CN101370176B

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

Info

Publication number: CN101370176B
Application number: CN2007101452612A
Authority: CN
Inventors: 龙水平; 金辉
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2007-08-17
Filing date: 2007-08-17
Publication date: 2011-12-21
Anticipated expiration: 2027-08-17
Also published as: CN101370176A; WO2009024061A1

Abstract

The invention provides a method and a device of transferring multimedia session between different access networks. The method comprises that: an application server (AS) learns that the multimedia session of user equipment (UE) will be transferred to a plurality of access networks; the AS receives a plurality of transfer request messages sent by the UE, integrates the media information in the transfer request messages, and sends the integrated media information to the opposite end UE. The method and the device provided by the invention can shorten the transfer time and reduce redundant operations when the multimedia session of the UE is transferred to a plurality of access networks.

Description

Method and device for transferring multimedia session between different access networks

Technical Field

The present invention relates to the field of mobile communications technologies, and in particular, to a method and an apparatus for transferring a multimedia session between different access networks.

Background

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

When the UE in the call state detects that the surrounding wireless environment changes or other changes occur, the UE transfers according to a predefined transfer strategy. And the UE initiates a domain transfer request to the VCC AS from the domain to be transferred, the VCC AS establishes connection with the UE in the transferred domain, transfers the session connection of the opposite terminal UE to a new connection and releases the session connection of the transferred domain.

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 for indicating that a Domain Transfer needs to be initiated, and are stored in the UE. When UE is to be switched to a CS domain network, initiating a call by taking a VDN as a called number; when UE is switched to PS domain network, using VDI AS called number to initiate call, and VCC AS judges that the call is a domain transfer request message according to the called number.

With the continuous development of networks, the services of users are not limited to voice, but also develop towards diversification of video and file transmission. A typical example of transferring by a UE that is performing a multi-session in the prior art is described below. Referring to fig. 1, fig. 1 is a flowchart illustrating an implementation of a transfer according to a conventional VCC technology.

Assume that UE-1 has three media streams, i.e., Voice (Voice), Video (Video), and Text (Text), in a World Interoperability for Microwave Access (WIMAX) network for transmission in a PS network. When a transfer to a Universal Mobile Telecommunications System (UMTS) network is required, it is assumed that a voice media stream is to be transferred to a Circuit Switched (CS) domain network of the UMTS, and two other media streams are to be transferred to a Packet Switched (PS) domain network of the UMTS. According to the conventional VCC practice, the following steps are performed.

Step 101: UE-1 initiates a call in the UMTS CS domain network with VDN as the called number, which is used to identify the call as a transfer request message. The method specifically comprises the following steps: a Setup (Setup) message is sent to the Visiting Mobile Switching Center (VMSC), which sends the message to a media gateway Control function (MGCF, MGW Control function) entity.

Step 102: the MGCF performs protocol conversion, converts the CS domain signaling into an Invite message, writes Media information (i.e., a port number and an IP address of the MGW) of a Media Gateway (MGW) and Media line information (i.e., m ═ Voice) of Voice into the Invite message, and sends the Invite message to the VCC AS.

Step 103: and the VCC AS initiates a re-Invite/Update (Update) message to the UE-2 according to the anchoring information, wherein the message carries the media information of a Media Gateway (MGW) and the media line information of Voice and informs the UE-2 to Update the media information.

Step 104: UE-2 returns 200OK confirmation message to VCC AS, wherein media information of UE-2 (namely IP address and port number of UE-2) is carried.

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

Step 106: UE-1 initiates a call in the PS domain network of UMTS with VDI as the called number, which is used to identify the call as a transfer request message. The method specifically comprises the following steps: and sending an Invite message to the VCC AS, wherein the Invite message carries media information of the UE-1 (namely, the port number and the IP address of the UE-1) and media line information of the Video and Text (namely, m is Video and m is Text).

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

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

In the above process, step 101 to step 105 are used to complete the session connection between the CS domain UE-1 and the UE-2; step 106 to step 108, which are used for completing the session connection between the PS domain UE-1 and the UE-2. For step 103 and step 107, it can be seen that both steps are functionally similar, both informing the UE-2 to update the media information, and the completion of the two separate steps constitutes operational redundancy. Moreover, due to the feature that re-Invite/Update messages themselves cannot be performed simultaneously, a second re-Invite/Update message must be initiated only after the acknowledgement message 200OK of the first re-Invite/Update message arrives, which increases the transfer time of UE-1, and may cause the second transfer request to fail. Therefore, when the multimedia session is transferred between different access networks, problems of operation redundancy, too long transfer time and the like can occur.

