CN102244911B - The cross-domain changing method of a kind of calling based on IP Multimedia System and system - Google Patents

Abstract

The present invention provides cross-domain changing method and the system of a kind of calling based on IP Multimedia System, described method, including: in caller in the call request procedure of called initiation, callee side bifurcated (forking) produces the response of multiple dialogue；In described call request procedure, if described caller is initiated from packet switch (PS) territory to the switching in circuit switching (CS) territory, the plurality of dialogue is carried out simultaneously the renewal of media resource.

Description

The cross-domain changing method of a kind of calling based on IP Multimedia System and system

Technical field

The present invention relates to the communications field, relate more specifically to a kind of method managing media resource in the ip multimedia subsystem and module.

Background technology

In present mobile network, a large amount of based on PS (PacketSwitch, packet domain exchange network) network (E-UTRAN, UTRAN-HSPA) being deployed, but its covering is not whole network area entirely, the signal at some local PS network can be very poor, it is accomplished by this time providing the user PS to traditional C/S (CircuitSwitch, circuit domain exchange network) switching of (UTRAN, GERAN), especially when user conversates time.

Fig. 1 is a kind of switching mode approved by normal structure, first UE1 is with carrying out a session between UE2, and it is based on IMS (IPMultimediaCoreNetworkSubsystem, IP Multimedia System) PS carrying, its session is anchored on SCCAS (ServiceCentralizationandContinuityApplicationServe, grappling and associated application server).In the process that call carries out, UE1 moves to the better region of the CS network coverage, at this moment the signal testing report that UE1 will receive, and by original PS network, issue MME (MobilityManagementEntity, mobile management device), after MME receives test report, judge whether to carry out PS to CS switching, now the handover request of PS to CS is sent on the mobile switching centre (MSCserver) that can cover UE1 by MME, and by the STN-SR (SessionTransferNumberforSRVCC of this user, SRVCC Handover Number, this number is directed to SCCAS's) number is sent to this MSCserver, this MSCserver sends handover request again through sip message to IMS network, namely request address in this handover request is the address of equipment pointed by this STN-SR number；Owing to this STN-SR number is directed to SCCAS's, after SCCAS receives handover request, the ongoing current session of UE1 can be found, and initiate to deserve the renewal of front dialogue, namely it is update the session with UE2 in this instance, while MSCserver sends handover request to IMS network, also can return, to MME, the response that a switching completes, switching is completed response and returns to UE1 by MME, when UE1 begins to the drop connection with PS network after receiving and having switched response, and set up connection by MSCSERVER with CS network.After the switching of IMS side and the switching of EPC side all complete, namely whole switching completes.

For an ongoing calling, namely caller sends call request, and the called ringing condition that is in is but without response, and at this moment caller can hear called ring back tone.For such calling, can also switch over when meeting switching condition.Fig. 2 (a) and Fig. 2 (b) is the switching flow schematic diagram in prior art for an ongoing calling, specifically includes:

201, calling subscribe UEA initiation one rises to call for be asked；

After 202, IMS network elements receive this call request, owing to UEA is a SCUE, this request call can be anchored into SCCAS；

203, SCCAS after Session Anchor, will be then forwarded to IMS network element S-CSCF；

This call request is sent to called subscriber UEB by called network by 204, IMS network elements；

205～208, after UEB receives this call request, reply 180 ring responses to caller, this response reaches calling subscribe UEA by IMS network element；

Now UEA can hear the other side's ring, is in the state waiting the other side's response.

If now UEA there occurs that movement, current network conditions there occurs change, trigger PS-CS switching flow.

209, when MSCserver receives the MME handover request sent, use the STN-SR number wherein received, send handover request to IMS network element, the MSCserver media resource information that can provide wherein is provided；

210, this handover request is sent to SCCAS by IMS network element；

210a, SCCAS find this calling subscribe UEA dialogue currently activated recently to be updated, and are namely the dialogue between UEA and UEB in this example；

211～212, SCCAS sends the more newly requested of current session to UEB；

213～214, UEB receive this more newly requested after, namely to SCCAS reply update response；

215～216, after SCCAS receives the renewal response of far-end, send 18X according to this renewal response to MSCserver and switch response；

217～218, MSCserver reserves the resource in PS territory, and replys an interim request after receiving 18X switching response for this dialogue；

219～220, SCCAS returns an interim request-reply to MSCserver；

221～222, SCCAS sends an INFO to MSCserver again, tells MSCserver, and the session of current switching is in ringing condition, it is necessary to MSCserver carries out corresponding CS state；

223～224, after MSCserver receives INFO, return a response；

225, MSCSERVER enters in corresponding CS session status simultaneously, is now that session sends state

226, this calling of now called UE B response, reply 200OK response (also referred to as off-hook response, or referred to as response) to caller；

227～229, owing to this session being switched on MSCserver before, so this 200OK response can be sent on MSCserver；

230, MSCserver receive this 200OK response after, namely conversate on-state, is connected by CS simultaneously and sends CS connection message to calling UE A, it was shown that called has answered that；

231, now calling UE A has had been switched to CS network, after receiving CS connection message, returns the response of CS connection message to MSCserver；

232～235, after MSCserver receives the response of CS connection message, namely send ACK message to called UE B；

236～237, now S-CSCF can send, to PS network original for UEA, the dialogue set up before 404 responses terminate at PS network；

238～239, if now UEA also having PS to connect, then reply ACK to S-CSCF；

Namely now this ongoing calling switches and completes.

In the above example, do not account for the called scene that forking occurs, namely called have multiple UE to share same PUI (PublicUseridentity common user's sign), now the call request of caller can be sent respectively to each UE by IMS network element, calling subscribe can set up multiple dialogue in this scenario, shown in such as Fig. 3 (a) of switching flow now and Fig. 3 (b), in this example, SCCAS or MSCserver or UEA wherein has one not support the mid-call i.e. scene of many dialogue switchings:

301, calling subscribe UEA initiation one rises to call for be asked；

302, after caller IMS network element receives this call request, owing to UEA is a SCUE, this request call can be anchored into SCCAS；

303, SCCAS after Session Anchor, will be then forwarded to caller IMS network element S-CSCF；

304, this call request is sent to called IMS network element by caller IMS network element；

305～306, called IMS NE Discovery is called exists multiple UE, then forking occurs, and sends call request to each UE (UE#2, UE#3) respectively；

307～311, UE#2 replys 18X response by called IMS network element and caller IMS network element to calling subscribe UEA, now sets up dialogue 1；

312～316, UE#3 replys 18X response by called IMS network element and caller IMS network element to calling subscribe UEA, now sets up dialogue 2；

Now UEA can hear the other side's ring, is in the state waiting the other side's response.

