CN101325733A - Method for implementing call retention and call recuperation of centralized service of IP multimedia subsystem - Google Patents

Abstract

This invention discloses a realizing method of call hold and call recover of IMS centralized business, which is used for realizing the call hold and call recover between the local IMS centralized business UE and remote UE, including following steps: the local IMS centralized business UE sends the request information or call hold or call recover to an IP multimedia sub-system circuit domain control function; the request information takes the media working mode instruction set by the local IMS centralized business UE; the IP multimedia sub-system circuit domain control function respectively sends the corresponding media working mode to the remote UE and a media gateway control function; the remote UE sets the media working mode of its own end based on received media working mode instruction; the media gateway control function sets the media working mode of the media gateway based on the received media working mode instruction. Adopting the method of this invention, the call hold and call recover of IMS centralized business can be realized.

Description

The IP Multimedia System centralized traffic is called out and is kept and the call recovery implementation method

Technical field

The present invention relates to IP (network interconnection agreement, Internet Protocol are called for short IP) IP multimedia subsystem, IMS (IP Multimedia Core Network Subsystem is called for short IMS), relate in particular to the IMS centralized traffic and call out maintenance and call recovery implementation method.

Background technology

IMS is a kind of IP-based network framework that is proposed by third generation partner program (3rd Generation Partnership Project is called for short 3GPP).It has made up an opening and service environment flexibly, supports multimedia application, and provides abundant multimedia service for the user.

IMS is based on the communication network framework of IP, irrelevant with access technology, except being GPRS (General Packet Radio Service, GPRS), WLAN (Wireless LocalArea Network, WLAN (wireless local area network)) etc. packet access network provides outside the business, can also be GSM (Global System for Mobile communications, global system for mobile communications), UMTS mobile cellular networks such as (Universal Mobile Telecommunications System, unified mobile communcations systems) provides professional.

Mobile cellular network such as GSM, UMTS adopts circuit-switched technology, is called circuit (CircuitSwitched is called for short CS) territory, can provide basic speech business for the user, and based on the supplementary service of speech business.When IMS was inserted in the CS territory, it developed into a kind of access way, and business provides by IMS is unified fully, and this technology is called IMS centralized traffic (IMS Centralized Service is called for short ICS).

Fig. 1 is the Organization Chart of IMS centralized traffic scene, and following network element is arranged:

101 subscriber equipmenies (User Equipment is called for short UE)

102 Visited Mobile Switching Centers (Visited Mobile Switch Center is called for short VMSC)

103 home subscriber servers (Home Subscriber Server is called for short HSS)

104 MGCFs (Media Gateway Control Function is called for short MGCF)

105 media gateway (Media Gateway is called for short MGW)

106IMS circuit domain control function (IMS CS Control Function is called for short ICCF)

107 CSCFs (Call Session Control Function is called for short CSCF)

UE_101 builds together to the IMS territory and founds 3 paths, is respectively: session control path, carrying control path and bearer path.

Wherein session information is transmitted in the session control path between UE_101 and ICCF_106 following dual mode:

(1) CS session control path: be carried on the CS territory, adopt unstructured supplementary service data (Unstructured Supplementary Service Data is called for short USSD), this path is through VMSC_102 and HSS_103.

(2) CS session control path: be carried on the PS territory, adopt session initiation protocol (Session InitialProtocol is called for short SIP), this path is through the CSCF_107 in IP bearer network, the IMS territory.

The foundation of bearer path and the management of bearing resource are being controlled in carrying control path, and UE_101 adopts the CS control signaling of standard to insert VMSC_102, and is linked into IMS by MGCF_104, arrives ICCF through CSCF_107.

Bearer path is that UE_101 is linked into IMS by VMSC_102 and MGW_105, and sets up medium with the remote user equipment of this session and be connected.

The IMS centralized traffic is utilized the interactive sessions control information between UE_101 and ICCF_106 of session control path, and sets up and the control media bearer by carrying control path, and ICCF_106 serves as IMS subscriber equipment agency, replaces subscriber equipment to insert IMS.

Calling maintenance (Call Hold) business is a kind of supplementary service in the communication system, comprises calling out keeping and two processes of call recovery.When two users (user A and user B) set up conversation in communication system after, one of them user (is example with user A) can ask remote subscriber (user B) to keep current talking to connect, but does not carry out voice transfer, and this is for calling out the maintenance process.The UE (UE-B) of the UE of user A (UE-A) and user B can also change talking state over to again from calling out hold mode, and this process is called call recovery (Call Resume) process.

