CN101370176B - Method and device for transferring multimedia conversation between different access networks - Google Patents

Abstract

The invention proposes a method and device for transferring multimedia sessions between different access networks. Wherein, the method includes: the application server (AS) learns that the multimedia session of the user equipment (UE) will be transferred to multiple access networks, the AS receives multiple transfer request messages sent by the UE, and transfers the media information in the transfer request message to Integration is performed, and the integrated media information is sent to the peer UE. The method and device proposed by the present invention can shorten the transfer time and reduce operation redundancy when the UE's multimedia session is transferred to multiple access networks.

Description

Method and device for transferring multimedia session between different access networks

technical field

The invention relates to the technical field of mobile communication, in particular to a method and a device for transferring a multimedia session between different access networks. the

Background technique

When the multimedia user equipment (UE, User Equipment) is transferred between different access networks, it needs to ensure that the originally established session will not be interrupted during the transfer process. Voice Call Continuity (VCC, Voice Call Continuity) technology provides domain transfer capability of voice between Circuit Switched (CS, Circuit Switched) domain and IP Multimedia Subsystem (IMS, IP Multimedia Subsystem) domain. The core device of the VCC technology is the VCC voice call continuity application server (VCC AS, VCC Application Server), which completes the domain transfer function between the CS domain call branch and the IMS domain call branch. All user calls or sessions must pass through the VCC AS in the IMS domain, and the VCC AS is ready for subsequent transfer control. This process is called IMS anchoring (Anchoring in IMS). the

When the UE in the talking state detects a change in the surrounding wireless environment or other changes, it will transfer according to a predefined transfer strategy. The UE initiates a domain transfer request from the domain to be transferred to the VCC AS, and the VCC AS establishes a connection with the UE in the transferred domain, transfers the session connection of the peer UE to the new connection, and releases the session of the transferred domain at the same time connect. the

The VCC Domain Transfer Number (VDN, VCC Domain Transfer URI) and the VCC Domain Transfer Universal Resource Identifier (VDI, VCC Domain Transfer Number) are identifiers used to indicate that domain transfer needs to be initiated, and are stored in the UE at the same time. When the UE wants to switch to the CS domain network, it initiates a call with the VDN as the called number; when the UE wants to switch to the PS domain network, it initiates the call with the VDI as the called number, and the VCC AS judges that the call is a Domain transfer request message. the

With the continuous development of the network, users' services are not limited to voice, but also develop in diversified directions such as video and file transmission. The following is a typical example in the prior art where the UE in the process of multi-path session transfers. Referring to FIG. 1 , FIG. 1 is a flow chart of implementing transfer according to the practice of the existing VCC technology. the

It is assumed that UE-1 has three media streams in the World Interoperability Coordination Organization for Microwave Access (WIMAX) network, namely, voice (Voice), video (Video), and file (Text), which are transmitted in the PS network. Now when it is necessary to transfer to the Universal Mobile Telecommunications System (UMTS) network, it is assumed that the voice media stream will be transferred to the UMTS circuit switching (CS) domain network, and the other two media streams will be transferred to the UMTS packet switching (PS, Packet Switched) domain network. According to the traditional VCC method, perform the following steps. the

Step 101: UE-1 initiates a call on the UMTS CS domain network using the VDN as the called number, and the VDN is used to identify the call as a transfer request message. Specifically: send a Setup (Setup) message to a Visit Mobile Switching Center (VMSC, Visit Mobile Switching Center), and the VMSC sends the message to a Media Gateway Control Function (MGCF, MGW Control Function) entity. the

Step 102: MGCF performs protocol conversion, converts CS domain signaling into Invite message, and media information (i.e. port number, IP address, etc. of MGW) of media gateway (MGW, Media Gateway) and media row information of Voice (i.e. m=Voice) writes the invitation (Invite) message, and sends the Invite message to the VCC AS. the

Step 103: VCC AS initiates a re-Invite (re-Invite)/Update (Update) message to UE-2 according to the anchor information, and the message carries the media information of the media gateway (MGW) and the media line information of Voice, and notifies the UE -2 Update media information. the