If now UEA there occurs that movement, current network conditions there occurs change, trigger PS-CS switching flow,

317, when MSCserver receives the MME handover request sent, use the STN-SR number wherein received, send handover request to IMS network element, the MSCserver media resource information that can provide wherein is provided；

318, this handover request is sent to SCCAS by IMS network element；

318a, SCCAS finds this calling subscribe UEA dialogue currently activated recently to be updated, if talking with 1 in this example is activate recently, then more newly requested for dialogue 1 initiation, owing to SCCAS or MSCserver or UEA wherein has one not support, namely mid-call talks with switching more, can not use the flow process of mid-call, then other dialogues set up on calling subscribe UEA can all be discharged by SCCAS, including dialogue 2；

319～331, with 211～225 in Fig. 2, the far-end namely completing dialogue 1 updates, and informs that MSCserver enters in corresponding CS state；

Due to called create forking, UE#2 and UE#3 all can ring,

332a～342a, if UE#2 first replys this calling, due to UE#2 with the UEA dialogue 1 successful switch set up to CS network, then according to 226～235 in Fig. 2, completes the response of calling, has switched, the switching of calling is not affected；

332b～335b, if UE#3 first replys this calling, after the UE#3 200OK sent arrives SCCAS, owing to UE#3 is released in the process of switching with the dialogue 2 set up between UEA, this response can not reach calling UE A, can cause the failure of this calling；

Owing to caller network is difficult to judge called meeting by which UE is first replied, also cannot the dialogue of the last response of selecting properly switching in the process of switching, the consequence so caused is, when, after switching generation, the probability having 50% makes off-hook answer failed.

If SCCAS, MSCserver and UEA support mid-call and talky switching simultaneously, then occur switching during forking can be undertaken by Fig. 4 (a), Fig. 4 (b) and Fig. 4 (c) when called:

401～416, calling UE A sends one request of calling, due to called forking, produces 2 dialogues, dialogue 1 and dialogue 2, and its flow process is identical with in Fig. 3 301～316；

417～432, UEA side switches, and triggers handover request, assumes dialogue 1 during the dialogue activated recently in secondary example, and the renewal switching of dialogue 1 is first initiated in side, and its flow process is identical with 317～331 in Fig. 3；

433～434, due to SCCAS in this example, MSCserver and UE supports that namely mid-call talks with switching more, SCCAS sends REFER message to MSCserver, wherein carry the information of dialogue 2, in specifying due to current agreement, the dialogue of an activated state and the session of a maintenance state can only be switched, so SCCAS needs the status modifier by dialogue 2 to be maintenance state here；

435～436, after MSCserver receives REFER message, send 202 acceptance to SCCAS corresponding；

437～438, MSCserver sends a new handover request to SCCAS simultaneously, wherein carries the information of dialogue 2, it is desirable to switching dialogue 2, wherein the state of dialogue 2 is also configured as maintenance state；

439～442, after SCCAS receives this handover request, to remote subscriber initiate for dialogue 2 more newly requested；

443～445, far-end UE#3 receive more newly requested after, reply far-end update response；

446～447, SCCAS adopts the renewal response received to reply switching response message to MSCserver；

The now switching of dialogue 2 also completes, but dialogue 2 states now are to maintain state.

448a～460a, if UE#2 first replys, owing to dialogue 1 has switched, now calling can normally be set up；

448b～460b, if UE#3 first replys, although dialogue 2 has switched, but dialogue 2 has been configured to maintenance state in the process of switching, even if now UE#3 have answered this calling, due to obstructed, both sides also cannot be carried out call.So also there will be the phenomenon of call failure under this scene.

Summary of the invention

The present invention provides a kind of method managing media resource in the ip multimedia subsystem and module, it is ensured that in call establishment, caller does not have call failure after being switched to CS territory from PS territory.

For solving above-mentioned technical problem, the technical scheme is that

A kind of cross-domain changing method of the calling based on IP Multimedia System, including:

In caller in the call request procedure of called initiation, callee side bifurcated (forking) produces the response of multiple dialogue；

In described call request procedure, if described caller is initiated from packet switch (PS) territory to the switching in circuit switching (CS) territory, the plurality of dialogue is carried out simultaneously the renewal of media resource.

Preferably, described method also has a characteristic that the described response producing multiple dialogues due to callee side bifurcated, including: multiple subscriber equipmenies (UE) sharing described called public user identity reply response message to described caller, set up dialogue between described caller respectively；

The plurality of dialogue is carried out simultaneously the renewal of media resource, including: described call anchoring to grappling and after associated application server (SCCAS) receives the handover request of the described switching sent from mobile switching centre, finding the plurality of dialogue, the called UE of each dialogue wherein initiates far-end more new technological process respectively in a parallel fashion.

Preferably, described method also includes after also having a characteristic that the renewal that the plurality of dialogue carries out media resource simultaneously:

After described SCCAS receives the renewal response of described each dialogue, reply switching response according to described renewal response to described mobile switching centre；

After in the plurality of dialogue, the called UE of certain dialogue first carries out off-hook response, described off-hook response is transmitted to described caller through described mobile switching centre by described SCCAS, connects described dialogue in CS territory.

Preferably, described method also includes after also having a characteristic that the renewal that the plurality of dialogue carries out media resource simultaneously:

Described SCCAS receives the renewal response of one or more dialogues in the plurality of dialogue, renewal response according to the first dialogue received at first replys switching response to described mobile switching centre, and what preserve other dialogues updates response message and the corresponding relation with affiliated dialogue thereof；

When the called UE of described first dialogue first carries out off-hook response, described off-hook response is directly transmitted to described caller through described mobile switching centre by described SCCAS, connects described first dialogue in CS territory；

When in the plurality of dialogue, the called UE of another dialogue first carries out off-hook response, described SCCAS first finds the renewal response message of another dialogue described, initiate to update conversation process to described mobile switching centre according to Session Description Protocol therein (SDP) information, after completing the media renewal of another dialogue described, described off-hook response is transmitted to described caller through described mobile switching centre, connects another dialogue described in CS territory.

Preferably, described method also has a characteristic that

After described mobile switching centre receives the described SCCAS switching response replied, the also resource in the reserved PS territory of dialogue belonging to described switching response.