Calling out in the maintenance, user A can dial or answer third party such as user C, the conversation between foundation and the user C.User A can also and two conversations of user B and user C between switch.

ICS must support call keep professional as a kind of telecommunication system.In present ICS, calling out maintenance and call recovery is by ICS notification of user equipment ICCF, replaces the ICS subscriber equipment to carry out calling by ICCF and keeps and the call recovery process, remain routine explanation implementation with calling below, and detailed process as shown in Figure 2.

UE-A possesses the ICS ability, by equipment such as VMSC, ICCF, MGCF, CSCF set up and distance terminal UE-B between conversation, and set up two-way medium by VMSC, MGW and UE-B and be connected.When user A wishes to start the calling maintenance,, following steps are arranged referring to Fig. 2:

Step 201, UE-A sends to call out to ICCF by the session control path and keeps request.

Step 202, ICCF sends medium updating message (respectively shown in Reference numeral 202a and 202b) to UE-B and MGCF respectively, the medium working method is " un-activation " in the request message, indicates UE-B and MGCF to enter unactivated state respectively, does not receive and does not also send Media Stream.

Step 203, the media resource that UE-B controls this terminal is moved to " un-activation " state, does not receive and does not also send Media Stream, and return medium to ICCF and upgrade success response (shown in Reference numeral 203a); The media resource that MGCF also controls MGW is moved to " un-activation " state, does not receive and does not also send Media Stream, and return medium to ICCF and upgrade success response (shown in Reference numeral 203b).

Step 204 after ICCF receives the success response of UE-B and MGCF, is returned calling by the session control path to UE-A and is kept success response.

At this moment, UE-A and UE-B enter the calling hold mode, and the Media Stream between MGW and the UE-B interrupts, and also be still to keep conversation to connect between UE-A and the UE-B, but Media Stream interrupt.

When UE-A wish to recover and UE-B between media delivery the time, the maintenance process is similar with calling out.Send the call recovery request to ICCF by UE-A, ICCF sends the medium updating message to UE-B and MGCF respectively, indication UE-B and MGCF/MGW arrive media resource state transition " send and receive " state respectively, send simultaneously and reception work, thereby recover original talking state.

There is following problem in present this implementation:

(1) according to calling out the requirement that keeps, when two parties all is in talking state, keeps request, comprise " only sending " indication in the request message when a user (for example user A) sends to call out to another one user (user B).After calling kept successfully, UE-A was in " only sending " state (Sendonly), sends Media Stream to UE-B, and no longer receives the Media Stream of UE-B; UE-B is in " receiving only " state (Recvonly), receives only the opposite end Media Stream, and no longer sends Media Stream to the opposite end, promptly only has the one-way media stream of UE-A to UE-B, can be play to UE-B by UE-A or network this moment to keep the sound prompting.

If UE-A is in " receiving only " state, UE-B is in " only sending " state, and UE-A sends to call out to UE-B and keeps, and comprises " un-activation " indication in the request message.After calling kept successfully, UE-A and UE-B were in " un-activation " state, stopped to send and receiving media stream.

Therefore present method is to directly migrate to " un-activation " state from " send and receive " state, can't satisfy the demand that remains under the different conditions of calling out.

(2) calling out under the hold mode; usually can play the maintenance sound to maintained UE by network, if send the medium indication that contains " non-activation " to maintained UE, maintained UE will stop to receive and sending; network can't be play to maintained UE and keep sound this moment, thereby influenced user experience.

In sum, present ICS calls out the maintenance method can't satisfy the business demand of calling out maintenance, and influence is held user's business experience.

Summary of the invention

Technical problem to be solved by this invention is to be to provide a kind of IMS centralized traffic to call out to keep and the call recovery implementation method, to satisfy the business demand of call hold service in the IMS centralized traffic.

