. The IBCF/TrGW carries the SDP2 in the call invitation message and sends the message to the I/S-CSCF. If the SCC AS and the border gateway include an I/S-CSCF, perform S304; if the SCC AS is directly connected to the border gateway, the border gateway may directly send a call invitation message to the SCC AS. The call invitation message sent by the IBCF/TrGW to the I/S-CSCF is the second call invite message.

S305. The I/S-CSCF sends a call invitation message (with the first session identifier #1) to the SCC AS.

The SCC AS saves the received SDP2 and other session related information.

S306. The SCC AS returns a response message of the call invitation message.

5307. The I/S-CSCF sends a call invitation message (carrying the first session identifier #1) to the UE2.

5308. Each entity performs a subsequent call interaction process to complete call setup, and the media path is divided into two parts: a PS access path and a remote media path by the ATGW.

Among them, multiple border gateways may be connected in the remote media path.

5309. The SRVCC handover occurs in the call, and the MSC server/MGW sends an SRVCC handover request to the ATCF/ATGW.

5310. The ATCF/ATGW returns an SRVCC handover response to the MSC server/MGW, and establishes a circuit-switched CS domain media path with the MSC server/MGW.

S311, the ATCF/ATGW sends an IMS session switch message to the IBCF/TrGW, where the IMS session switch message is used to indicate that the first session is replaced by the second session in the SRVCC handover process, where the IMS session switch message carries the first session. Session ID. The ATCF/ATGW sends an IMS session switch message to the IBCF/TrGW as the first session switch message.

S312: After receiving the IMS session switching message, the IBCF/TrGW searches for the first session according to the session identifier of the first session, and obtains the session description protocol SDP information (SDP2) corresponding to the remote media path of the first session.

S313: The IBCF/TrGW replaces the SDP information (SDP3) corresponding to the access side media path of the second session by using the SDP information corresponding to the remote media path of the first session (SDP2), and sends the information to the I/S in the IMS session switching message. -CSCF. The IMS session switch message sent by the IBCF/TrGW to the I/S-CSCF is the second IMS session switch message.

5314. The I/S-CSCF sends the IMS session switch message carrying the SDP2 to the SCC AS. The IMS session switch message sent by the I/S-CSCF to the SCC AS is also the second IMS session switch message.

S315. The SCC AS maintains the remote media path of the second session as the remote media path of the first session according to the SDP information corresponding to the remote media path of the first session.

After receiving the IMS session switching message, the SCC AS performs the SDP information (SDP2) carried in the IMS session switching message with the SDP information (SDP2) corresponding to the remote media path of the first session (original session) saved by the SCC AS. In the embodiment of the present invention, the SCC information received by the SCC AS in the IMS session switching message is the SDP information corresponding to the remote media path of the first session, so the SCC AS does not need to update the remote media path, thereby avoiding The SRVCC handover interruption caused by updating the remote media path maintains the continuity of user calls during the SRVCC process.

It should be noted that, in this embodiment, a method of maintaining a call continuity is described by taking a calling process as an example, and a part of the entity is omitted. In fact, the method for maintaining call continuity provided by the present invention is also applicable to the called process. There may also be several border gateways that can perform address translation in the calling path of the calling party and the called party.

The method for maintaining the continuation of the call is provided by the border gateway, and the SDP corresponding to the remote media path corresponding to the original session is obtained by the border gateway, and the SDP information is carried in the IMS session switching message and sent to the SCC AS to avoid the SCC. The AS updates the remote media path when the access side media path is updated, thereby maintaining the continuity of the user call during the SRVCC process.

The present invention also provides another feasible embodiment for maintaining the continuity of the call. Specifically, the remote media path of the original session can be maintained in the SRVCC process, thereby preventing the SCC AS from updating the remote media path when the access side media path is updated. Thereby achieving continuity of user calls during the SRVCC process. As shown in Figure 4, it specifically includes:

S401. Receive a single radio voice call continuous SRVCC handover request sent by the mobile switching center MSC server or the media gateway MGW.