Preferably, described method also has a characteristic that the described response producing multiple dialogues due to callee side bifurcated, including: called network adopts bifurcated (forking) pattern to provide CRBT, and the Ring Back Tone service of described called UE and described called network provides server (CATAS) all reply response message to described caller and set up dialogue respectively；

The plurality of dialogue is carried out simultaneously the renewal of media resource, including: described call anchoring to SCCAS receive the handover request of the described switching sent from mobile switching centre after, find the plurality of dialogue, initiate far-end more new technological process respectively to described CATAS and described called UE in a parallel fashion.

Preferably, described method also includes after also having a characteristic that the renewal that the plurality of dialogue carries out media resource simultaneously:

After described SCCAS receives the renewal response of described CATAS, the the first switching response carrying CRBT media resource information is replied to described mobile switching centre, after described mobile switching centre receives the first switching response, the CS for the session establishment CRBT media between described CATAS and caller connects；

After described SCCAS receives the renewal response of described called UE, the the second switching response carrying normal media resource information is replied to described mobile switching centre, after described mobile switching centre receives the second switching response, postpone the CS for the session establishment normal media between described called UE and caller and connect；

After described mobile switching centre receives the off-hook response of described called UE, the CS disconnecting described CRBT media connects, and the CS setting up described normal media connects.

Preferably, described method also includes after also having a characteristic that the renewal that the plurality of dialogue carries out media resource simultaneously:

Described first switching response and the second switching response also carry early media (P-Early-Media) header field, the two switching response is carried morning media header field value different；

According to the value switching early media header field in response received, described mobile switching centre judges that described switching response is the first switching response or the second switching response.

A kind of cross-domain switched system of the calling based on IP Multimedia System, including grappling and associated application server (SCCAS) and mobile switching centre:

Described SCCAS includes:

Anchoring system, in caller in called initiation call request procedure, detecting when callee side bifurcated produces multiple dialogue, the information of calling and the plurality of dialogue described in grappling；

Hand-off process module, includes again: media updating block, for, after receiving the handover request that described mobile switching centre sends, the plurality of dialogue carrying out the renewal of media resource simultaneously.

Described mobile switching centre includes:

Handover request module, for when caller is initiated from packet domain exchange network (PS) territory to the switching in circuit domain exchange network (CS) territory, sending handover request to SCCAS.

Preferably, described system also has a characteristic that the plurality of dialogue of described anchoring system grappling includes the dialogue between described caller and the multiple subscriber equipmenies (UE) sharing described called public user identity；

The media updating block of described hand-off process module finds the plurality of dialogue after receiving described handover request, and the called UE of each dialogue wherein initiates far-end more new technological process respectively in a parallel fashion.

Preferably, described system also has a characteristic that described hand-off process module also includes:

First response unit, for, after the renewal response receiving described each dialogue, replying switching response according to described renewal response to described mobile switching centre；

Second response unit, for after the off-hook response of certain dialogue, being forwarded to described mobile switching centre in receiving the plurality of dialogue；

Described mobile switching centre also includes:

Resource reservation module, for after receiving the described SCCAS switching response replied, the resource in PS territory is reserved in the dialogue belonging to described switching response；

Call through module, for, after receiving the described SCCAS described off-hook response forwarded, connecting the dialogue belonging to described off-hook response in CS territory.

Preferably, described system also has a characteristic that

Described hand-off process module also includes:

First response unit, for receiving the renewal response of one or more dialogues in the plurality of dialogue, renewal response according to the first dialogue received at first replys switching response to described mobile switching centre, and what preserve other dialogues updates response message and the corresponding relation with affiliated dialogue thereof；

Second response unit, and in receiving the plurality of dialogue after the off-hook response of a dialogue, dialogue as described in judging for as described in first talk with, directly described off-hook response is forwarded to described mobile switching centre, otherwise, first find the renewal response message of described dialogue, Session Description Protocol (SDP) according in described renewal response message) information to described mobile switching centre initiate update conversation process, after completing the media renewal of described dialogue, more described off-hook response is forwarded to described mobile switching centre；

Described mobile switching centre also includes:

Resource reservation module, for after receiving the described SCCAS switching response replied, the resource in PS territory is reserved in the dialogue belonging to described switching response；

Talk with more new module, for coordinating with described SCCAS, it is achieved the media of dialogue update；

Call through module, for, after receiving the described SCCAS described off-hook response forwarded, connecting the dialogue belonging to described off-hook response in CS territory.

Preferably, described system also has a characteristic that

The plurality of dialogue of described anchoring system grappling includes the Ring Back Tone service of described calling and called network provides the dialogue between server (CATAS) and the dialogue between described calling and called UE；

The media updating block of described hand-off process module finds the plurality of dialogue after receiving described handover request, initiates far-end more new technological process respectively to described CATAS and called UE in a parallel fashion.

Preferably, described system also has a characteristic that described hand-off process module also includes:

First response unit, for, after the renewal response receiving described CATAS, replying the first switching response carrying CRBT media resource information to described mobile switching centre；After receiving the renewal response of described called UE, reply the second switching response carrying normal media resource information to described mobile switching centre；

Second response unit, for, after the off-hook response receiving described called UE, being forwarded to described mobile switching centre；

Described mobile switching centre also includes:

Connection establishment module, for after receiving the first switching response, the CS for the session establishment CRBT media between described CATAS and caller connects；After receiving the second switching response, postpone the CS for the session establishment normal media between described called UE and caller and connect；And, after the off-hook response receiving described called UE, the CS disconnecting described CRBT media connects, and the CS setting up described normal media connects.

Preferably, described system also has a characteristic that

Described connection establishment module is to judge that described switching response is the first switching response or the second switching response according to the value switching early media header field in response received.

Embodiment provided by the invention, when occurring from PS network to the switching of CS network, simultaneously complete due to the forking renewal to multiple dialogues produced, thus not affecting normal call request, and existing IMS architecture need not be made an amendment, simple, without being triggered by initiating the mode of handover request by calling subscribe, simplify media resource more new technological process, solve the problem that in prior art, media resource more new technological process is lengthy and tedious, improve media resource and update efficiency.