In order to solve the problems of the technologies described above, the present invention at first provides a kind of IP Multimedia System centralized traffic to call out the maintenance implementation method, in order to realize that the calling between local IP Multimedia System centralized traffic subscriber equipment and the remote user equipment keeps, and comprises the steps:

(1) described local IP Multimedia System centralized traffic subscriber equipment sends to call out to the IP Multimedia System circuit domain control function and keeps request message, described calling to keep carrying in the request message the set medium working method indication of described local IP Multimedia System centralized traffic subscriber equipment;

(2) described IP Multimedia System circuit domain control function sends to described remote user equipment and MGCF respectively with corresponding medium working method indication;

(3) described remote user equipment is provided with the medium working method of local terminal according to the medium working method indication that receives; Described MGCF is provided with the medium working method of media gateway according to the medium working method indication that receives, and the calling of finishing between described local IP Multimedia System centralized traffic subscriber equipment and the remote user equipment keeps.

Call out according to above-mentioned IP Multimedia System centralized traffic and to keep implementation method, the indication of medium working method described in the step (1) can be provided with according to current self medium operating state by described local IP Multimedia System centralized traffic subscriber equipment.

Further, current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment can comprise " send and receive " state or " receiving only " state.

Again further, in the step (1): if current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment is described " send and receive " state, it can be " only sending " state that then described medium working method is provided with; If current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment is described " receiving only " state, then described medium working method is provided with and can be " un-activation " state.

Further, if the medium working method is designated as described in the described step (1) " only send " state, then IP Multimedia System circuit domain control function described in the step (2) can be designated as " only sending " state to the medium working method that described remote user equipment sends, and can be designated as " receiving only " state to the medium working method that described MGCF sends; If the medium working method is designated as " un-activation " state described in the described step (1), then IP Multimedia System circuit domain control function described in the step (2) can be designated as " un-activation " state to the medium working method of described remote user equipment and the transmission of described MGCF.

Call out the maintenance implementation method according to above-mentioned IP Multimedia System centralized traffic, IP Multimedia System circuit domain control function described in the step (2) can be upgraded or heavily invitation request by medium, and corresponding medium working method is sent to described remote user equipment and MGCF respectively.

Further, described IP Multimedia System circuit domain control function adopts the request of heavily inviting to send described medium working method, then the described afterwards IP Multimedia System circuit domain control function of step (3) can further send acknowledge message to described remote user equipment or described MGCF after receiving the heavily invitation success response that described remote user equipment or described MGCF return.

Call out the maintenance implementation method according to above-mentioned IP Multimedia System centralized traffic, may further include:

(4) described remote user equipment and described MGCF return medium renewal success response to described IP Multimedia System circuit domain control function;

(5) described IP Multimedia System circuit domain control function is returned to call out to local IP Multimedia System centralized traffic subscriber equipment and is kept success response.

The present invention and then a kind of IP Multimedia System centralized traffic call recovery implementation method is provided in order to realize the call recovery between local IP Multimedia System centralized traffic subscriber equipment and the remote user equipment, comprises the steps:

(a) described local IP Multimedia System centralized traffic subscriber equipment sends the call recovery request message to the IP Multimedia System circuit domain control function, carries the set medium working method indication of described local IP Multimedia System centralized traffic subscriber equipment in the described call recovery request message;

(b) described IP Multimedia System circuit domain control function sends to described remote user equipment and MGCF respectively with corresponding medium working method indication;

(c) described remote user equipment is provided with the medium working method of local terminal according to the medium working method indication that receives; Described MGCF is provided with the medium working method of media gateway according to the medium working method indication that receives, and finishes the call recovery between described local IP Multimedia System centralized traffic subscriber equipment and the remote user equipment.

According to above-mentioned IP Multimedia System centralized traffic call recovery implementation method, medium working method described in the step (a) indication can be provided with according to current self medium operating state by described local IP Multimedia System centralized traffic subscriber equipment.

Further, current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment can comprise " un-activation " state or " only sending " state.

Again further, in the step (a): if current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment is described " un-activation " state, then described medium working method can be set to " receiving only " state; If current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment is described " only sending " state, then described medium working method can be set to " send and receive " state.

Further, if the medium working method is designated as " receiving only " state described in the described step (a), then IP Multimedia System circuit domain control function described in the step (b) can be designated as " receiving only " state to the medium working method that described remote user equipment sends, and can be designated as " only sending " state to the medium working method that described MGCF sends; If the medium working method is designated as described in the described step (a) " send receive " state, then IP Multimedia System circuit domain control function described in the step (b) can be designated as " send and receive " state to the medium working method that described remote user equipment and described MGCF send.