S402. Return an SRVCC handover response to the MSC server or the MGW.

S403. Send an access handover message to the border gateway, so that the border gateway forwards the access handover message to the service set and the continuous application server SCC AS, and the access switch message is used to indicate the SRVCC. The remote media path of the first session is maintained during the handover.

The execution entity of the above step is an access switching entity, which may specifically be an ATCF or an ATGW. The border gateway can be IBCF/TrGW or the like.

When the calling party sends a call invitation to the called party, after the two parties complete the call setup, the media path is divided into two parts: the PS access path and the remote media path by the ATGW. When the call occurs SRVCC handover, the MSC server (Server) or the MGW first initiates the media path switch of the access side to the ATCF/ATGW, and the ATCF/ATGW sends the media on the access side after the MSC server or the MGW responds to the media path of the access side. The path is switched from the PS access path to the CS access path.

After the CS access path is established on the access side, the ATCF/ATGW sends an access handover message to the border gateway, the access handover message being used to indicate that the first session is maintained during the SRVCC handover.

After receiving the access handover message, the border gateway may forward the access handover message to the SCC AS through the I/S-CSCF, or directly forward the access handover message to the SCC AS.

In the embodiment of the present invention, the session between the calling party and the called party is not re-established during the SRVCC handover process. Therefore, the SDP information corresponding to the remote media path does not change, and the SCC AS is prevented from updating the remote media path. In turn, the SRVCC handover interruption caused by updating the remote media path is avoided, and the continuity of the user call in the SRVCC process is maintained.

The method for maintaining call continuity in this embodiment maintains the original session in the SRVCC process, so as to prevent the SCC AS from updating the remote media path when the access side media path is updated, thereby maintaining the continuity of the user call during the SRVCC process.

FIG. 5 is a flowchart of still another embodiment of a method for maintaining call continuity according to the present invention, as shown in FIG.

As shown in 5, the method includes:

S501. Receive an access switch message, where the access switch message is used to indicate that the remote media path of the first session is maintained during a continuous radio voice call continuous SRVCC handover process;

5502. Switch the first session from the packet switched PS domain to the circuit switched CS domain according to the access handover message.

The executive body of the above embodiment is an SCC AS.

If the SCC AS and the border gateway (eg, IBCF/TrGW, etc.) further include an IS/CSCF, the border gateway may send an access handover message to the SCC AS through the I/S-CSCF; if the SCC AS is directly connected to the border gateway Then, the border gateway can directly send an access handover message to the SCC AS.

After receiving the access handover message, the SCC AS indicates that the access handover message is in the SRVCC. The remote media path of the first session is maintained during the handover, so the SCC AS can switch the first session from the PS domain to the CS domain.

In the embodiment of the present invention, the SDP information of the remote media path does not change, and the SCC AS does not change the remote media path, and the SCC AS does not change the session during the SRVCC handover process. The SRVCC handover interruption caused by updating the remote media path is avoided, and the continuity of the user call during the SRVCC process is maintained.

The embodiment shown in FIG. 4 and FIG. 5 respectively describes a method for maintaining call continuity provided by the present invention from the access switching entity (ATCF/ATGW) side and the SCC AS side, and the following provides the embodiments provided in FIG. 4 and FIG. The original session establishment process of the calling party and the called party and the complete implementation scenario of the SRVCC handover process. As shown in FIG. 6, in this embodiment, the calling party is represented by UE1, and the called party is represented by UE2. The embodiment specifically includes the following steps:

S601. The ATCF/ATGW receives the call invitation message (INVITE) sent by the UE1.

S602, the ATCF determines that the media path is to be anchored, and the ATCF can process the media resource in the ATGW, generate the SDP information corresponding to the access side media path of the first session (SDP1), and carry the SDP1 in the call invitation message. Give IBCF/TrGW. In S602, the call invitation message sent by the ATCF to the IBCF/TrGW carries the session identifier of the first session. In this embodiment, the session identifier of the first session is represented by SIP INFO #1.