Disclosure of Invention

In view of the above, embodiments of the present invention provide a method for transferring a multimedia session between different access networks, which is capable of shortening a transfer time and reducing operational redundancy when the multimedia session of a UE is transferred to multiple access networks.

The embodiment of the invention also provides an AS, which can shorten the transfer time and reduce the operation redundancy when the multimedia session of the UE is transferred to a plurality of access networks.

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

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

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

the AS learns that the multimedia session of the UE needs to be transferred to a Circuit Switching (CS) domain and a message switching (PS) domain of a Universal Mobile Telecommunications System (UMTS) network, receives a plurality of transfer request messages sent by the UE, integrates media information in the transfer request messages, and sends the integrated media information to the opposite-end UE.

An AS, comprising:

the first access network transfer information receiving module is used for receiving access network transfer information sent by the UE, and the access network transfer information is used for enabling the AS to know that a multimedia session of the UE needs to be transferred to a Circuit Switching (CS) domain and a message switching (PS) domain of a Universal Mobile Telecommunications System (UMTS) network;

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

and the media information integration module is used for integrating the media information in the received transfer request messages and sending the integrated media information to the opposite terminal UE.

An AS, comprising:

the access network transfer information acquisition module is used for acquiring the access network transfer information of the UE;

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

the access network transfer information is used for enabling the AS to know that the multimedia session of the UE needs to be transferred to a Circuit Switching (CS) domain and a message switching (PS) domain of a Universal Mobile Telecommunications System (UMTS) network;

A UE, comprising: a transfer request message sending module, configured to send a transfer request message to the AS; the first access network transfer information sending module is used for sending access network transfer information to the AS, and the access network transfer information is used for enabling the AS to know that the multimedia session of the UE needs to be transferred to a Circuit Switching (CS) domain and a message switching (PS) domain of a Universal Mobile Telecommunications System (UMTS) network.

It can be seen that, the method, the AS, and the UE provided in the embodiments of the present invention integrate the media information in the transfer request message, and carry the integrated media information in an update message to send to the peer UE; and the updating message is not required to be sent to the opposite terminal UE every time the transfer request message is received, so that the problems of operation redundancy and overlong transfer time existing when the multimedia session of the UE is transferred to a plurality of access networks simultaneously in the prior art are solved.

Drawings

Fig. 1 is a flow chart of an implementation of a transfer according to the conventional VCC technology;

FIG. 2 is a flowchart of an embodiment of the present invention in which the MMSC AS learns the transfer information of the access network;

FIG. 3 is a flow chart of an embodiment of the present invention in which the MMSC AS learns the access network transfer information;

FIG. 4 is a flowchart of an embodiment of the present invention in which the MMSC AS learns the access network transfer information;

FIG. 5 is a flow chart of an embodiment of the present invention in which the MMSC AS learns the transfer information of the access network;

FIG. 6 is a flowchart illustrating an implementation of the transfer according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and specific examples.

Suppose that UE-1 is currently located in a WIMAX network and is in a session with a peer UE, UE-2, that includes three media streams, i.e., voice, video and file transfer. When UE-1 is going to enter the UMTS network, UE-1 needs to transfer the voice media stream to the CS domain of the UMTS network and the video and file media streams to the PS domain of the UMTS network. The AS performing the transfer at this time is referred to AS a Multimedia Session Continuity (MMSC) AS.

In the foregoing scenario, the method for transferring a multimedia session between different access networks according to the embodiment of the present invention includes: the MMSCAS acquires that the multimedia session of the UE-1 needs to be transferred to a plurality of access networks, and the MMSC AS receives a transfer request sent by the UE-1, integrates media information of the transfer request and sends the media information to the UE-2.