According to above-mentioned IP Multimedia System centralized traffic call recovery implementation method, IP Multimedia System circuit domain control function described in the step (b) can be upgraded or heavily invitation request by medium, and corresponding medium working method is sent to described remote user equipment and MGCF respectively.

Further, described IP Multimedia System circuit domain control function adopts the request of heavily inviting to send described medium working method, then the described afterwards IP Multimedia System circuit domain control function of step (c) can further send acknowledge message to described remote user equipment or described MGCF after receiving the heavily invitation success response that described remote user equipment or described MGCF return.

IP Multimedia System centralized traffic call recovery implementation method according to above-mentioned may further include:

(d) described remote user equipment and described MGCF return medium renewal success response to described IP Multimedia System circuit domain control function;

(e) described IP Multimedia System circuit domain control function is returned the call recovery success response to local IP Multimedia System centralized traffic subscriber equipment.

Adopt the method for the invention, the ICS subscriber equipment sends to call out to ICCF according to current medium operating state and keeps or the call recovery request, ICCF carries out corresponding medium control according to notice far-end UE of the medium working method in the request and MGCF/MGW again, keeps or call recovery thereby realized calling out in the IMS centralized traffic.

Description of drawings

Fig. 1 is the configuration diagram of IMS centralized traffic embodiment in the prior art;

Fig. 2 is that ICS calls out maintenance embodiment schematic flow sheet in the prior art;

Fig. 3 keeps the embodiment schematic flow sheet for ICS of the present invention calls out;

Fig. 4 is an ICS call recovery embodiment schematic flow sheet of the present invention;

Fig. 5 keeps service implementation example schematic flow sheet for ICS full call of the present invention.

Embodiment

The present invention is described in further detail below in conjunction with the drawings and specific embodiments.

Fig. 3 shows and calls out the flow process that keeps among the present invention, comprises the steps:

Step 301, the local IMS centralized traffic of ICS UE sends to call out to ICCF by the session control path and keeps request message, carries local IMS centralized traffic UE in the request message according to current self the set medium working method indication of medium operating state;

Step 302, ICCF sends to far-end UE and MGCF (shown in step 302a and step 302b) respectively with corresponding medium working method indication;

Step 303, far-end UE is provided with the medium working method (shown in step 303a) of local terminal according to the medium working method indication that receives; MGCF is provided with the medium working method (shown in step 303b) of MGW according to the medium working method indication that receives;

Step 304, far-end UE and MGCF all return medium to ICCF and upgrade success response (shown in step 304a and step 304b);

Step 305, ICCF returns calling by the session control path to local IMS centralized traffic UE and keeps success response after receiving that the medium of far-end UE and MGCF transmission upgrade success response, and at this moment, local IMS centralized traffic UE and far-end UE enter the calling hold mode.

In the step 301, current self the medium operating state of local IMS centralized traffic UE comprises " send and receive " state or " receiving only " state.Further, if current self the medium operating state of local IMS centralized traffic UE is " send and receive " state, then the medium working method is set to " only sending "; If current self the medium operating state of local IMS centralized traffic UE is " receiving only " state, then the medium working method is set to " un-activation ".

In the step 302, ICCF upgrades by medium or heavily invites request, and corresponding medium working method is sent to remote user equipment and MGCF respectively.Further, if ICCF adopts the request of heavily inviting to send the medium working method, after then ICCF received medium renewal success response in step 304, needing also was that far-end UE or MGCF send acknowledge message to the opposite end respectively.

If local IMS centralized traffic UE keeps the medium working method in the request message to be designated as " only sending " to the calling that ICCF sent in the step 301, then ICCF is designated as " only sending " to the medium working method that far-end UE sends in the step 302, and the medium working method that sends to MGCF is designated as " receiving only "; If local IMS centralized traffic UE keeps the medium working method in the request to be designated as " un-activation " to the calling that ICCF sent in the step 301, then ICCF is " un-activation " to the medium working method indication of far-end UE and MGCF transmission in the step 302.