S603: After receiving the call invitation message, the IBCF/TrGW determines that the transfer address is to be changed, and then the SDP1 in the call invitation message is modified into the SDP information corresponding to the remote media path of the first session (SDP2).

S604. The IBCF/TrGW carries the SDP2 in the call invitation message and sends the message to the I/S-CSCF. S605. The I/S-CSCF sends a call invitation message to the SCC AS, and the SCC AS saves the received message.

SDP information and other session related information.

S606. The SCC AS returns a response message of the call invitation message.

5607. The I/S-CSCF sends a call invitation message to UE2.

5608. Each entity performs a subsequent call interaction process to complete call setup, and the media path is divided into two parts: a PS access path and a remote media path by the ATGW. 5609. The SRVCC handover occurs in the call, and the MSC server/MGW sends an SRVCC handover request to the ATCF/ATGW.

5610. The ATCF/ATGW returns an SRVCC handover response to the MSC server/MGW, and establishes a circuit-switched CS domain media path with the MSC server/MGW.

The specific process of the foregoing S601-S610 is similar to that of the S301-S310. For details, refer to related descriptions in S301-S310, and details are not described herein again.

5611. The ATCF/ATGW sends an access handover message to the IBCF/TrGW, where the access handover message is used to indicate that the remote media path of the first session is maintained during the SRVCC handover.

It should be noted that, in some implementation scenarios, UE1 and UE2 may have multiple sessions. In this case, the access handover message may further carry the session identifier, because the ATCF/ATGW sends the connection to the IBCF/TrGW. The inbound switching message indicates that the remote media path of the first session is maintained during the SRVCC handover process. Therefore, the session identifier carried in the access handover message is still the session identifier SIP INFO#1 of the first session, to indicate that the SRVCC needs to be switched. Which session or sessions between UE1 and UE2 are maintained during the process.

S612. The IBCF/TrGW forwards the access handover message to the I/S-CSCF.

S613. The I/S-CSCF forwards the access handover message to the SCC AS.

S614. The SCC AS completes the subsequent handover process in the session according to the access handover message, and switches the first session from the PS domain to the CS domain.

FIG. 4 is a schematic diagram of an embodiment of maintaining a call continuation in the SRVCC process, so as to prevent the SCC AS from updating the remote media path when the access side media path is updated, thereby maintaining the user in the SRVCC process. The continuity of the call. The present invention also provides another feasible embodiment for maintaining call continuity. Specifically, the IMS session switching message may be sent to the border gateway by the access switching entity (ATCF/ATGW) to enable the SCC AS to update the media path on the access side. The remote media path is then updated to maintain the continuity of the user's call during the SRVCC process. As shown in Figure 7, the details include:

S701. Receive a single wireless voice call sent by the mobile switching center MSC server or the MGW. Continuous SRVCC handover request;

S702. Return an SRVCC handover response to the MSC server or the MGW.

S703. After the set time is reached, send an Internet Protocol Multimedia Subsystem IMS session switch request to the SCC AS, where the IMS session switch message is used to replace the first session with the second session in the SRVCC handover process, and the IMS session switch request carries the second session. The SDP information corresponding to the access side media path of the session, so that the SCC AS updates the remote media path of the second session according to the SDP information corresponding to the access side media path of the second session after the access side media path is updated.

When the calling party sends a call invitation to the called party, after the two parties complete the call setup, the media path is

The ATGW is divided into two parts: a PS access path and a remote media path. When the call occurs SRVCC handover, the MSC server (Server) or the MGW first initiates the media path switch of the access side to the ATCF/ATGW, and the ATCF/ATGW sends the media on the access side after the MSC server or the MGW responds to the media path of the access side. The path is switched from the PS access path to the CS access path.

After the access side completes the establishment of the CS access path, the ATCF/ATGW may delay the set time and then send an IMS session switch request to the SCC AS, so that the SCC AS can update the access side media path, and then The SDP information corresponding to the access side media path of the second session updates the remote media path of the second session. Thereby achieving continuity of user calls during the SRVCC process. The time required for the body path switching process is determined, for example, set to 5 seconds, or adjusted as needed.