Step 104: UE-2 returns a 200 OK confirmation message to the VCC AS, which carries the media information of UE-2 (ie, the IP address and port number of UE-2). the

Step 105: The VCC AS sends the 200 OK confirmation message to the MGCF; the MGCF performs protocol conversion, converts the 200 OK message into a connection (Connect) message, and sends it to UE-1. the

Step 106: UE-1 initiates a call on the UMTS PS domain network using the VDI as the called number, and the VDI is used to identify the call as a transfer request message. Specifically: send the Invite message to the VCC AS, which carries the media information of UE-1 (i.e. the port number and IP address of UE-1) and the media row information of Video and Text (i.e. m=Video; m=Text) . the

Step 107: VCC AS initiates a re-Invite/Update message to UE-2 according to the anchor information, the message carries the media information of UE-1 and the media line information of Video and Text, and notifies UE-2 to update the media information. the

Step 108: UE-2 returns a 200 OK confirmation message to UE-1, which carries the media information of UE-2. the

In the above process, steps 101 to 105 are used to complete the session connection between UE-1 and UE-2 in the CS domain; steps 106 to 108 are used to complete the session connection between UE-1 and UE-2 in the PS domain. As for step 103 and step 107, it can be seen that the functions of the two steps are similar, both of which are to notify UE-2 to update the media information, and completing two steps separately will constitute operational redundancy. And, due to the characteristic that the re-Invite/Update message itself cannot be carried out at the same time, the second re-Invite/Update message can only be initiated after the confirmation message 200 OK of the first re-Invite/Update message arrives, which increases the The transfer time of UE-1 may cause the second transfer request to fail. It can be seen that when a multimedia session is transferred between different access networks, there will be problems such as operation redundancy and long transfer time. the

Contents of the invention

In view of this, an embodiment of the present invention proposes a method for transferring a multimedia session between different access networks, which can shorten the transfer time and reduce operational redundancy when the multimedia session of the UE is transferred to multiple access networks. the

The embodiment of the present invention also proposes an AS, which can shorten the transfer time and reduce operation redundancy when the UE's multimedia session is transferred to multiple access networks. the

The embodiment of the present invention also proposes a UE, which can shorten the transfer time and reduce operation redundancy when the multimedia session is transferred to multiple access networks. the

In order to achieve the above object, technical scheme of the present invention is achieved in that:

A method for transferring a multimedia session between different access networks, the method comprising:

The AS learns that the UE's multimedia session will be transferred to the circuit-switched CS domain and the packet-switched PS domain of the Universal Mobile Telecommunications System UMTS network, and the AS receives multiple transfer request messages sent by the UE, and transfers the media information in the multiple transfer request messages Integrating, sending the integrated media information to the peer UE. the

An AS, the AS includes:

The first access network transfer information receiving module is configured to receive the access network transfer information sent by the UE, and the access network transfer information is used to let the AS know that the multimedia session of the UE needs to transfer to the circuit switched CS of the universal mobile communication system UMTS network domain and packet exchange PS domain for transfer;

A transfer request message receiving module, configured to receive multiple transfer request messages sent by the UE;

The media information integration module is configured to integrate the media information in the multiple transfer request messages received, and send the integrated media information to the peer UE. the

A kind of AS, it is characterized in that, this AS comprises:

Access network transfer information acquisition module, used to obtain UE access network transfer information;

The second access network transfer information sending module is used to send access network transfer information to the UE;

The access network transfer information is used to make the AS know that the multimedia session of the UE needs to be transferred to the circuit switched CS domain and the packet switched PS domain of the Universal Mobile Telecommunications System UMTS network;

A transfer request message receiving module, configured to receive multiple transfer request messages sent by the UE;

The media information integration module is configured to integrate the media information in the multiple transfer request messages received, and send the integrated media information to the peer UE. the

A UE, the UE includes: a transfer request message sending module, configured to send a transfer request message to an AS; a first access network transfer information sending module, configured to send access network transfer information to an AS, the access network transfer information The information is used to let the AS know that the multimedia session of the UE needs to be transferred to the circuit switching CS domain and the packet switching PS domain of the Universal Mobile Telecommunications System UMTS network. the