Fig. 4 shows the flow process of call recovery among the present invention, comprises the steps:

Step 401, the local IMS centralized traffic of ICS UE sends the call recovery request message by the session control path to ICCF, carries local IMS centralized traffic UE in the request message according to current self the set medium working method indication of medium operating state;

Step 402, ICCF sends to far-end UE and MGCF respectively with corresponding medium working method indication;

Step 403, far-end UE is provided with the medium working method of local terminal according to the medium working method indication that receives; MGCF is provided with the medium working method of MGW according to the medium working method indication that receives;

Step 404, far-end UE and MGCF all return medium to ICCF and upgrade success response;

Step 405, ICCF returns the call recovery success response by the session control path to UE-A after receiving the success response of far-end UE and MGCF transmission.At this moment, local IMS centralized traffic UE and far-end UE recover the two-way call state.

In the step 401, current self the medium operating state of local IMS centralized traffic UE comprises " un-activation " state or " only sending " state.Further, if current self the medium operating state of local IMS centralized traffic UE is " un-activation " state, then the medium working method is set to " receiving only "; If current self the medium operating state of local IMS centralized traffic UE is " only sending " state, then the medium working method is set to " send and receive ".

In the step 402, ICCF upgrades by medium or heavily invites request, and corresponding medium working method is sent to remote user equipment and MGCF respectively.Further, if ICCF adopts the request of heavily inviting to send the medium working method, after then ICCF receives medium renewal success response in step 404, need to send acknowledge message to the opposite end respectively.

If the medium working method of local IMS centralized traffic UE in the call recovery request that ICCF sent is designated as " receiving only " in the step 401, then ICCF is designated as " receiving only " to the medium working method that far-end UE sends in the step 402, and the medium working method that sends to MGCF is designated as " only sending "; If the medium working method of local IMS centralized traffic UE in the call recovery request that ICCF sent is designated as in the step 401 " send and receive ", then ICCF is " send and receive " in the step 402 to the medium working method indication of far-end UE and MGCF transmission.

Fig. 5 also promptly shows two UE and calls out hold mode to the overall process of recovering both sides' talking state from entering for the schematic flow sheet that UE-A of the present invention and UE-B realize full call maintenance service implementation example.UE-A wherein is local IMS centralized traffic UE, possesses the ICS ability, by equipment such as VMSC, ICCF, MGCF, CSCF set up and distance terminal UE-B between conversation, and set up two-way medium by VMSC, MGW and UE-B and be connected, be in the two-way call state.This moment, the media resource of MGCF/MGW and UE-B all was in " send and receive " state.Full call keeps the flow process of service implementation example may further comprise the steps:

Step 501, when maintenance was called out in user A startup, UE-A sent calling by the session control path to ICCF and keeps asking, and the medium working method indication of carrying in this request is set to " only transmission ".

Step 502, ICCF sends the medium updating message to UE-B, the medium working method is " only sending " in this request message, and the media state of notice UE-B opposite end will be moved to " only sending " state, and require UE-B correspondingly to enter " receiving only " state (shown in step 502a); Simultaneously, ICCF also sends the medium updating message to MGCF, the medium working method is " receiving only " in this request message, UE-B prepares " receiving only " state that media state is moved to the MGCF notice, and require MGCF/MGW to enter " only sending " state at the media resource of IMS side, promptly receive the transmission Media Stream of UE-A, and UE-B is issued in the conversion back, but do not receive the Media Stream of UE-B, do not send Media Stream (shown in step 502b) to UE-A.

Step 503, the media resource of UE-B control local terminal is moved to " receiving only " state, receives only but does not send Media Stream, and return medium to ICCF and upgrade success response (shown in step 503a); And the media resource of MGCF control MGW is moved to " only sending " state, only sends Media Stream to UE-B, but does not receive the Media Stream of UE-B, also returns medium to ICCF and upgrades success response (shown in step 503b).

Step 504, ICCF returns calling by the session control path to UE-A and keeps success response after receiving the success response of UE-B and MGCF transmission.

At this moment, UE-A and UE-B enter the calling hold mode, still keep conversation to connect between UE-A and the UE-B.Only there is the one-way media stream from MGW to UE-B between MGW and the UE-B, still keeps two-way Media Stream between UE-A and the MGW.UE-A can call out third party user by the session control path, and do not need to rebulid with MGW between calling be connected.

When UE-A wish to recover and UE-B between media delivery, the maintenance process is similar with calling out, UE-A sends the call recovery request to ICCF, ICCF sends the medium updating message to UE-B and MGCF respectively, indication UE-B and MGCF/MGW arrive media resource state transition " send and receive " state respectively, send simultaneously and reception work, thereby recover original talking state.Be specially:

Step 505, UE-A sends the call recovery request by the session control path to ICCF, and the medium working method of carrying in request indication is set to " send and receive ".