The IMS session switching message may be used to indicate that the first session is replaced by the second session in the SRVCC handover process, and the IMS session switching request may carry the SDP information corresponding to the access side media path of the second session, that is, the After the time is determined, the process of the IF session switching request sent by the ATCF/ATGW to the SCC AS may be performed by an existing process, and details are not described herein again.

The method for maintaining the continuation of the call provided by the embodiment, the IMS session switching message is sent to the border gateway by the access switching entity, so that the SCC AS updates the remote media path after the access side media path is updated, thereby implementing the SRVCC process. Keep the user's call continuous.

The embodiment shown in FIG. 7 illustrates a method for maintaining call continuity provided by the present invention from an access handover entity. The following provides the original session establishment process of the calling party and the called party in the embodiment provided in FIG. 7. And the complete implementation scenario of the SRVCC handover process. As shown in FIG. 8, in this embodiment, the calling party is represented by UE1, and the called party is represented by UE2. The embodiment specifically includes the following steps:

S801. The ATCF/ATGW receives the call invitation message (INVITE) sent by the UE1.

S802: The ATCF determines that the media path is to be anchored, and the ATCF can process the media resource in the allocated ATGW, generate the SDP information corresponding to the access side media path of the first session (SDP1), and carry the SDP1 in the call invitation message. Give IBCF/TrGW.

S803. After receiving the call invitation message, the IBCF/TrGW determines that the transport address is to be converted, and then the SDP1 in the call invitation message is modified into the SDP information corresponding to the remote media path of the first session (SDP2).

S804. The IBCF/TrGW carries the SDP2 in the call invitation message and sends the message to the I/S-CSCF.

S805. The I/S-CSCF sends a call invitation message to the SCC AS, and the SCC AS saves the received SDP2 and other session related information.

S806. The SCC AS returns a response message of the call invitation message.

S807. The I/S-CSCF sends a call invitation message to UE2.

S808: Each entity performs a subsequent call interaction process to complete call setup, and the media path is divided into two parts: a PS access path and a remote media path by the ATGW.

5809. The call has an SRVCC handover, and the MSC server/MGW sends an SRVCC handover request to the ATCF/ATGW.

5810. The ATCF/ATGW returns an SRVCC handover response to the MSC server/MGW, and establishes a circuit-switched CS domain media path with the MSC server/MGW.

The specific process of the foregoing S801-S810 is similar to that of the S301-S310. For details, refer to related descriptions in S301-S310, and details are not described herein again.

5811. The ATCF/ATGW starts a timer, and sends an IMS session switch to the IBCF/TrGW after the timer expires.

S812. The IBCF/TrGW sends the IMS session switch to the I/S-CSCF.

5813. The I/S-CSCF sends the IMS session switch to the SCC AS.

S814: The SCC information is compared between the SDP information carried in the received IMS session switch and the SDP information corresponding to the remote media path of the first session (original session) saved by the SCC AS. If the comparison result is different, the SCC AS initiates an update of the remote connection media path.

Among them, the process of S812-S814 is similar to the execution process of the prior art, and no further description is performed here. Said.

Since the SCC AS update remote media path is performed after the access side media path is updated, the media interruption caused by the access side media path and the remote media path simultaneously updating the media path is avoided, and the continuous call of the user is maintained during the SRVCC process. .

A person skilled in the art can understand that all or part of the steps of implementing the above method embodiments may be completed by using hardware related to program instructions, and the foregoing program may be stored in a computer readable storage medium, and the program is executed when executed. The foregoing steps include the steps of the foregoing method embodiments; and the foregoing storage medium includes: a medium that can store program codes, such as a ROM, a RAM, a magnetic disk, or an optical disk.