Accompanying drawing explanation

Fig. 1 is the structural representation switched in IP Multimedia System in prior art；

The Fig. 2 (a) and Fig. 2 (b) flow chart for ongoing calling being switched in IP Multimedia System in prior art；

Fig. 3 (a) and Fig. 3 (b) in IP Multimedia System in prior art for ongoing calling, when the called scene having forking, and system does not support the mid-call flow chart switched；

Fig. 4 (a), Fig. 4 (b) and Fig. 4 (c) in IP Multimedia System in prior art for ongoing calling, have a forking when called, and flow chart when system supports mid-call switching；

Fig. 5 (a), 5 (b) and Fig. 5 (c) are the schematic flow sheet of first embodiment of the invention method；

Fig. 6 is for providing the schematic flow sheet of Ring Back Tone service in IP Multimedia System in prior art；

The schematic flow sheet that Fig. 7 (a) and Fig. 7 (b) is third embodiment of the invention method；

The schematic flow sheet that Fig. 8 (a), Fig. 8 (b) and Fig. 8 (c) are second embodiment of the invention method；

Fig. 9 is the structural representation of the cross-domain switched system main network elements of fifth embodiment of the invention；

Figure 10 is the structural representation of the cross-domain switched system main network elements of sixth embodiment of the invention.

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearly, the present invention is described in further detail below in conjunction with the accompanying drawings and the specific embodiments.It should be noted that when not conflicting, the embodiment in the application and the feature in embodiment can combination in any mutually.

Embodiment one

The method flow schematic diagram managing media resource in the ip multimedia subsystem that Fig. 5 (a) and Fig. 5 (b) provides for application example of the present invention.In Fig. 5, calling UE A initiates call request to called subscriber, multiple UE is had to share same PUI (PublicUseridentity common user's sign) due to called, now the call request of caller can be sent respectively to each UE by IMS network element, thus in call establishment, establishing the dialogue to multiple UE, in calling procedure, calling UE A meets the switching condition being switched to CS territory from PS territory.In as above application scenarios, a dialogue (dialogue 1) is produced between UEA and UE#2, producing another dialogue (dialogue 2) between UEA and UE#3, wherein dialogue sign is to indicate (Fromtag), recipient's sign (Totag) and calling ID (callID) three according to initiator to together decide on.Idiographic flow is as shown in Figure 5:

501～516, calling UE A sends one request of calling, due to called forking, produces 2 dialogues, dialogue 1 and dialogue 2, and its flow process is identical with in Fig. 3 301～316；

517, calling UE A meets switching condition, MSCserver initiate handover request to IMS network；

518～518a, after SCCAS receives handover request, search this user now ongoing dialogue, when judging that UEA now exists an ongoing calling, and owing to forking creates multiple dialogue (in this example the dialogue of 2, position), then initiate far-end to the called UE of each dialogue more newly requested simultaneously；

The multiple dialogues all identical with calling ID are indicated, so SCCAS may determine that called generation forking produces multiple dialogues owing to Calling Side has initiator.

519～526, namely complete the far-end more new technological process of dialogue 1, its flow process is with 319～326 in Fig. 3；

527～534, SCCAS notifies that this session of MSCserver is an ongoing calling, and its flow process is with 327～334 in Fig. 3；This flow process is to trigger after MSCserver receives switching response；

535～542, carry out with 519 steps simultaneously, SCCAS also initiates the far-end more new technological process of dialogue 2 to UE#3, and its flow process is similar with 519～526, is distinctive in that the sending object of SCCAS is UE#3；

Now namely complete the renewal process to each dialogue that forking produces.

543a～552a, if now UE#2 first replys, then completes response by the more new route talking with 1 before, connects dialogue 1 in CS territory, and dialogue 2 is discharged；

543b～552b, if now UE#3 first replys, then completes response by the more new route talking with 2 before, connects dialogue 2 in CS territory, and dialogue 1 is discharged；

It can be seen that for ongoing calling, there is forking when called from above example, when calling terminal produces multiple dialogue, by this switching flow, it is possible to each dialogue is switched over simultaneously, no matter which terminal of callee side has connected this calling can ensure the success of calling.

Embodiment two

The schematic flow sheet that Fig. 8 (a), Fig. 8 (b) and Fig. 8 (c) are second embodiment of the invention method, this embodiment two is called another embodiment when having a forking.

The present embodiment and embodiment one main difference is that the SCCAS handover request receiving MSCSERVER after, or it is more newly requested to send far-end with forking to the called UE of each dialogue, but SCCAS only sends switching response according to one of them more should reply (renewal response of the dialogue such as received at first) talking with (being designated as the first dialogue) to MSCSERVER, being preserved by the response message of more answering of all the other dialogues, these update response message and need to be associated with the ID of affiliated dialogue.

If the called UE of certain dialogue follow-up have answered this calling (sending 200OK response message), but this dialogue is not the first dialogue, then SCCAS dialogue belonging to this 200OK response finds what preserve before more to answer response message, and use this more to answer response message to initiate to update conversation process to MSCSERVER, after the media of this dialogue have updated, then the 200OK of called party answer is transmitted to caller by MSCSERVER.MSCSERVER connects this dialogue in CS territory.If this dialogue is the first dialogue, SCCAS need not initiate dialogue and update, and directly by SERVER, this 200OK response is transmitted to caller, connects this first dialogue in CS territory.

In the present embodiment, MSCSERVER need not have the ability of the resource in the reserved PS territory of multiple dialogues for same session, has saved resource simultaneously.

801～816, calling UE A sends one request of calling, due to called forking, produces 2 dialogues, dialogue 1 and dialogue 2, and its flow process is identical with in Fig. 3 301～316；

817, calling UE A meets switching condition, MSCserver initiate handover request to IMS network；

818～818a, after SCCAS receives handover request, search this user now ongoing dialogue, when judging that UEA now exists an ongoing calling, and owing to forking creates multiple dialogue (in this example the dialogue of 2, position), then initiate far-end to each dialogue more newly requested simultaneously；

819～826, even if completing the far-end more new technological process of dialogue 1, its flow process is with 319～326 in Fig. 3；

827～834, SCCAS notifies that this session of MSCserver is an ongoing calling, and its flow process is with 327～334 in Fig. 3；

835～840, carry out with 519 steps simultaneously, SCCAS also initiates the far-end more new technological process of dialogue 2 to UE#3, and its flow process is similar with 519～524；

841, now the renewal response of this forking branch is not forwarded by SCCAS to MSCserver, but preserves this response, and the dialogue ID produced when being set up with this branch by this response (talks with ID to include, call-ID, fromtag, the totag of dialogue) it is associated；