It can be seen that the method, AS and UE proposed in the embodiment of the present invention integrate the media information in the transfer request message, carry the integrated media information in an update message and send it to the peer UE; When a transfer request message is received, an update message is sent to the peer UE, thereby solving the problems of operation redundancy and long transfer time in the prior art when the UE's multimedia session is transferred to multiple access networks at the same time. the

Description of drawings

Figure 1 is a flow chart of implementing the transfer according to the existing VCC technology;

Fig. 2 is a flow chart of embodiment 1 that MMSC AS of the present invention learns access network transfer information;

Fig. 3 is the flow chart of Embodiment 2 of the MMSC AS of the present invention knowing the transfer information of the access network;

Fig. 4 is the embodiment three flow charts that MMSC AS of the present invention learns access network transfer information;

Fig. 5 is the flow chart of Embodiment 4 of the MMSC AS of the present invention knowing the transfer information of the access network;

FIG. 6 is a flow chart of implementation of transfer in an embodiment of the present invention. the

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. the

Assume that UE-1 is currently in the WIMAX network and is conducting a session with the peer UE, ie, UE-2, and the session includes three media streams, namely voice, video and file transmission. When UE-1 is about to enter the UMTS network, UE-1 needs to transfer voice media streams to the CS domain of the UMTS network, and transfer video and file media streams to the PS domain of the UMTS network. At this time, the AS performing the transfer is called a Multimedia Session Continuity (MMSC, Multimedia Session Continuity) AS. the

In the above scenario, the method for transferring a multimedia session between different access networks in the embodiment of the present invention includes: the MMSCAS learns that the multimedia session of UE-1 is to be transferred to multiple access networks, and the MMSC AS receives the transfer request sent by UE-1 , integrating the media information of the transfer request and sending it to UE-2. the

In the above method, the integrating may specifically include: integrating the media information in multiple transfer request messages according to the sequence of media lines of the multimedia session. the

In the above method, the prerequisite for integrating the two transfer request messages is that the MMSC AS must first know that UE-1 is transferring to the two access networks. The method of learning can be that the UE-1 that initiates the transfer notifies the MMSC AS of the access network transfer information, and the MMSC AS returns an acknowledgment or rejection response to UE-1. The access network transfer information sent by UE-1 to the MMSC AS may include: at least one of the type of each target access network to be transferred by UE-1 and the number of target access networks;

Alternatively, the MMSC AS can also obtain the access network transfer information through the judgment of UE-1's location information or other third-party trigger information, and notify UE-1 after learning, and UE-1 returns an acknowledgment or rejection response to the MMSC AS. The access network transfer information sent by the MMSC AS to UE-1 may include: the type of the target access network that the UE will transfer to. the

Wherein, each of the above two learning methods has two different ways. The manners of obtaining the transfer information of the access network are respectively described below. the

Referring to FIG. 2, FIG. 2 is a flow chart of Embodiment 1 of the present invention in which the MSC AS obtains access network transfer information. In Embodiment 1, UE-1 may carry the access network transfer information in an intra-session message and transmit it to the MMSC AS. The target access network where the UE is located after performing the handover performs transmission. Wherein, the intra-session message includes a re-Invite message, an Update message, or an Info message, etc., which are carried in the re-Invite message as an example below. the

Step 201: UE-1 defines an access network transfer information indication (DTReq=PS/CS), which is used to indicate that UE-1 needs to perform transfer in PS domain and CS domain at the same time. UE-1 carries DTReq=PS/CS in the re-Invite message and sends it to the MMSC AS. the

The specific carrying method can be:

Carried by the From header field, that is, add DTReq=PS/CS in the From header field; or,

Carried by the Contact header field, that is, add DTReq=PS/CS in the Contact header field; or,

Carried through the SDP message body, that is, adding the session-level a line in the SDP message body: a=DTReq:<PS/CS>

Step 202: The MMSC AS sends a 200OK message to UE-1, carrying the transfer type it supports. If the MMSC AS accepts the UE-1 request, it will return the indication information intact; if it does not accept it, it will return the transfer type it supports. the