FIG. 9 is a schematic structural diagram of an embodiment of a border gateway according to the present invention. As shown in FIG. 9, the border gateway includes: a receiver 11, a processor 12, and a transmitter 13;

The receiver 11 is configured to receive a first Internet Protocol Multimedia Subsystem IMS Session Switch message sent by the access switching entity, where the first IMS session switch message is used to indicate that the second session is replaced in the continuous SRVCC handover process of the single radio voice call. a session, where the first IMS session switching message carries the session identifier of the first session;

The processor 12 is configured to search for the first session according to the session identifier of the first session, and obtain session description protocol SDP information corresponding to the remote media path of the first session;

The sender 13 is configured to send a second IMS session switch message to the service aggregation and the continuous application server SCC AS, where the second IMS session switch message carries the SDP information corresponding to the remote media path of the first session.

As a possible implementation, the receiver 11 is further configured to: receive the first call invitation information sent by the access switching entity, where the first call invitation information carries the SDP information corresponding to the access side media path of the first session.

Further, the sender 13 may be further configured to: send the second call invitation information to the SCC AS, where the second call invitation information carries the SDP information corresponding to the remote media path of the first session.

The first IMS session switching message sent by the access switching entity received by the receiver 11 may also carry the SDP information corresponding to the access side media path of the second session. Then, the processor 12 may be further configured to: The SDP information corresponding to the remote media path of the second session carried in the first IMS session switching message is replaced by the SDP information corresponding to the access side media path of the first session, and the first IMS session switching message is used as the second IMS session switch message. As a possible implementation, the sender 13 may be specifically configured to: send a second IMS session switch message to the query/service call session control function I/S-CSCF, so that the I/S-CSCF switches the second IMS session. The message is forwarded to the SCC AS.

The border gateway provided by the embodiment of the present invention is an execution device of the method for maintaining call continuity provided by the present invention. For the specific process of performing the method for maintaining call continuity, reference may be made to the method embodiment shown in FIG. 1 to FIG. Let me repeat.

The border gateway provided in this embodiment obtains the SDP corresponding to the remote media path corresponding to the original session according to the original session identifier, and carries the SDP information in the IMS session switch message to the SCC AS to prevent the SCC AS from accessing the media on the access side. The remote media path is updated when the path is updated, thereby maintaining the continuity of the user's call during the SRVCC process.

FIG. 10 is a schematic structural diagram of an embodiment of a service centralized and continuous application server according to the present invention. As shown in FIG. 10, the SCC AS includes: a receiver 21 and a processor 22;

The receiver 21 is configured to receive a second Internet Protocol Multimedia Subsystem IMS Session Switch message, where the second IMS Session Switch message is used to indicate that the second session is used to replace the first session, and the second IMS is used in a single radio voice call continuous SRVCC handover process. The session switching message carries the SDP information corresponding to the remote media path of the first session;

The processor 22 is configured to maintain the remote media path of the second session as the remote media path of the first session according to the SDP information corresponding to the remote media path of the first session.

The SCC AS provided by the embodiment of the present invention is an execution device of the method for maintaining call continuity provided by the present invention. For the specific process of performing the method for maintaining call continuity, reference may be made to the method embodiment shown in FIG. 1 to FIG. Let me repeat.

In the SCC AS provided by the embodiment, the border gateway obtains the SDP information corresponding to the remote media path of the original session according to the original session identifier, and carries the SDP information in the IMS session switch message to the SCC AS, and the SCC AS receives the IMS session. After the message is switched, the SDP information carried in the IMS session switching message is compared with the SDP information corresponding to the remote media path of the original session. If the comparison result is the same, the SCC AS does not need to update the remote media path, so as to prevent the SCC AS from being connected. The remote media path is updated when the inbound media path is updated, so as to maintain the continuity of the user call during the SRVCC process.

FIG. 11 is a schematic structural diagram of an embodiment of an access switching entity according to the present invention. As shown in FIG. 11, the access switching entity includes: a receiver 31 and a transmitter 32; The receiver 31 is configured to receive a single radio voice call continuous SRVCC handover request sent by the mobile switching center MSC server or the media gateway MGW;

The transmitter 32 is configured to send an SRVCC handover response to the MSC server or the MGW, and is further configured to send an access handover message to the border gateway, so that the border gateway forwards the access handover message to the service set and the continuous application server SCC AS, and accesses The handover message is used to indicate that the remote media path of the first session is maintained during the SRVCC handover.