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

In the above method, the precondition for integrating the two transfer request messages is that the MMSC AS must first know that the UE-1 is transferring to two access networks. The method can be learned by the MMSC AS being informed of the access network transfer information by the UE-1 initiating the transfer, and the MMSC AS returns a confirmation or rejection response to the UE-1. The access network transfer information sent by UE-1 to the MMSC AS may include: at least one of a type of each target access network to which the UE-1 is to transfer, and a number of target access networks;

or, the MMSC AS can acquire the access network transfer information through judgment of the UE-1 position information or other third party trigger information, and after the acquisition, the MMSC AS informs the UE-1, and the UE-1 returns a confirmation or rejection response to the MMSC AS. The access network transfer information sent by the MMSC AS to UE-1 may include: type of target access network to which the UE is to be transferred.

In the two learning methods, each of the two learning methods has two different modes. The following describes ways of learning access network transfer information, respectively.

Referring to fig. 2, fig. 2 is a flow chart of an embodiment of the MSC AS learning access network forwarding information according to the present invention. In the first embodiment, the access network transfer information may be carried in an intra-session message by the UE-1 and transmitted to the MMSC AS, where the transmission may be performed in an original access network where the UE-1 is located before the transfer, or may be performed in a target access network where the UE is located after the transfer. The intra-session message includes a re-Invite message, an Update message, an Info message, or the like, which will be exemplified below as being carried in the re-Invite message.

Step 201: UE-1 defines an access network transfer information indication (DTReq ═ PS/CS) for indicating that UE-1 needs to transfer in the PS domain and the CS domain simultaneously. UE-1 carries DTReq-PS/CS in re-Invite message, and sends it to MMSC AS.

The specific carrying mode can be as follows:

carried by a From header field, namely DTReq ═ PS/CS is added in the From header field; or,

carrying through a Contact header field, namely adding DTReq to PS/CS in the Contact header field; or,

the SDP message body carries, namely, a session level a line is added in the SDP message body: a ═ DTReq: < PS/CS >

Step 202: MMSC AS sends 200OK message to UE-1, carrying the supported transfer type. If the MMSC AS accepts the UE-1 request, returning the indication information AS it is; if not, then return the supported transfer types.

Referring to fig. 3, fig. 3 is a flowchart illustrating an embodiment of the MMSC AS learning access network transfer information according to the present invention. In the second embodiment, the access network transfer information may be carried in the out-of-session message by the UE-1 and transmitted to the MMSC AS, where the transmission may be performed in the original access network where the UE-1 was located before the transfer, or may be performed in the target access network where the UE was located after the transfer. The out-of-session Message includes a Notify Message, a Message, and the like, and is carried in the Notify Message as an example below.

Step 301: UE-1 defines an access network transfer information request Event (DTReq-Event) for indicating that UE-1 needs to transfer in both the PS domain and the CS domain. UE-1 carries DTReq-Event in Notify message and sends it to MMSCAS.

Step 302: and the MMSC AS returns a transfer request confirmation Event (DTConf-Event) to the UE-1, indicates the transfer type supported by the UE-1, carries the DTConf-Event in a Notify message and sends the Notify message to the UE-1. The Notify mechanism of SIP may also be employed to define a new DTConf-Event.

Two ways shown in fig. 2 and fig. 3 are to notify the MMSC AS of the access network transfer information by the UE-1, and the following describes a way in which the MMSC AS itself learns the access network transfer information and notifies the UE-1.

Referring to fig. 4, fig. 4 is a flowchart illustrating an embodiment of acquiring access network transfer information by the MMSC AS of the present invention. In the third embodiment, after obtaining the access network transfer information, the MMSC AS may carry the access network transfer information in an intra-session message to transmit to the UE-1, where the transmission may be performed in an original access network where the UE-1 was located before the transfer, or may be performed in a target access network where the UE-1 was located after the transfer. The intra-session message includes a re-Invite message, an Update message, an Info message, or the like, which will be exemplified below as being carried in the re-Invite message.

Step 401: MMSC AS defines an access network transfer information indication (DTReq ═ PS/CS) for indicating that UE-1 needs to transfer in both the PS domain and the CS domain. And the MMSC AS carries the DTReq-PS/CS in a re-Invite message and sends the message to the UE-1.

The specific carrying mode can be as follows:

Step 402: UE-1 sends 200OK message to MMSC AS, carrying the supported transfer type. If the UE-1 accepts the MMSC AS request, returning the indication information AS it is; if not, then return the supported transfer types.