Step 506, ICCF sends the medium updating message to UE-B, the medium working method is " send and receive " in the request message, and the media state of notice UE-B opposite end will be moved to " send and receive " state, and requires UE-B correspondingly to enter " send and receive " state (shown in step 506a); Simultaneously, ICCF sends the medium updating message to MGCF, the medium working method also is " send and receive " in the request message, prepare media state is moved to " send and receive " state to MGCF notice UE-B, and require MGCF/MGW to enter " send and receive " state at the media resource of IMS side, receive and send Media Stream (shown in step 506b).

Step 507, the media resource of UE-B control local terminal are moved to " send and receive " state, receive simultaneously and send Media Stream, and return medium to ICCF and upgrade success response; And the media resource of MGCF control MGW is also moved to " send and receive " state, receives simultaneously and sends Media Stream, also returns medium to ICCF and upgrades success response.

Step 508, ICCF returns the call recovery success response by the session control path to UE-A after receiving the success response of UE-B and MGCF transmission.At this moment, UE-A and UE-B recover the two-way call state.

In above-mentioned steps 502, also can adopt the request of heavily inviting.If adopt the request of heavily inviting, after ICCF receives success response in step 503, need to send to the opposite end respectively to confirm request.

Set up and call out in the process that keeps, if UE-A is in " receiving only " state, promptly only exist the one-way media from UE-B to MGW to flow in the IMS side, if need starting to call out, user A keeps, process is similar to step 501～step 504, just the medium work in the step 501 is designated as " un-activation ", the medium working method of ICCF in the medium update request of UE-B and MGCF transmission all is " un-activation " in step 502, media resource state transition does not promptly send not receiving media stream to " un-activation " yet in step 503.

Set up in the process of call recovery, if only exist UE-A to be in " un-activation " state, user A starts call recovery, and its process is similar to step 505～step 508, and just the medium work in the step 505 is designated as " receiving only "; The medium working method of ICCF in the medium update request that UE-B sent all is " receiving only " in step 506, and the medium working method in the medium update request that MGCF sends is " only sending "; The media resource state transition of UE-B is to " only send " state in step 507, and MGW in the media resource state transition of IMS side to " receiving only ", promptly recover UE-B and flow to the one-way media of MGW direction.

Adopt the method for the invention, by ICS UE according to current medium operating state, send maintenance or the call recovery request of calling out to ICCF, and in request, indicate corresponding medium working method, ICCF carries out corresponding medium control according to notice far-end UE of the medium working method in the request and MGCF/MGW again, set up corresponding medium and connect, thereby reached the business demand that satisfies call hold service in the IMS centralized traffic.

Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong within the protection range of the appended claim of the present invention.

Claims (16)

1, a kind of IP Multimedia System centralized traffic is called out and is kept implementation method, keeps in order to realize the calling between local IP Multimedia System centralized traffic subscriber equipment and the remote user equipment, it is characterized in that, comprises the steps:

(1) described local IP Multimedia System centralized traffic subscriber equipment sends to call out to the IP Multimedia System circuit domain control function and keeps request message, described calling to keep carrying in the request message the set medium working method indication of described local IP Multimedia System centralized traffic subscriber equipment;

(2) described IP Multimedia System circuit domain control function sends to described remote user equipment and MGCF respectively with corresponding medium working method indication;

(3) described remote user equipment is provided with the medium working method of local terminal according to the medium working method indication that receives; Described MGCF is provided with the medium working method of media gateway according to the medium working method indication that receives, and the calling of finishing between described local IP Multimedia System centralized traffic subscriber equipment and the remote user equipment keeps.

2, the method for claim 1 is characterized in that,

Medium working method described in the step (1) indication is provided with according to current self medium operating state by described local IP Multimedia System centralized traffic subscriber equipment.

3, method as claimed in claim 2 is characterized in that,

Current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment comprises " send and receive " state or " receiving only " state.

4, method as claimed in claim 3 is characterized in that,

In the step (1):

If current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment is described " send and receive " state, then described medium working method is set to " only sending " state;

If current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment is described " receiving only " state, then described medium working method is set to " un-activation " state.