The access switching entity provided by the embodiment of the present invention may specifically be an execution device of the method for maintaining a call continuity provided by the ATCF/ATGW, and the specific process for performing the method for maintaining the call continuity may be as shown in FIG. 4-6. The method embodiment is not described here.

The access switching entity provided in this embodiment indicates that the SCC AS maintains the original session in the SRVCC process, so as to prevent the SCC AS from updating the remote media path when the access side media path is updated, thereby maintaining the continuous call of the user during the SRVCC process. .

FIG. 12 is a schematic structural diagram of another embodiment of a service centralized and continuous application server according to the present invention. As shown in FIG. 12, the SCC AS may include: a receiver 41 and a processor 42; wherein: a receiver 41 is configured to receive Accessing a handover message, the access handover message is used to indicate that the remote media path of the first session is maintained during a continuous voice VPC handover of the single wireless voice call;

The processor 42 is configured to switch the first session from the packet switched PS domain to the circuit switched CS domain according to the access handover message.

The SCC AS provided by the embodiment of the present invention is an execution device of the method for maintaining call continuity provided by the present invention. For the specific process of performing the method for maintaining call continuity, reference may be made to the method embodiment shown in FIG. 4 to FIG. Let me repeat.

The SCC AS provided in this embodiment keeps the original session according to the indication of the access handover control function in the SRVCC process, so as to prevent the SCC AS from updating the remote media path when the access side media path is updated, thereby maintaining the user in the SRVCC process. The continuity of the call.

FIG. 13 is a schematic structural diagram of still another embodiment of an access switching entity according to the present invention, as shown in FIG.

As shown in FIG. 13, the access switching control function includes: a receiver 51 and a transmitter 52; wherein:

The receiver 51 is configured to receive a single radio voice call continuous SRVCC handover request sent by the mobile switching center MSC server or the media gateway MGW;

The transmitter 52 is configured to return an SRVCC handover response to the MSC server or the MGW, and is further configured to send an Internet protocol to the service set and the continuous application server SCC AS after the set time is reached. The media subsystem IMS session switching request is used to indicate that the first session is replaced by the second session in the SRVCC handover process, and the IMS session switching message carries the SDP information corresponding to the access side media path of the second session, After the SCC AS updates the access side media path, the remote media path of the second session is updated according to the SDP information corresponding to the access side media path of the second session.

FIG. 14 is a schematic structural diagram of another embodiment of an access switching entity according to the present invention. As shown in FIG. 14, the access switching entity may further include:

The timer 53 can be used to start the time after the transmitter 52 returns the SRVCC handover response to the MSC server or the MGW, and after the set time is reached, the trigger sender sends an Internet Protocol Multimedia Subsystem IMS session handover request to the SCC AS.

The access switching entity provided by the embodiment of the present invention may specifically be an execution device of the method for maintaining call continuity provided by the ATCF/ATGW, and the specific process for performing the method for maintaining call continuity may be as shown in FIG. 7 and FIG. 8. The method embodiment is not described here.

The access switching entity provided in this embodiment sends an IMS session switching message to the border gateway by delaying, so that the SCC AS updates the remote media path after the access side media path is updated, thereby maintaining the continuity of the user call in the SRVCC process. .

It should be noted that the above embodiments are only for explaining the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: The technical solutions described in the foregoing embodiments are modified, or some of the technical features are equivalently replaced. The modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

Rights request

A method for maintaining call continuity, characterized in that it comprises:

Receiving, by the access switching entity, a first Internet Protocol multimedia subsystem IMS session switching message, where the first IMS session switching message is used to indicate that the second session is used to replace the first session in a single wireless voice call continuous SRVCC handover process. Carrying the session identifier of the first session in the first IMS session switching message;

The method according to claim 1, wherein before receiving the first Internet Protocol Multimedia Subsystem IMS session switching message sent by the access switching entity, the method further includes:

Receiving the first call invitation information sent by the access switch entity, where the first call invitation information carries the SDP information corresponding to the access side media path of the first session.