Referring to FIG. 3, FIG. 3 is a flow chart of Embodiment 2 in which the MMSC AS obtains access network transfer information according to the present invention. In the second embodiment, UE-1 may carry the access network transfer information in an out-of-session message and transmit it to the MMSC AS. The target access network where the UE is located after performing the handover performs transmission. Wherein, the out-of-session message includes a notification (Notify) message, or a message (Message) message, etc., which are carried in the Notify message as an example below. the

Step 301: UE-1 defines an access network transfer information request event (DTReq-Event), which is used to indicate that UE-1 needs to perform transfer in PS domain and CS domain at the same time. UE-1 carries the DTReq-Event in the Notify message and sends it to the MMSCAS. the

Step 302: The MMSC AS returns a transfer request confirmation event (DTConf-Event) to UE-1, indicating the transfer type it supports, carries the DTConf-Event in the Notify message, and sends it to UE-1. You can also use the Notify mechanism of SIP to define a new DTConf-Event. the

The two methods shown in Figure 2 and Figure 3 are to notify the MMSC AS of the access network transfer information through the UE-1. The following describes how the MMSC AS itself obtains the access network transfer information and notifies UE-1. the

Referring to Fig. 4, Fig. 4 is the flow chart of Embodiment 3 in which the MMSC AS of the present invention acquires access network transfer information. In Embodiment 3, after the MMSC AS learns the access network transfer information, it can carry the access network transfer information in an intra-session message and transmit it to UE-1. The transmission is performed in the network, or may be performed in the target access network where the UE-1 is located after the handover. Wherein, the intra-session message includes a re-Invite message, an Update message, or an Info message, etc., which are carried in the re-Invite message as an example below. the

Step 401: The MMSC AS defines an access network transfer information indication (DTReq=PS/CS), which is used to indicate that UE-1 needs to perform transfer in both the PS domain and the CS domain. The MMSC AS carries DTReq=PS/CS in the re-Invite message and sends it to UE-1. the

The specific carrying method can be:

Carried by the From header field, that is, add DTReq=PS/CS in the From header field; or,

Carried by the Contact header field, that is, add DTReq=PS/CS in the Contact header field; or,

Carried through the SDP message body, that is, adding the session-level a line in the SDP message body: a=DTReq:<PS/CS>

Step 402: UE-1 sends a 200 OK message to the MMSC AS, carrying the transfer type it supports. If UE-1 accepts the MMSC AS request, it will return the indication information intact; if it does not accept it, it will return the transfer type it supports. the

Referring to FIG. 5, FIG. 5 is a flow chart of Embodiment 4 for the MMSC AS of the present invention to obtain access network transfer information. In Embodiment 4, after the MMSC AS learns the access network transfer information, it can carry the access network transfer information in an out-of-session message and transmit it to UE-1. The transmission is performed in the network, or may be performed in the target access network where the UE-1 is located after the handover. Wherein, the out-of-session message includes a Notify message, or a Message message, etc., which are carried in the Notify message as an example below. the

Step 501: The MMSC AS defines an access network transfer information request event (DTReq-Event), which is used to indicate that UE-1 needs to perform transfer in both the PS domain and the CS domain. UE-1 carries the DTReq-Event in the Notify message and sends it to UE-1. the

Step 502: UE-1 returns a transfer request confirmation event (DTConf-Event) to the MMSC AS, indicating the transfer type it supports, carries the DTConf-Event in the Notify message, and sends it to the MMSC AS. You can also use the Notify mechanism of SIP to define a new DTConf-Event. the

In the flow shown in Fig. 4 and Fig. 5, the MMSC AS can obtain the access network transfer information by judging the location information of UE-1 or other third-party trigger information. Therefore, the two methods shown in Fig. 4 and Fig. 5 can realize that the MMSC AS initiates transfer according to the judgment of UE-1's location information or a third-party trigger condition, while in the prior art, only UE-1 initiates transfer actively. the

Through the above steps in Figure 2, 3, 4 or 5, the MMSC AS knows that UE-1 needs to transfer to two access networks. Integrate the media information in and send the integrated media information to UE-2. Referring to FIG. 6 , FIG. 6 is a flow chart of implementing transfer in an embodiment of the present invention, and the steps described in the flow chart are performed on the premise that the above steps in FIG. 2 , 3 , 4 or 5 have been completed. the