842a～851a, if now UE#2 first replys, then completes response by the more new route talking with 1 before, connects dialogue 1 in CS territory, and dialogue 2 is discharged；

843b～844b, if now UE#3 first replys, then this 200OK response can be sent to SCCAS；

After 845b～846b, SCCAS receive this 200OK, according to its dialogue id information, find the response message that 841 steps preserve, and by the SDP information in this response, initiate to update session request to MSCserver；

847b～848b, MSCserver, according to the new SDP information received, reply and update response；

849b～851b, now SCCAS new more should the replying received sends more newly requested to remote subscriber, and what now update is the SDP information in dialogue 2；

852b～854b, far-end, according to new Session Description Protocol (SDP) information, is replied and is updated response；

855b～856b, after renewal completes, the 200OK response being previously received is sent to UEA by SCCAS again；

After 857b, MSCserver receive 200OK, convert the ANM in CS territory to, be sent to UEA；

858b～859b, MSCserver, after receiving 200OK, reply ACK to UE3；

860b～861b, called IMS network element, terminate dialogue 1 by prior art；

It can be seen that for ongoing calling, there is forking when called from above example, when calling terminal produces multiple dialogue, by this switching flow, it is possible to each dialogue is switched over simultaneously, no matter which terminal of callee side has connected this calling can ensure the success of calling.

Embodiment three

Present disclosure additionally applies for called there is no forking but use bifurcated (forking) technology coloring ring back tone playing situation；

Fig. 6 is the flow chart schematic diagram adopting bifurcated (forking) technology coloring ring back tone playing in prior art, specifically includes:

601, the user equipment (UE) 1 of caller is initiated one and is risen and call for and ask, and carries the media resource information of UE1, through Calling Side IMS network element；

602, Calling Side S-CSCF network element will be called for and ask and be sent to callee side S-CSCF network element；

603, call request is routed to the Ring Back Tone service of called network and provides on server (CATAS) by callee side S-CSCF network element；

Call request is sent to called subscriber UE2 again through callee side S-CSCF network element by 604, CATAS；

605, CATAS adopt dialogue 2 to UE1 to send calls for the response message asked, and carries CRBT media information, message travels callee side S-CSCF network element；

606～607, the CATAS response message sent is forwarded to calling UE 1 by Calling Side S-CSCF network element by callee side S-CSCF network element, makes UE1 and CATAS consult the media resource providing Ring Back Tone service；

After CRBT media negotiation is good, CATAS can be just calling subscribe's coloring ring back tone playing media.Here for simplification, it is assumed that the negotiation of media once just can complete, if needing to do resource reservation or media once consult not success, it is possible to carry out repeatedly the negotiation of media resource between calling subscribe and CATAS.

608, owing to there occurs (forking) bifurcated, UE2 adopts dialogue 1 also to send to UE1 and calls for the response message asked, and carries the UE2 media resource information for normal talking, message travels originating S-CSCF network element arrives UE1, makes UE1 and UE2 consult the media resource of normal talking；

609, called this calling is carried out response, 200OK response message can be sent to CATAS by callee side S-CSCF network element；

610, CATAS receive this 200OK response after, terminate coloring ring back tone playing media；

611～613, CATAS passes through callee side S-CSCF network element and Calling Side S-CSCF network element, and 200OK response is sent to calling subscribe UE1；

614～617, after calling subscribe receives 200OK response, namely this call request calculates connection, returns ACK to called calling UE 2 simultaneously and confirms.

More than adopt the example of bifurcated (forking) technology coloring ring back tone playing exactly, in from the example above, can be seen that, this call session comprises two dialogues, one between CATAS and the subscriber equipment of caller about the dialogue of CRBT, another is the dialogue consulted about the normal media that calling is required between calling subscribe and called subscriber.And the two dialogue all should be set up before 200OK response.

Wen Zhong, produces multiple dialogues by called generation forking, and called employing (forking) bifurcated technology is that caller coloring ring back tone playing produces multiple dialogue, be referred to as callee side bifurcated and produce multiple dialogues.

For such call request, namely time called employing (forking) bifurcated technology is caller coloring ring back tone playing, when, before 200OK, the subscriber equipment of caller there occurs the change of position, and triggering the switching of PS to CS, situation now can switch over by the technology of the present invention.

Method shown in the method flow schematic diagram managing media resource in the ip multimedia subsystem that Fig. 7 (a) and Fig. 7 (b) provides for embodiment two, Fig. 7 (a) and Fig. 7 (b) specifically includes:

701, the user equipment (UE) 1 of caller is initiated one and is risen and call for and ask, and carries the media resource information of UE1, message travels S-CSCF；

702, S-CSCF will call for ask and be forwarded on SCCAS；

703, SCCAS will call for ask and carry out grappling；

704, SCCAS will call for again ask and be sent to S-CSCF；

705, S-CSCF will call for ask and be routed to called subscriber's network, by called subscriber's forwarded to CATAS；

Call request is sent to called user equipment (UE) 2 again through called network by 706, CATAS；

707, called UE 2 has received to call for and has asked, send and exhaled response, the media resource information carrying UE2 user's normal talking (is called the normal media consultation and dialogue of UE2, adopt dialogue 1), SCCAS exhales response message to be forwarded to calling UE 1 by rising of being sent by UE2 of the S-CSCF of caller network, and the information talking with 1 is anchored on SCCAS；

708, CATAS has received to call for and has asked simultaneously, and find that Ring Back Tone service is supported in caller, use dialogue 2 to reply to calling UE 1 and exhale response message, carry CRBT media resource information, the response that CATAS sends is talked with 2 information to being forwarded to calling UE 1 by the S-CSCF of caller network by SCCAS, and the information of dialogue 2 is also anchored on SCCAS；

709, calling subscribe position changes, and meet switching condition, MSCSERVER sends handover request to IMS network, carry the media resource information of MSCSERVER (owing to being used for being connected with CS media, it is called CS media resource information), if and MSCSERVER supports the broadcasting of (earlymedia) early media, band is then supported the sign (namely carrying early media (P-Early-Media) header field) of early media in handover request, if its value is supported)；

Handover request is forwarded to SCCAS by 710, S-CSCF；

711, SCCAS receives above-mentioned handover request, the session finding an activated state switches over, it namely it is here this ongoing call request session, and find in the session that calling subscribe carries out due to (forking) bifurcated, have received two dialogues, consult for CRBT for one, another is for the negotiation of normal media；SCCAS now adopts (forking) bifurcated technology, far-end is initiated respectively more newly requested to CATAS and called subscriber UE2, here the 711st step is that the SCCAS dialogue 2 to CRBT media sends more newly requested, wherein carry CRBT media SDP Request, comprise the CRBT media information consulted before, but media parameter changes into the MSCSERVER media parameter provided, and also the upper MSCSERVER of band supports the parameter of (earlymedia) early media；

712～713, CATAS receive dialogue 2 (CRBT media dialog) more newly requested after, return to SCCAS and update response, wherein carry CRBT media resource information, and it is with upper P-Early-Media header field, if its value is sendrecv or sendonly, but not unless adopted the possibility of other values, complete the renewal of CRBT media.