Referring to fig. 5, fig. 5 is a flowchart illustrating an embodiment of acquiring access network transfer information by the MMSC AS of the present invention. In the fourth embodiment, after obtaining the access network transfer information, the MMSC AS may carry the access network transfer information in an out-of-session message to transmit to the UE-1, where the transmission may be performed in an original access network where the UE-1 was located before the transfer, or may be performed in a target access network where the UE-1 was located after the transfer. The out-of-session Message includes a Notify Message, a Message, and the like, and is carried in the Notify Message as an example below.

Step 501: the MMSC AS defines an access network transfer information request Event (DTReq-Event) for indicating that UE-1 needs to transfer in both the PS domain and CS domain. UE-1 carries the DTReq-Event in a Notify message and sends the Notify message to UE-1.

Step 502: UE-1 returns transfer request confirm Event (DTConf-Event) to MMSC AS, indicates the transfer type supported by the Event, carries the DTConf-Event in Notify message, and sends the Notify message to MMSC AS. The Notify mechanism of SIP may also be employed to define a new DTConf-Event.

In the flows shown in fig. 4 and 5, the MMSC AS may learn the access network transfer information through the judgment of the UE-1 location information or other third party trigger information. Therefore, the two ways shown in fig. 4 and fig. 5 can implement the way that the MMSC AS initiates the transfer according to the judgment of the location information of the UE-1 or the third party trigger condition, but only the UE-1 actively initiates the transfer in the prior art.

Through the steps of fig. 2, 3, 4 or 5, the MMSC AS learns that the UE-1 needs to transfer to two access networks, and on this premise, the MMSC AS waits for receiving two transfer request messages, integrates the media information in the two messages, and sends the integrated media information to the UE-2. Referring to fig. 6, fig. 6 is a flowchart of implementation of the transfer according to the embodiment of the present invention, where the steps in the flowchart are performed on the premise that the steps in fig. 2, 3, 4, or 5 have ended.

Step 601: UE-1 initiates a call in the UMTS CS domain network with VDN as the called number, which identifies the call as a transfer request message. The method specifically comprises the following steps: a Setup message is sent to the VMSC, which sends the message to the MGCF.

Step 602: the MGCF carries out protocol conversion, converts the CS domain signaling into an Invite message, writes media information of the MGW (namely, a port number, an IP address and the like of the MGW) and media line information of Voice (namely, m is Voice) into the Invite message, and sends the Invite message to the MMSC AS.

Step 603: UE-1 initiates a call in the PS domain network of UMTS with VDI as the called number, which identifies the call as a transfer request message. The method specifically comprises the following steps: and sending the message to the MMSC AS, wherein the message carries media information of the UE-1 (i.e. the port number and the IP address of the UE-1) and media line information of Video and Text (i.e. m ═ Video ═ Text).

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

Step 604: after receiving the transfer requests of the CS domain and the PS domain, the MMSC AS integrates the media line information in the two Invite messages, and adjusts the sequence of the media lines to be the same AS the sequence of the media lines when the session is established. If it is assumed that, when the session is established, the media line information included in Invite sent by UE-1 to UE-2 is m ═ Voice; m is Video; when m is Text, the sequence of the integrated media lines is: m is Voice; m is Video; and m is Text. And according to the sequence of the integrated media lines, integrating the media information in the transfer request message, namely integrating the media information comprising the media information of the MGW and the media information of the UE-1. And carrying the integrated media information in a re-Invite/Update message, and sending the re-Invite/Update message to the UE-2.

Step 605: and the UE-2 returns a 200OK confirmation message to the MMSC AS, wherein the 200OK confirmation message carries the media information of the UE-2. MMSC AS generates two paths of 200OK confirmation messages according to the media line information in the 200OK confirmation messages. And according to the media line information, confirming to which access network the generated two paths of 200OK confirmation messages are respectively sent.

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

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

In the above process, the difference from the prior art is that: in step 602, after receiving the transfer request message, the MMSC AS does not immediately carry the media information carried in the transfer request message in a re-Invite/Update message and sends the same to the UE-2; and after waiting for receiving the second transfer request message, integrating the media information in the two messages, carrying the integrated media information in a re-Invite/Update message, and sending the re-Invite/Update message to the UE-2. The improvement has the beneficial effects that two re-Invite/Update messages with similar functions in the prior art are merged and sent, so that the signaling waste and the operation redundancy caused by sending twice are avoided.