Step 601: UE-1 initiates a call on the UMTS CS domain network using the VDN as the called number, and the VDN identifies the call as a transfer request message. Specifically: send a Setup message to the VMSC, and the VMSC sends the message to the MGCF. the

Step 602: MGCF performs protocol conversion, converts CS domain signaling into an Invite message, and writes MGW media information (ie MGW port number, IP address, etc.) and Voice media line information (ie m=Voice) into the Invite message, send the Invite message to the MMSC AS. the

Step 603: UE-1 initiates a call on the UMTS PS domain network using the VDI as the called number, and the VDI identifies the call as a transfer request message. Specifically: send to MMSC AS, carry the media information of UE-1 (being the port number and IP address of UE-1) and the media row information of Video, Text (being m=Video; m=Text) in this message. the

Step 603 may occur simultaneously with step 601 and step 602, or may occur before step 601 and step 602. the

Step 604: After receiving the transfer request from the CS domain and the PS domain, the MMSC AS integrates the media line information in the two Invite messages, and adjusts the order of the media lines to be the same as the order of the media lines when the session is established. If it is assumed that when establishing a session, the media line information contained in the Invite sent by UE-1 to UE-2 is m=Voice; m=Video; m=Text, then the integrated media line order is: m=Voice; m = Video; m = Text. According to the sequence of the integrated media lines, the media information in the transfer request message is integrated, that is, the integrated media information includes the media information of the MGW and the media information of the UE-1. Carry the integrated media information in the re-Invite/Update message and send it to UE-2. the

Step 605: UE-2 returns a 200 OK confirmation message to the MMSC AS, which carries the media information of UE-2. The MMSC AS generates two 200 OK confirmation messages according to the media line information in the 200 OK confirmation message. According to the media row information, confirm which access network the generated two-way 200 OK confirmation messages are to be sent to respectively. the

Step 606-Step 607: The MMSC AS sends a Connect message to the CS domain of UE-1. the

Step 608: The MMSC AS sends a 200 OK confirmation message to the PS domain of UE-1. the

In the above process, the difference from the prior art is that in step 602, after the MMSC AS receives the transfer request message, it does not immediately send the media information carried in the transfer request message in the re-Invite/Update message to UE-2; instead, after receiving the second transfer request message, integrate the media information in the two messages, carry the integrated media information in the re-Invite/Update message, and send it to UE-2. The beneficial effect brought by the above improvements is that two re-Invite/Update messages with similar functions in the prior art are combined and sent, avoiding signaling waste and operational redundancy caused by sending them twice. the

In addition, in order to prevent the MMSC AS from waiting too long for the transfer request message, the waiting time can be preset. When the interval between two transfer request messages exceeds the preset waiting time, the MMSC AS will no longer wait for the transfer request that has not yet arrived. MMSC AS only processes transfer request messages that arrive within the specified time. The waiting time can be calculated from any moment between when the MMSC AS learns that the multimedia session of UE-1 will be transferred to when the MMSC AS receives the first transfer request message, including the MMSC AS knowing that the multimedia session of UE-1 needs to be transferred. The moment when the transfer is performed, and the moment when the MMSC AS receives the first transfer request message. The specific implementation method can be:

Set the timer in the MMSC AS. After the MMSC AS receives the Invite message in the above step 602, the timer starts counting. If the timer reaches the preset waiting time, the MMSC AS still has not received the UE-1 transmission in the step 603. Invite message, then no longer wait for the message, but only process the Invite message received in step 602. Of course, if step 603 is performed before step 601, the timer starts counting from the moment when the MMSCAS in step 603 receives the Invite message. the

In addition to the above-mentioned methods, there are many ways of timing, such as:

Before the MMSC AS receives the transfer request, when UE-1 notifies the MMSC AS of the access network transfer information shown in Figure 2 or Figure 3, the timing can be started when the notification message of UE-1 arrives at the MMSCAS, or can The timer starts after the MMSC AS responds to UE-1's notification message. the

When the MMSC AS notifies UE-1 of the access network transfer information as shown in Figure 4 or Figure 5 before the MMSC AS receives the transfer request, the timing can be started when the MMSC AS sends the notification message, or the UE-1 can -1 Start timing after the response is returned. the