The method according to claim 2, wherein before receiving the first Internet Protocol Multimedia Subsystem IMS session switching message sent by the access switching entity, the method further includes:

The second call invitation information is sent to the SCC AS, where the second call invitation information carries SDP information corresponding to the remote media path of the first session.

The method according to any one of claims 1-3, wherein the first IMS session switching message sent by the access switching entity further carries an access side media path corresponding to the second session. SDP information;

Before the sending the second IMS session switching message to the service centralized and continuous application server SCC AS, the method further includes:

After the SDP information corresponding to the remote media path of the second session that is carried in the first IMS session switching message is replaced by the SDP information corresponding to the access side media path of the first session, the first The IMS session switch message is used as the second IMS session switch message.

The method according to any one of claims 1-4, wherein the sending, by the service aggregation and the continuous application server SCC AS, a second IMS session switching message is specifically:

Transmitting the second IMS session switch to the query/service call session control function I/S-CSCF And causing the I/S-CSCF to forward the second IMS session handover message to the SCC AS.

6. A method for maintaining call continuity, characterized in that it comprises:

Receiving a single radio voice call sent by the mobile switching center MSC server or media gateway MGW, a continuous SRVCC handover request;

Returning an SRVCC handover response to the MSC server or the MGW;

7. A method for maintaining call continuity, characterized in that it comprises:

Returning an SRVCC handover response to the MSC server or the MGW;

8. A border gateway, comprising:

a receiver, configured to receive a first Internet Protocol multimedia subsystem sent by an access switching entity

The IMS session switching message, the first IMS session switching message is used to indicate that the first session is replaced by the second session in the continuous SRVCC handover process of the single radio voice call, and the first IMS session switching message carries the first session Session identifier;

The border gateway according to claim 8, wherein the receiver is further configured to: receive the first call invitation information sent by the access switch entity, where the first call invitation information is And carrying the SDP information corresponding to the access side media path of the first session.

The border gateway according to claim 9, wherein the transmitter is further configured to: send a second call invitation information to the SCC AS, where the second call invitation information carries the first session The SDP information corresponding to the remote media path.

The border gateway according to any one of claims 8 to 10, wherein the first IMS session switching message sent by the access switching entity received by the receiver further carries the second session. SDP information corresponding to the access side media path;

The processor is further configured to: use the SDP information corresponding to the remote media path of the second session that is carried in the first IMS session switching message by using the SDP information corresponding to the access side media path of the first session. After the replacement, the first IMS session switching message is used as the second IMS session switching message.

The border gateway according to any one of claims 8-11, wherein the transmitter is specifically configured to: send the second IMS session switch to a query/service call session control function I/S-CSCF a message, to cause the I/S-CSCF to forward the second IMS session switch message to the SCC AS.

13. An access switching entity, comprising:

a transmitter, configured to send an SRVCC handover response to the MSC server or the MGW, and configured to send an access handover message to the border gateway, so that the border gateway forwards the access handover message to the service centralized and continuous application server The SCC AS, the access handover message is used to indicate that the remote media path of the first session is maintained during the SRVCC handover process.

14. An access switching entity, comprising:

a transmitter, configured to return an SRVCC handover response to the MSC server or the MGW; and configured to send an Internet Protocol Multimedia Subsystem IMS session handover request to the service set and the continuous application server SCC AS after the set time is reached, where the IMS session The switching message is used to indicate that the first session is replaced by the second session in the SRVCC handover process, where the IMS session switching message carries the SDP information corresponding to the access side media path of the second session, so that the SCC AS is in the Access side media After the volume path is updated, the remote media path of the second session is updated according to the SDP information corresponding to the access side media path of the second session.

The access switching entity according to claim 14, further comprising: a timer, configured to start in time after the transmitter returns an SRVCC handover response to the MSC server or the MGW, and after reaching the After the time is set, the sender is triggered to send an Internet Protocol Multimedia Subsystem IMS session switch request to the SCC AS.