In addition, in order to avoid that the time for the MMSC AS to wait for the transfer request message is too long, the waiting time may be preset, and when the interval time between two transfer request messages exceeds the preset waiting time, the MMSC AS will not wait for the transfer request message that has not yet arrived, and the MMSC AS will only process the transfer request message that arrives within the specified time. The waiting time may be calculated from any time between the MMSC AS knowing that the multimedia session of UE-1 is to be transferred to the MMSC AS and receiving the first transfer request message, wherein the time comprises the time when the MMSC AS knowing that the multimedia session of UE-1 is to be transferred and the time when the MMSC AS receives the first transfer request message. The specific implementation mode can be as follows:

a timer is set in the MMSC AS, and after the MMSC AS receives the Invite message in step 602, the timer starts to count time, and if the time of the timer reaches the preset waiting time, the MMSC AS still does not receive the Invite message sent by the UE-1 in step 603, the message is no longer waited, and only the Invite message received in step 602 is processed. Of course, if step 603 is performed before step 601, the timer will start counting from the time the MMSCAS received the Invite message in step 603.

In addition to the above, there are various ways of timing, such as:

when the method of notifying the access network transfer information to the MMSC AS by the UE-1 shown in fig. 2 or fig. 3 is adopted before the MMSC AS receives the transfer request, timing may be started when the notification message of the UE-1 reaches the MMSCs, or may be started after the MMSC AS responds to the notification message of the UE-1.

When the MMSC AS shown in fig. 4 or 5 notifies the access network transfer information to the UE-1 before the MMSC AS receives the transfer request, timing may be started when the MMSC AS issues the notification message, or may be started after the UE-1 returns a response.

In short, the timing mode can be flexibly selected, and the purpose is not to allow the MMSC AS to wait for the arrival of the two forwarding request messages indefinitely.

It should be noted that the above embodiment is described by taking the example that the multimedia session of the UE-1 is transferred to two access networks, and the present invention is also applicable to the case that the multimedia session of the UE-1 is transferred to a plurality of access networks. When the multimedia session of the UE-1 needs to be transferred to a plurality of access networks, the AS acquires the transfer information of the access networks, integrates the media information in all the received transfer information after a plurality of transfer request messages arrive, and sends the integrated media information to the opposite-end UE. This case also can preset the waiting time to avoid the AS waiting too long for the transfer request message. When the waiting time is over and the transfer request still does not reach the AS, the AS only processes the received transfer request message and does not process the overtime transfer request message.

An embodiment of the present invention further provides an AS, where the AS includes:

a transfer request message receiving module, configured to receive a transfer request message sent by a UE;

and the media information integration module is used for integrating the media information in the received transfer request message and sending the integrated media information to the opposite terminal UE.

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 a media line sequence of the multimedia session, and send the integrated media information to the peer UE.

The AS may further include:

and the first access network transfer information receiving module is used for receiving the access network transfer information sent by the UE.

Or further comprising:

and the second access network transfer information sending module is used for sending the access network transfer information to the UE.

The AS may further include:

and the timer is used for recording the time of waiting for the transfer request message, and informing the media information integration module not to integrate the overtime transfer request message when the recorded waiting time exceeds the preset waiting time.

This embodiment further provides a UE, including: a transfer request message sending module, configured to send a transfer request message to the AS; the first access network transfer information sending module is used for sending access network transfer information to the AS, and the access network transfer information is used for enabling the AS to know that the multimedia session of the UE needs to be transferred to a plurality of access networks. (ii) a

The UE may further include: and the second access network transfer information receiving module is used for receiving the access network transfer information sent by the AS.

To sum up, according to the method for transferring a multimedia session between different access networks, the AS and the UE provided in the embodiments of the present invention, after knowing that a multimedia session of the UE needs to be transferred to multiple access networks, the AS waits to receive multiple transfer request messages, integrates media information in the transfer request messages, and carries the integrated media information in an update message to send to the UE at the opposite end. By the method, the problems of operation redundancy, overlong transfer time and the like existing when the multimedia session of the UE is transferred to a plurality of access networks simultaneously in the prior art are solved. In addition, the embodiment of the invention also supports AS to actively initiate transfer, and the AS can inform the UE to transfer through the judgment of the UE position information or other third party trigger information. In addition, in order to avoid the overlong time for the AS to wait for receiving the transfer request message, the invention can set the waiting time, and when the time is exceeded, the AS will not process the transfer request message which arrives overtime.