In a word, the way of timing can be chosen flexibly, and its purpose is to prevent MMSC AS from waiting indefinitely for the arrival of two transfer request messages. the

It is worth noting that the above embodiment is described by taking UE-1's multimedia session to be transferred to two access networks as an example, and the present invention is also applicable to UE-1's multimedia session to be transferred to multiple access networks. Case. When the multimedia session of UE-1 is to be transferred to multiple access networks, the AS learns the transfer information of the access network, waits for the arrival of multiple transfer request messages, integrates the media information in all the received transfer information, and Send the integrated media information to the peer UE. In this case, the waiting time can also be set in advance, so as to prevent the AS from waiting too long for the transfer request message. When the waiting time is over and the transfer request has not yet reached the AS, the AS only processes the received transfer request message, and does not process the time-out transfer request message any more. the

The embodiment of the present invention also proposes an AS, which includes:

The transfer request message receiving module is used to receive the transfer request message sent by the UE;

The media information integration module is configured to integrate the media information in the received transfer request message, and send the integrated media information to the peer UE. the

In the above AS, the media information integration module may be specifically configured to integrate the media information in the transfer request message according to the sequence of media lines in the multimedia session, and send the integrated media information to the peer UE. the

The above AS may further include:

The first access network transfer information receiving module is configured to receive the access network transfer information sent by the UE. the

or further include:

Access network transfer information acquisition module, used to obtain UE access network transfer information;

The second access network transfer information sending module is configured to send access network transfer information to the UE. the

The above AS may further include:

The timer is used to record the waiting time for the transfer request message, and when the recorded waiting time exceeds the preset waiting time, notify the media information integration module not to integrate the timed-out transfer request message. the

This embodiment also proposes a UE, which includes: a transfer request message sending module, configured to send a transfer request message to an AS; a first access network transfer information sending module, configured to send access network transfer information to an AS, so that The access network transfer information is used to let the AS know that the multimedia session of the UE needs to be transferred to multiple access networks. ;

The aforementioned UE may further include: a second access network transfer information receiving module, configured to receive the access network transfer information sent by the AS. the

To sum up, the method for transferring a multimedia session between different access networks proposed by the embodiment of the present invention, the AS and the UE, after learning that the multimedia session of the UE needs to be transferred to multiple access networks, the AS waits for receiving multiple transfer request messages , and integrate the media information in the transfer request message, carry the integrated media information in an update message and send it to the peer UE. This method solves the problems of operation redundancy and long transfer time in the prior art when the UE's multimedia session is transferred to multiple access networks at the same time. Moreover, the embodiment of the present invention also supports the AS to actively initiate the transfer, and the AS may notify the UE to perform the transfer by judging the location information of the UE or other third-party trigger information. In addition, in order to prevent the AS from waiting too long to receive the transfer request message, the present invention can set the waiting time, and when the time exceeds, the AS will no longer process the transfer request message that arrives overtime. the

In summary, the above is only a demonstration of the spirit of the present invention, and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. the

Claims (22)

