CN104205886A

CN104205886A - Method and apparatus for maintaining call continuity

Info

Publication number: CN104205886A
Application number: CN201380004729.XA
Authority: CN
Inventors: 贾毅刚; 何群
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2013-12-03
Filing date: 2013-12-03
Publication date: 2014-12-10
Also published as: WO2015081477A1

Abstract

The present invention discloses a method for maintaining call continuity, a user data server and a mobile switching center apparatus. The method comprises receiving routing request information sent by the mobile switching center apparatus, the routing request information carrying a user identification of UE; acquiring a switchover routing number associated with the user identification according to the user identification; sending a route replay message to the mobile switching center apparatus, the route replay message carrying the switchover routing number, the switchover routing number being used for enabling the mobile switching center apparatus to route a CS call of the UE to ATCF. With adoption of the method for maintaining call continuity, the user data server and the mobile switching center apparatus, the handoff delay can be shortened, and user experience is raised.

Description

Keep the method and apparatus of call continuity

Technical field

The present invention relates to the communications field, and more specifically, relate to the method, user data server and the switching center equipment that keep call continuity.

Background technology

Long Term Evolution (Long Term Evolution, LTE) voice (the Voice over LTE of carrying, VoLTE) be a kind of internet protocol multi-media sub-system (IP Multimedia Sub system that uses, IMS) network provides the technology of human communication on the wireless access of the pattern of full grouping, object is the voice technology that substitutes traditional circuit switching (Circuit Switching, CS) pattern in new wireless technology.Along with progressively surmounting voice, data business volume becomes the main flow of customer consumption, LTE etc.

Full grouping wireless network will progressively be deployed to meet people's demand.

But in practice process, a kind of new Radio Access Network can not complete overnight the coverage of traditional C/S access network in the time disposing, the scene that just exists LTE access network to dispose at the oceanic island of CS access network, and the piecewise continuous scene of LTE access network.In the time that user moves to the border of LTE covering in the speech business that uses VoLTE to provide, voice will interrupt, and make troubles to user.

Treat the voice continuity of scene in order to keep LTE and lower pair of CS access, third generation partner program (The3rd Generation Partnership Project, 3GPP) study and provide two wireless voice call continuitys (Dual Radio Voice Call Continuity, DRVCC) technical scheme.Its principle is, as continuous voice call (Voice Call Continuity, VCC) subscriber equipment (User Equipment, UE) detect need to access switching (Access Transfer) time, set up the new access leg in a road (Access Leg) by CS network, send call setup message to MSC, carry session Handover Number (Session Transfer Number, STN), MSC will call out invitation (INVITE) message and be routed to inquiry/service call session control function entity (Interrogating/Serving Call Session Control Function, I/SCSCF), I/SCSCF is routed to INVITE business coherence and continuity application server (Service Consistency and Continuity Application Server again, SCC AS).SCC AS completes the foundation of the access leg under CS network, by international integrated services digital network (the Integrated Services Digital Network of correlation travelling carriage, ISDN) number (Correlation Mobile Station International ISDN Number, C-MSISDN) be associated with original session, initiate distant end media and upgrade.After distant end media has been upgraded, SCC AS discharges original LTE access leg, and VCC UE switches to CS network insertion from LTE network.That is to say, in the time that VCC UE initiates DRVCC switching, MSC gives SCC AS by the mode of IMS centralized services (IMS Centralized Services, ICS) grappling by calling.Because SCC AS only provides signaling grappling, the not grappling of the medium surface of VCC UE.Therefore SCC AS need to initiate the media renewal of distance connection leg, and after distant end media has been upgraded, the media negotiation that SCC AS can notify MSC to complete CS access leg, is anchored on media in CS media gateway (Media Gateway, MGW).Upgrading in the process of distant end media, can introduce the longer media break time, cause handover delay longer, experience thereby affect user.

Summary of the invention

The embodiment of the present invention provides a kind of method, user data server and switching center equipment that keeps call continuity, can shorten handover delay, improves user and experiences.

First aspect, provides a kind of method that keeps call continuity, comprising:

Receive the route request information that switching center equipment sends, wherein, this route request information is carried the user ID of user equipment (UE);

Obtain the switching routing number of this user ID association according to this user ID;

Send route response message to this switching center equipment, this route response message is carried this switching routing number, this switching routing number for make this switching center equipment by the circuit switching (CS) call routing of this UE to accessing switching control function entity A TCF.

In the possible implementation of the first, this switching routing number is the number that the calling for this UE that distributes in the internet protocol multi-media sub-system IMS of this UE register flow path of this ATCF is switched.

In conjunction with the possible implementation of the first of first aspect, in the possible implementation of the second, before receiving the route request information of switching center equipment transmission, the method also comprises:

Anastomosing home location register HLR receives this switching routing number of business coherence and continuity application server SCC AS transmission and preserves this switching routing number in the IMS of this UE register flow path, wherein, this switching routing number is distributed in the IMS of this UE register flow path by this ATCF and passes to this SCC AS;

The switching routing number that obtains this user ID association according to this user ID, comprising:

This fusion HLR obtains according to this user ID this switching routing number that this fusion HLR preserves in the IMS of this UE register flow path.