In summary, the above is merely illustrative of the spirit of the present invention and is not meant to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

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

the application server AS learns that the multimedia session of the user equipment UE needs to be transferred to a Circuit Switching (CS) domain and a message switching (PS) domain of a Universal Mobile Telecommunications System (UMTS) network, receives a plurality of transfer request messages sent by the UE, integrates media information in the transfer request messages, and sends the integrated media information to the opposite terminal UE.

2. The method according to claim 1, wherein the integrating the media information in the plurality of transfer request messages specifically comprises:

and integrating the media information in the plurality of transfer request messages according to the media line sequence of the multimedia session.

3. The method of claim 1, wherein the learning step comprises:

UE sends access network transfer information to AS, and AS acquires the information according to the received access network transfer information;

the access network transfer information includes: at least one of a type of each target domain to which the UE is to transfer, and a number of target domains.

4. The method of claim 1, wherein the learning step comprises: the AS judges the UE position information and acquires the UE position information according to a judgment result; or the AS learns from third party trigger information.

5. The method of claim 4, wherein after the learning and before the receiving, further comprising: the AS sends access network transfer information to the UE, wherein the access network transfer information comprises the type of a target domain to be transferred by the UE.

6. The method according to claim 3 or 5, wherein the sending the access network transfer information is performed in an original access network where the UE is located before the transfer or in a target domain where the UE is located after the transfer.

7. The method of claim 3 or 5, wherein the access network transfer information is carried in an intra-session message.

8. The method of claim 7, wherein the intra-session messaging comprises: re-Invite message, Update message, or notify Info message.

9. The method of claim 7, the manner in which the access network transfer information is carried in an intra-session message comprises:

the access network transfer information is carried in the header parameters of the intra-session message or in the session description protocol SDP body of the intra-session message.

10. The method of claim 3 or 5, wherein the access network transfer information is carried in an out-of-session message.

11. The method of claim 10, wherein the out-of-session message comprises: notify Message or Message.

12. The method of claim 1, further comprising: presetting waiting time of a transfer request message;

the AS receiving the transfer request message sent by the UE comprises: and receiving a transfer request message within the preset waiting time.

13. The method of claim 12, wherein the waiting time is calculated from any time the AS knows that the multimedia session of the UE is to be transferred to any time the AS receives the first transfer request message.

14. The method of claim 1, wherein after the AS sends the integrated media information to the peer UE, the method further comprises:

and the opposite terminal UE returns a confirmation message to the AS, the AS generates a multi-path confirmation message according to the media line information contained in the confirmation message, and sends the generated multi-path confirmation message to the UE in a Circuit Switching (CS) domain and a message switching (PS) domain of the Universal Mobile Telecommunications System (UMTS) network respectively.

15. An application server, AS, comprising:

a first access network transfer information receiving module, configured to receive access network transfer information sent by a user equipment UE, where the access network transfer information is used to enable an AS to know that a multimedia session of the UE needs to be transferred to a circuit switched CS domain and a packet switched PS domain of a UMTS network;

16. The AS claimed in claim 15, wherein the media information integration module is configured to integrate the media information in the multiple transfer request messages according to a media line sequence of the multimedia session, and send the integrated media information to the peer UE.

17. The AS of claim 15, wherein the AS further comprises:

18. An application server, AS, comprising:

the access network transfer information acquisition module is used for acquiring access network transfer information of User Equipment (UE);

19. The AS claimed in claim 18, wherein the media information integration module is configured to integrate the media information in the multiple transfer request messages according to a media line sequence of the multimedia session, and send the integrated media information to the peer UE.

20. The AS of claim 18, wherein the AS further comprises:

21. A user equipment, UE, comprising:

a transfer request message sending module, configured to send a transfer request message to an application server AS;

the first access network transfer information sending module is used for sending access network transfer information to the AS, and the access network transfer information is used for enabling the AS to know that the multimedia session of the UE needs to be transferred to a Circuit Switching (CS) domain and a message switching (PS) domain of a Universal Mobile Telecommunications System (UMTS) network.

22. The UE of claim 21, wherein the UE further comprises:

and the second access network transfer information receiving module is used for receiving the access network transfer information sent by the AS.