5, method as claimed in claim 4 is characterized in that,

If the medium working method is designated as described in the described step (1) " only send " state, then IP Multimedia System circuit domain control function described in the step (2) is designated as " only sending " state to the medium working method that described remote user equipment sends, and the medium working method that sends to described MGCF is designated as " receiving only " state;

If the medium working method is designated as " un-activation " state described in the described step (1), then IP Multimedia System circuit domain control function described in the step (2) is designated as " un-activation " state to the medium working method of described remote user equipment and the transmission of described MGCF.

6, the method for claim 1 is characterized in that,

IP Multimedia System circuit domain control function described in the step (2) is upgraded by medium or is heavily invited request, and corresponding medium working method is sent to described remote user equipment and MGCF respectively.

7, method as claimed in claim 6 is characterized in that,

Described IP Multimedia System circuit domain control function adopts the request of heavily inviting to send described medium working method, then the described afterwards IP Multimedia System circuit domain control function of step (3) further sends acknowledge message to described remote user equipment or described MGCF after receiving the heavily invitation success response that described remote user equipment or described MGCF return.

8, the method for claim 1 is characterized in that, further comprises:

(4) described remote user equipment and described MGCF return medium renewal success response to described IP Multimedia System circuit domain control function;

(5) described IP Multimedia System circuit domain control function is returned to call out to local IP Multimedia System centralized traffic subscriber equipment and is kept success response.

9, a kind of IP Multimedia System centralized traffic call recovery implementation method in order to realize the call recovery between local IP Multimedia System centralized traffic subscriber equipment and the remote user equipment, is characterized in that, comprises the steps:

(a) described local IP Multimedia System centralized traffic subscriber equipment sends the call recovery request message to the IP Multimedia System circuit domain control function, carries the set medium working method indication of described local IP Multimedia System centralized traffic subscriber equipment in the described call recovery request message;

(b) described IP Multimedia System circuit domain control function sends to described remote user equipment and MGCF respectively with corresponding medium working method indication;

(c) described remote user equipment is provided with the medium working method of local terminal according to the medium working method indication that receives; Described MGCF is provided with the medium working method of media gateway according to the medium working method indication that receives, and finishes the call recovery between described local IP Multimedia System centralized traffic subscriber equipment and the remote user equipment.

10, method as claimed in claim 9 is characterized in that,

Medium working method described in the step (a) indication is provided with according to current self medium operating state by described local IP Multimedia System centralized traffic subscriber equipment.

11, method as claimed in claim 10 is characterized in that,

Current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment comprises " un-activation " state or " only sending " state.

12, method as claimed in claim 11 is characterized in that,

In the step (a):

If current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment is described " un-activation " state, then described medium working method is set to " receiving only " state;

If current self the medium operating state of described local IP Multimedia System centralized traffic subscriber equipment is described " only sending " state, then described medium working method is set to " send and receive " state.

13, method as claimed in claim 12 is characterized in that,

If the medium working method is designated as " receiving only " state described in the described step (a), then IP Multimedia System circuit domain control function described in the step (b) is designated as " receiving only " state to the medium working method that described remote user equipment sends, and the medium working method that sends to described MGCF is designated as " only sending " state;

If the medium working method is designated as described in the described step (a) " send receive " state, then IP Multimedia System circuit domain control function described in the step (b) is designated as " send and receive " state to the medium working method that described remote user equipment and described MGCF send.

14, method as claimed in claim 9 is characterized in that,

IP Multimedia System circuit domain control function described in the step (b) is upgraded by medium or is heavily invited request, and corresponding medium working method is sent to described remote user equipment and MGCF respectively.

15, method as claimed in claim 14 is characterized in that,

Described IP Multimedia System circuit domain control function adopts the request of heavily inviting to send described medium working method, then the described afterwards IP Multimedia System circuit domain control function of step (c) further sends acknowledge message to described remote user equipment or described MGCF after receiving the heavily invitation success response that described remote user equipment or described MGCF return.

16, method as claimed in claim 9 is characterized in that, further comprises:

(d) described remote user equipment and described MGCF return medium renewal success response to described IP Multimedia System circuit domain control function;

(e) described IP Multimedia System circuit domain control function is returned the call recovery success response to local IP Multimedia System centralized traffic subscriber equipment.

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