In conjunction with the possible implementation of the first of first aspect, in the third possible implementation, before receiving the route request information of switching center equipment transmission, the method also comprises:

HLR receives this switching routing number that home subscriber server HSS sends and preserves this switching routing number in the IMS of this UE register flow path, and wherein, this switching routing number is distributed in the IMS of this UE register flow path by this ATCF and passes to this HSS;

This HLR obtains according to this user ID this switching routing number that this HLR preserves in the IMS of this UE register flow path.

In conjunction with any the possible implementation in first to three kind of possible implementation of first aspect or first aspect, in the 4th kind of possible implementation, this route request information is also carried session Handover Number STN;

Before obtaining the switching routing number of this user ID association according to this user ID, the method also comprises:

Determine that according to this STN the CS of this UE calls out as the calling for switching.

In conjunction with any the possible implementation in first to fourth kind of first aspect or first aspect possible implementation, in the 5th kind of possible implementation, this switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.

Second aspect, provides a kind of method that keeps call continuity, comprising:

Send route request information to user data server, this route request information is carried the user ID of user equipment (UE);

Receive the route response message that this user data server sends, wherein, this route response message is carried the switching routing number of this user ID association, and this switching routing number is obtained according to this user ID by this user data server;

According to this switching routing number by the circuit switching (CS) call routing of this UE to accessing switching control function entity A TCF, the media that the CS of this UE is called out anchor to the access that this ATCF controls and switch on gateway A TGW.

In conjunction with the possible implementation of the first of second aspect, in the possible implementation of the second, this user data server is for merging HLR, and this switching routing number is preserved in the IMS of this UE register flow path by this fusion HLR.

In conjunction with the possible implementation of the first of second aspect, in the third possible implementation, this user data server is HLR, and this switching routing number is received and preserves from home subscriber server HSS in the IMS of this UE register flow path by this HLR.

In conjunction with any the possible implementation in first to three kind of possible implementation of second aspect or second aspect, in the 4th kind of possible implementation, before sending route request information to user data server, the method also comprises:

Receive the CS call setup message that this UE sends, this CS call setup message carries session Handover Number STN;

Send route request information to user data server, comprising:

Send this route request information to this user data server, this route request information is carried this STN and this user ID, so that this user data server determines that according to this STN the CS of this UE calls out as the calling for switching and obtains this switching routing number according to this user ID.

In conjunction with any the possible implementation in first to fourth kind of second aspect or second aspect possible implementation, in the 5th kind of possible implementation, this switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.

The third aspect, provides a kind of user data server, comprising:

Receiver module, the route request information sending for receiving switching center equipment, wherein, this route request information is carried the user ID of user equipment (UE);

Acquisition module, for obtaining the switching routing number of this user ID association according to this user ID;

Sending module, for sending route response message to this switching center equipment, this route response message is carried this switching routing number, this switching routing number for make this switching center equipment by the circuit switching (CS) call routing of this UE to accessing switching control function entity A TCF.

In conjunction with the possible implementation of the first of the third aspect, in the possible implementation of the second, this user data server is for merging HLR;

This receiver module also receives for the IMS register flow path at this UE this switching routing number that business coherence and continuity application server SCC AS sends, wherein, this switching routing number is distributed in the IMS of this UE register flow path by this ATCF and passes to this SCCAS;

This user data server also comprises:

The first memory module, for preserving this switching routing number;

This acquisition module this switching routing number specifically for preserving in the IMS register flow path obtaining at this UE according to this user ID.

In conjunction with the possible implementation of the first of the third aspect, in the third possible implementation, this user data server is that this receiver module of HLR also receives for the IMS register flow path at this UE this switching routing number that home subscriber server HSS sends, wherein, this switching routing number is distributed in the IMS of this UE register flow path by this ATCF and passes to this HSS;

This user data server also comprises:

The second memory module, for preserving this switching routing number;

In conjunction with any the possible implementation in first to three kind of possible implementation of the third aspect or the third aspect, in the 4th kind of possible implementation, this route request information that this receiver module receives is also carried session Handover Number STN;

This user data server also comprises:

Determination module, this STN carrying for this route request information receiving according to this receiver module determines that the CS of this UE calls out as the calling for switching.

In conjunction with any the possible implementation in first to fourth kind of the third aspect or the third aspect possible implementation, in the 5th kind of possible implementation, this switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.

Fourth aspect, provides a kind of switching center equipment, comprising:

Sending module, for sending route request information to user data server, this route request information is carried the user ID of user equipment (UE);

Receiver module, the route response message sending for receiving this user data server, wherein, this route response message is carried the switching routing number of this user ID association, and this switching routing number is obtained according to this user ID by this user data server;

This sending module also for according to this switching routing number by the circuit switching (CS) call routing of this UE to accessing switching control function entity A TCF, the media that the CS of this UE is called out anchor to the access that this ATCF controls and switch on gateway A TGW.

In conjunction with the possible implementation of the first of fourth aspect, in the possible implementation of the second, this user data server is for merging HLR, and this switching routing number is preserved in the IMS of this UE register flow path by this fusion HLR.