1. A method for transferring a multimedia session between different access networks, characterized in that the method comprises: The application server AS learns that the multimedia session of the user equipment UE needs to be transferred to the circuit-switched CS domain and the packet-switched PS domain of the Universal Mobile Telecommunications System UMTS network, and the AS receives multiple transfer request messages sent by the UE, and transfers the multiple transfer request messages The integrated media information is integrated, and the integrated media information is sent to the peer UE. 2. The method according to claim 1, wherein said integrating the media information in the multiple transfer request messages specifically comprises: The media information in the multiple transfer request messages is integrated according to the sequence of the media lines of the multimedia session. 3. The method according to claim 1, wherein the step of knowing comprises: The UE sends access network transfer information to the AS, and the AS learns according to the received access network transfer information; The access network transfer information includes: at least one of the type of each target domain to be transferred by the UE and the number of target domains. 4. The method according to claim 1, wherein the obtaining step comprises: the AS judges the UE location information and obtains it according to the judgment result; or the AS obtains it from third-party trigger information. 5. The method according to claim 4, further comprising: after the learning and before the receiving, the AS sends access network transfer information to the UE, and the access network transfer information includes The type of domain to which the transfer is made. The method according to claim 3 or 5, wherein the sending of the access network transfer information is performed in the original access network where the UE is located before the transfer, or in the target domain where the UE is located after the transfer. 7. The method according to claim 3 or 5, wherein the access network transfer information is carried in an intra-session message. 8. The method according to claim 7, wherein the intra-session message comprises: a re-Invite message, an Update message or an Info message. 9. The method according to claim 7, the manner in which the access network transfer information is carried in the intra-session message comprises: The access network transfer information is carried in the header parameter of the intra-session message or in the SDP message body of the intra-session message. 10. The method according to claim 3 or 5, wherein the access network transfer information is carried in an out-of-session message. 11. The method according to claim 10, wherein the out-of-session message comprises: a Notify message or a Message message. 12. The method according to claim 1, further comprising: pre-setting the waiting time of the transfer request message; The AS receiving the transfer request message sent by the UE includes: receiving the transfer request message within the preset waiting time. 13. The method according to claim 12, wherein the waiting time is calculated from any time between when the AS learns that the multimedia session of the UE is to be transferred and when the AS receives the first transfer request message. 14. The method according to claim 1, wherein after the AS sends the integrated media information to the peer UE, further comprising: The peer UE returns an acknowledgment message to the AS, and the AS generates a multi-channel acknowledgment message according to the media line information contained in the acknowledgment message, and sends the generated multiple acknowledgment messages to the circuit-switched CS of the Universal Mobile Telecommunications System UMTS network respectively. domain and packet exchange PS domain is sent to UE. 15. An application server AS, characterized in that the AS comprises: The first access network transfer information receiving module is configured to receive the access network transfer information sent by the user equipment UE, and the access network transfer information is used to let the AS know that the multimedia session of the UE needs to transfer to a circuit of the Universal Mobile Telecommunications System UMTS network Exchange CS domain and packet exchange PS domain for transfer; A transfer request message receiving module, configured to receive multiple transfer request messages sent by the UE; The media information integration module is configured to integrate the media information in the multiple transfer request messages received, and send the integrated media information to the peer UE. 16. The AS according to claim 15, wherein the media information integration module is configured to integrate the media information in multiple transfer request messages according to the media line order of the multimedia session, and integrate the integrated The media information is sent to the peer UE. 17. The AS according to claim 15, wherein the AS further comprises: The timer is used to record the waiting time for the transfer request message, and when the recorded waiting time exceeds the preset waiting time, notify the media information integration module not to integrate the timed-out transfer request message. 18. An application server AS, characterized in that the AS comprises: An access network transfer information acquisition module, configured to obtain access network transfer information of the user equipment UE; A second access network transfer information sending module, configured to send access network transfer information to the UE; The access network transfer information is used to make the AS know that the multimedia session of the UE needs to be transferred to the circuit switching CS domain and the packet switching PS domain of the Universal Mobile Telecommunications System UMTS network; A transfer request message receiving module, configured to receive multiple transfer request messages sent by the UE; The media information integration module is configured to integrate the media information in the multiple transfer request messages received, and send the integrated media information to the peer UE. 19. The AS according to claim 18, wherein the media information integration module is configured to integrate the media information in multiple transfer request messages according to the order of the media lines of the multimedia session, and integrate the integrated The media information is sent to the peer UE. 20. The AS according to claim 18, wherein the AS further comprises: The timer is used to record the waiting time for the transfer request message, and when the recorded waiting time exceeds the preset waiting time, notify the media information integration module not to integrate the timed-out transfer request message. 21. A user equipment UE, characterized in that the UE comprises: A transfer request message sending module, configured to send a transfer request message to the application server AS; The first access network transfer information sending module is configured to send the access network transfer information to the AS, and the access network transfer information is used to make the AS know that the multimedia session of the UE needs to transfer to the circuit-switched CS domain of the Universal Mobile Telecommunications System UMTS network and packet exchange PS field for transfer. 22. The UE according to claim 21, wherein the UE further comprises: The second access network transfer information receiving module is configured to receive the access network transfer information sent by the AS. the

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