713, SCCAS receive renewal response after, to S-CSCF return handover request response (also referred to as switching response), this response can be denoted as response 1, wherein carrying CRBT media resource information, and also brought by P-Early-Media header field, its value is set to sendrecv or sendonly；

714～716, the handover request response of reception is forwarded to MSCserver by S-CSCF.After MSCserver receives this switching response, namely complete the renewal of CRBT dialogue；

717, MSCserver judges P-Early-Media header field simultaneously, if its value is sendrecv or sendonly, then sends CS Ringing message at CS network and continues as user in CS territory coloring ring back tone playing.

718～725, it is the flow process that the SCCAS session telling MSCserver currently to switch is an ongoing ringing-state session；

726, while 711 steps send, SCCAS also sends the more newly requested of dialogue 1 to called subscriber UE2, wherein carries normal media SDP Request, comprise the normal media information consulted before, but the media parameter in this step is the MSCserver media parameter provided；

727～728, the more newly requested of dialogue 1 is sent to called subscriber UE2 by called network；

729～730, called subscriber UE2 replys and updates response, including normal media SDP response, and carries P-Early-Media header field, owing to this response is not intended to consult CRBT media, so its value is set to inactive；

731, this renewal response is sent to SCCAS by called network；

732～733, this renewal response is sent to MSCSERVER, the handover request of corresponding 710th step with handover request response by SCCAS, this response can be denoted as response 2, what wherein carry is the media information of normal media, also carries P-Early-Media header field, and its value is set to inactive, after MSCSERVER receives this response, judge P-Early-Media header field, if its value is inactive, be not first that this session establishment CS connects, here namely, it is not first that normal media session establishment CS connects；

This step can be postpone the resource for the reserved PS territory of normal media dialogue, but postpones connecting for normal media session establishment CS.

734, this calling of called subscriber answer, corresponding dialogue 2, send 200OK response to calling subscribe；

735, CATAS receive 200OK response after, terminate CRBT media broadcasting；

736～738, called network is by before to the more new technological process talking with 2,200OK response is sent to MSCSERVER, after MSCSERVER receives 200OK, the CS of previously established CRBT media is connected, namely dialogue 2 disconnects with the corresponding relation of CS link, and the CS simultaneously setting up normal media connects, and namely sets up the dialogue 1 corresponding relation with CS link；

739, MSCSERVER the CS link establishment of normal media is completed after, to calling subscribe UE1 send CS signaling ANM, tell calling subscribe that UE1 the other side has answered that, it is possible to start call；

740～743, MSCSERVER sends to called subscriber UE2 and confirms ACK simultaneously.

Now whole switching just completes.

Embodiment four

Set up in calling procedure in calling and called, if there being multiple subscriber equipment to share called public user identity, and wherein have subscriber equipment signing to have Ring Back Tone service, then callee side also can occur forking to produce multiple dialogues, wherein said multiple dialogue includes the CATCS of the subscriber equipment place network of dialogue (referred to as Class1) and the signing Ring Back Tone service set up between each subscriber equipment and the caller dialogue (type 2) set up with caller, so when the switching in caller generation PS territory to CS territory, it is also desirable to the plurality of dialogue is updated simultaneously.Wherein the renewal of the dialogue of Class1 can be processed referring to the method for embodiment one, the renewal of the dialogue of type 2 can be processed referring to the method for embodiment two.

In sum, when occurring from PS network to the switching of CS network, simultaneously complete due to the forking renewal to multiple dialogues produced, thus not affecting normal call request, and existing IMS architecture need not be made an amendment, simple, without being triggered by initiating the mode of handover request by calling subscribe, simplify media resource more new technological process, solve the problem that in prior art, media resource more new technological process is lengthy and tedious, improve media resource and update efficiency.Present invention could apply to the switching of SRVCC.

Embodiment five

The present embodiment provides the cross-domain switched system of a kind of calling based on IP Multimedia System, including the network shown in Fig. 1, when realizing the present invention, it is necessary to according to the method in embodiment one or embodiment two, the function of SCCAS and MSCserver is strengthened.

As it is shown in figure 9, in the present embodiment, described SCCAS includes:

Anchoring system, in caller in called initiation call request procedure, detecting when callee side bifurcated produces multiple dialogue, the information of calling and the plurality of dialogue described in grappling；Specifically, the plurality of dialogue includes the dialogue between described caller and the multiple subscriber equipmenies (UE) sharing described called public user identity；

Hand-off process module, includes again: media updating block, for, after receiving the described MSCserver handover request sent, the plurality of dialogue carrying out the renewal of media resource simultaneously.Specifically, after receiving described handover request, finding the plurality of dialogue, the called UE of each dialogue wherein initiates far-end more new technological process respectively in a parallel fashion.

Described MSCserver includes:

Handover request module, for when caller is initiated from packet domain exchange network (PS) territory to the switching in circuit domain exchange network (CS) territory, sending handover request to SCCAS.

If adopting the cross-domain changing method in embodiment one:

Described hand-off process module also includes:

First response unit, for, after the renewal response receiving described each dialogue, replying switching response according to described renewal response to described MSCserver；

Second response unit, for after the off-hook response of certain dialogue, being forwarded to described MSCserver in receiving the plurality of dialogue；

Described MSCserver also includes:

Resource reservation module, for after receiving the described SCCAS switching response replied, the resource in PS territory is reserved in the dialogue belonging to described switching response；

Call through module, for, after receiving the described SCCAS described off-hook response forwarded, connecting the dialogue belonging to described off-hook response in CS territory.

If adopting the cross-domain changing method in embodiment two:

Described hand-off process module also includes:

First response unit, for receiving the renewal response of one or more dialogues in the plurality of dialogue, renewal response according to the first dialogue received at first replys switching response to described MSCserver, and what preserve other dialogues updates response message and the corresponding relation with affiliated dialogue thereof；

Second response unit, and in receiving the plurality of dialogue after the off-hook response of a dialogue, dialogue as described in judging for as described in first talk with, directly described off-hook response is forwarded to described MSCserver, otherwise, first find the renewal response message of described dialogue, Session Description Protocol (SDP) according in described renewal response message) information to described MSCserver initiate update conversation process, after completing the media renewal of described dialogue, more described off-hook response is forwarded to described MSCserver；

Described MSCserver also includes:

Resource reservation module, for after receiving the described SCCAS switching response replied, the resource in PS territory is reserved in the dialogue belonging to described switching response；

Talk with more new module, for coordinating with described SCCAS, it is achieved the media of dialogue update；

Call through module, for, after receiving the described SCCAS described off-hook response forwarded, connecting the dialogue belonging to described off-hook response in CS territory.

Embodiment five

The present embodiment provides the cross-domain switched system of a kind of calling based on IP Multimedia System, including the network shown in Fig. 1, when realizing the present invention, it is necessary to according to the method in embodiment three, the function of SCCAS and MSCserver is strengthened.

As shown in Figure 10, in the present embodiment, described SCCAS includes:

Anchoring system, in caller in called initiation call request procedure, detecting when callee side bifurcated produces multiple dialogue, the information of calling and the plurality of dialogue described in grappling；Specifically, the plurality of dialogue includes the dialogue between Ring Back Tone service offer server (CATAS) of described calling and called network and the dialogue between described calling and called UE；

Hand-off process module, includes again: media updating block, for, after receiving the described MSCserver handover request sent, the plurality of dialogue carrying out the renewal of media resource simultaneously.Specifically, after receiving described handover request, find the plurality of dialogue, initiate far-end more new technological process respectively to described CATAS and called UE in a parallel fashion.

Described MSCserver includes:

Handover request module, for when caller is initiated from packet domain exchange network (PS) territory to the switching in circuit domain exchange network (CS) territory, sending handover request to SCCAS.

Further, described hand-off process module also includes:

First response unit, for, after the renewal response receiving described CATAS, replying the first switching response carrying CRBT media resource information to described MSCserver；After receiving the renewal response of described called UE, reply the second switching response carrying normal media resource information to described MSCserver；

Second response unit, for, after the off-hook response receiving described called UE, being forwarded to described MSCserver；

Described MSCserver also includes:

Connection establishment module, for after receiving the first switching response, the CS for the session establishment CRBT media between described CATAS and caller connects；After receiving the second switching response, postpone the CS for the session establishment normal media between described called UE and caller and connect；And, after the off-hook response receiving described called UE, the CS disconnecting described CRBT media connects, and the CS setting up described normal media connects.Specifically, according to the value switching early media header field in response received, described connection establishment module can judge that described switching response is the first switching response or the second switching response.

In sum, system provided by the invention, when occurring from PS network to the switching of CS network, simultaneously complete due to the forking renewal to multiple dialogues produced, thus not affecting normal call request, and existing IMS architecture need not be made an amendment, simple, it is not necessary to be triggered by initiating the mode of handover request by calling subscribe, simplify media resource more new technological process, solve the problem that in prior art, media resource more new technological process is lengthy and tedious, improve media resource and update efficiency.

One of ordinary skill in the art will appreciate that all or part of step of above-described embodiment can use computer program flow process to realize, described computer program can be stored in a computer-readable recording medium, described computer program performs (such as system, unit, device etc.) on corresponding hardware platform, upon execution, including step of embodiment of the method one or a combination set of.

Alternatively, all or part of step of above-described embodiment can also use integrated circuit to realize, and these steps can be fabricated to integrated circuit modules one by one respectively, or the multiple modules in them or step are fabricated to single integrated circuit module realize.So, the present invention is not restricted to the combination of any specific hardware and software.

Each device/functional module/functional unit in above-described embodiment can adopt general calculation element to realize, and they can concentrate on single calculation element, it is also possible to is distributed on the network that multiple calculation element forms.

When each device/functional module/functional unit in above-described embodiment is using the form realization of software function module and as independent production marketing or use, it is possible to be stored in a computer read/write memory medium.Computer read/write memory medium mentioned above can be read only memory, disk or CD etc..

The above; being only the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, any those familiar with the art is in the technical scope that the invention discloses; change can be readily occurred in or replace, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain described in claim.

Claims (15)

1. based on a cross-domain changing method for the calling of IP Multimedia System, including:

In caller in the call request procedure of called initiation, callee side bifurcated forking produces the response of multiple dialogues；

In described call request procedure, if the switching from packet switched ps domain to circuit-switched CS domain is initiated in described caller, the plurality of dialogue is carried out simultaneously the renewal of media resource；

Wherein, the plurality of dialogue is carried out simultaneously the renewal of media resource, including: described call anchoring to grappling and after associated application server S CCAS receives the handover request of the described switching sent from mobile switching centre, finding the plurality of dialogue, the called UE of each dialogue wherein initiates far-end more new technological process respectively in a parallel fashion.

2. method according to claim 1, it is characterised in that:

Described callee side bifurcated produces the response of multiple dialogues, including: multiple user equipment (UE)s sharing described called public user identity reply response message to described caller, set up dialogue between described caller respectively.

3. method according to claim 2, it is characterised in that after the plurality of dialogue is carried out simultaneously the renewal of media resource, also include:

After described SCCAS receives the renewal response of described each dialogue, reply switching response according to described renewal response to described mobile switching centre；

After in the plurality of dialogue, the called UE of certain dialogue first carries out off-hook response, described off-hook response is transmitted to described caller through described mobile switching centre by described SCCAS, connects described dialogue in CS territory.

4. method according to claim 2, it is characterised in that after the plurality of dialogue is carried out simultaneously the renewal of media resource, also include:

Described SCCAS receives the renewal response of one or more dialogues in the plurality of dialogue, renewal response according to the first dialogue received at first replys switching response to described mobile switching centre, and what preserve other dialogues updates response message and the corresponding relation with affiliated dialogue thereof；

When the called UE of described first dialogue first carries out off-hook response, described off-hook response is directly transmitted to described caller through described mobile switching centre by described SCCAS, connects described first dialogue in CS territory；

When in the plurality of dialogue, the called UE of another dialogue first carries out off-hook response, described SCCAS first finds the renewal response message of another dialogue described, initiate to update conversation process to described mobile switching centre according to Session Description Protocol SDP information therein, after completing the media renewal of another dialogue described, described off-hook response is transmitted to described caller through described mobile switching centre, connects another dialogue described in CS territory.

5. the method according to claim 3 or 4, it is characterised in that:

After described mobile switching centre receives the described SCCAS switching response replied, the also resource in the reserved PS territory of dialogue belonging to described switching response.

6. method according to claim 1, it is characterised in that:

Described callee side bifurcated produces the response of multiple dialogues, including: called network adopts bifurcated forking pattern to provide CRBT, and the Ring Back Tone service of described called UE and described called network provides server CATAS all reply response message to described caller and set up dialogue respectively；

The plurality of dialogue is carried out simultaneously the renewal of media resource, including: described call anchoring to SCCAS receive the handover request of the described switching sent from mobile switching centre after, find the plurality of dialogue, initiate far-end more new technological process respectively to described CATAS and described called UE in a parallel fashion.

7. method according to claim 6, it is characterised in that after the plurality of dialogue is carried out simultaneously the renewal of media resource, also include:

After described SCCAS receives the renewal response of described CATAS, the the first switching response carrying CRBT media resource information is replied to described mobile switching centre, after described mobile switching centre receives the first switching response, the CS for the session establishment CRBT media between described CATAS and caller connects；

After described SCCAS receives the renewal response of described called UE, the the second switching response carrying normal media resource information is replied to described mobile switching centre, after described mobile switching centre receives the second switching response, postpone the CS for the session establishment normal media between described called UE and caller and connect；

After described mobile switching centre receives the off-hook response of described called UE, the CS disconnecting described CRBT media connects, and the CS setting up described normal media connects.

8. method according to claim 7, it is characterised in that after the plurality of dialogue is carried out simultaneously the renewal of media resource, also include:

Described first switching response and the second switching response also carry early media P-Early-Media header field, two kinds of switching responses are carried morning media header field value different；

According to the value switching early media header field in response received, described mobile switching centre judges that described switching response is the first switching response or the second switching response.

9. based on a cross-domain switched system for the calling of IP Multimedia System, including grappling and associated application server S CCAS and mobile switching centre, it is characterised in that:

Described SCCAS includes:

Anchoring system, in caller in called initiation call request procedure, detecting when callee side bifurcated produces multiple dialogue, the information of calling and the plurality of dialogue described in grappling；

Hand-off process module, includes again: media updating block, for, after receiving the handover request that described mobile switching centre sends, the plurality of dialogue carrying out the renewal of media resource simultaneously；

Described mobile switching centre includes:

Handover request module, for when caller is initiated from packet domain exchange network PS territory to the switching in circuit domain exchange network CS territory, sending handover request to SCCAS；

Wherein, media updating block for, after receiving the handover request that described mobile switching centre sends, carrying out the renewal of media resource, specifically include simultaneously to the plurality of dialogue:

Described media updating block, after being used for receiving described handover request, finds the plurality of dialogue, and the called UE of each dialogue wherein initiates far-end more new technological process respectively in a parallel fashion.

10. cross-domain switched system according to claim 9, it is characterised in that:

The plurality of dialogue of described anchoring system grappling includes the dialogue between described caller and the multiple user equipment (UE)s sharing described called public user identity.

11. cross-domain switched system according to claim 10, it is characterised in that:

Described hand-off process module also includes:

First response unit, for, after the renewal response receiving described each dialogue, replying switching response according to described renewal response to described mobile switching centre；

Second response unit, for after the off-hook response of certain dialogue, being forwarded to described mobile switching centre in receiving the plurality of dialogue；

Described mobile switching centre also includes:

Resource reservation module, for after receiving the described SCCAS switching response replied, the resource in PS territory is reserved in the dialogue belonging to described switching response；

Call through module, for, after receiving the described SCCAS described off-hook response forwarded, connecting the dialogue belonging to described off-hook response in CS territory.

12. cross-domain switched system according to claim 10, it is characterised in that:

Described hand-off process module also includes:

First response unit, for receiving the renewal response of one or more dialogues in the plurality of dialogue, renewal response according to the first dialogue received at first replys switching response to described mobile switching centre, and what preserve other dialogues updates response message and the corresponding relation with affiliated dialogue thereof；

Second response unit, and in receiving the plurality of dialogue after the off-hook response of a dialogue, dialogue as described in judging for as described in first talk with, directly described off-hook response is forwarded to described mobile switching centre, otherwise, first find the renewal response message of described dialogue, initiate to update conversation process to described mobile switching centre according to the Session Description Protocol SDP information in described renewal response message, after completing the media renewal of described dialogue, more described off-hook response is forwarded to described mobile switching centre；

Described mobile switching centre also includes:

Resource reservation module, for after receiving the described SCCAS switching response replied, the resource in PS territory is reserved in the dialogue belonging to described switching response；

Talk with more new module, for coordinating with described SCCAS, it is achieved the media of dialogue update；

Call through module, for, after receiving the described SCCAS described off-hook response forwarded, connecting the dialogue belonging to described off-hook response in CS territory.

13. cross-domain switched system according to claim 9, it is characterised in that:

The plurality of dialogue of described anchoring system grappling includes the Ring Back Tone service of described calling and called network provides the dialogue between server CATAS and the dialogue between described calling and called UE；

The media updating block of described hand-off process module finds the plurality of dialogue after receiving described handover request, initiates far-end more new technological process respectively to described CATAS and called UE in a parallel fashion.

14. cross-domain switched system according to claim 13, it is characterised in that:

Described hand-off process module also includes:

First response unit, for, after the renewal response receiving described CATAS, replying the first switching response carrying CRBT media resource information to described mobile switching centre；After receiving the renewal response of described called UE, reply the second switching response carrying normal media resource information to described mobile switching centre；

Second response unit, for, after the off-hook response receiving described called UE, being forwarded to described mobile switching centre；

Described mobile switching centre also includes:

Connection establishment module, for after receiving the first switching response, the CS for the session establishment CRBT media between described CATAS and caller connects；After receiving the second switching response, postpone the CS for the session establishment normal media between described called UE and caller and connect；And, after the off-hook response receiving described called UE, the CS disconnecting described CRBT media connects, and the CS setting up described normal media connects.

15. cross-domain switched system according to claim 14, it is characterised in that:

Described connection establishment module is to judge that described switching response is the first switching response or the second switching response according to the value switching early media header field in response received.