In conjunction with the possible implementation of the first of fourth aspect, in the third possible implementation, this user data server is HLR, and this switching routing number is received and preserves from home subscriber server HSS in the IMS of this UE register flow path by this HLR.

In conjunction with any the possible implementation in first to three kind of possible implementation of fourth aspect or fourth aspect, in the 4th kind of possible implementation, this receiver module is also for before sending route request information at this sending module to user data server, receive the CS call setup message that this UE sends, this CS call setup message carries session Handover Number STN;

This sending module is specifically for sending this route request information to this user data server, this route request information is carried this STN and this user ID, so that this user data server determines that according to this STN the CS of this UE calls out as the calling for switching and obtains this switching routing number according to this user ID.

In conjunction with any the possible implementation in first to fourth kind of fourth aspect or fourth aspect possible implementation, in the 5th kind of possible implementation, this switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.

Based on technique scheme, the embodiment of the present invention by route response message to switching center equipment return switch routing number so that switching center equipment by the CS call routing of UE to ATCF, the media that the CS of UE can be called out anchor on the ATGW of ATCF control, can save the renewal in distant end media path, thereby can shorten handover delay, improve user and experience.

Brief description of the drawings

In order to be illustrated more clearly in the technical scheme of the embodiment of the present invention, to the accompanying drawing of required use in the embodiment of the present invention be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.

Fig. 1 is the indicative flowchart that keeps according to an embodiment of the invention the method for call continuity.

Fig. 2 closes according to the HLR of the embodiment of the present invention and HSS the conveying flow figure that switches routing number in the scene of establishing.

Fig. 3 is the conveying flow figure that switches routing number in the scene setting up separately according to the HLR of the embodiment of the present invention and HSS.

Fig. 4 is the calling switching flow figure according to the UE of the embodiment of the present invention.

Fig. 5 is the indicative flowchart that keeps according to another embodiment of the present invention the method for call continuity.

Fig. 6 is the schematic block diagram of user data server according to an embodiment of the invention.

Fig. 7 is the schematic block diagram of switching center equipment according to an embodiment of the invention.

Fig. 8 is the schematic diagram of user data server according to another embodiment of the present invention.

Fig. 9 is the schematic diagram of switching center equipment according to another embodiment of the present invention.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is a part of embodiment of the present invention, instead of whole embodiment.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under the prerequisite of not making creative work, should belong to the scope of protection of the invention.

The technical scheme of the embodiment of the present invention can be applied in the system that need to switch from packet switching (Packet Switching, PS) to CS.For example, CS network covers comprehensively, the system that LTE network portion covers, wherein, CS network can be global system for mobile telecommunications (Global System of Mobile communication, GSM), the core net circuit domain switching network of the system such as code division multiple access (Code Division Multiple Access, CDMA), Wideband Code Division Multiple Access (WCDMA) (Wideband Code Division Multiple Access, WCDMA).

Should understand, in embodiments of the present invention, switching center equipment can be (the Mobile Services Switching Centre of mobile switching centre, MSC), mobile soft switch (MSC Server) or CDMA move soft switch (Mobile Switching Center emulation, MSCe), the embodiment of the present invention does not limit this, but for convenience of description, following embodiment will describe as an example of MSC example.

Will also be understood that, in embodiments of the present invention, user data server can be anastomosing home location register (Home Location Register, HLR), also can be expressed as anastomosing home client server (Home Subscriber Server, HSS), namely HLR and HSS close the equipment of establishing; User data server can be also the HLR setting up separately with HSS.

Will also be understood that, in embodiments of the present invention, subscriber equipment (User Equipment, UE) can be referred to as terminal (Terminal), travelling carriage (Mobile Station, MS), mobile terminal (Mobile Terminal) etc., this subscriber equipment can be through wireless access network (Radio Access Network, RAN) communicate with one or more core net, for example, subscriber equipment can be mobile phone (or being called " honeycomb " phone), there is the computer of mobile terminal etc., for example, subscriber equipment can also be portable, pocket, hand-hold type, built-in computer or vehicle-mounted mobile device, they and wireless access network switched voice and/or data.

Fig. 1 shows according to the indicative flowchart of the method 100 of the maintenance call continuity of the embodiment of the present invention.The method of Fig. 1 can be carried out by user data server.As shown in Figure 1, the method 100 comprises:

S110, receives the route request information that switching center equipment sends, and wherein, this route request information is carried the user ID of UE;

S120, obtains the switching routing number of this user ID association according to this user ID;

S130, sends route response message to switching center equipment, and this route response message is carried this switching routing number, this switching routing number for make switching center equipment by the CS call routing of UE to ATCF.

In embodiments of the present invention, in the time that the UE of access PS network need to access switching, switching center equipment (being described as an example of MSC example below) sends route request information to user data server (merging HLR or HLR), for example SRI (Sending Routing Information), this route request information is carried the user ID of UE.User ID represents calling number, for example, user ID can be C-MSISDN, Mobile Subscriber International ISDN number (Mobile Station International ISDN Number, or Mobile Directory Number (Mobile Directory Number, MDN) MSISDN).User ID can be obtained from signing user data.

User data server receives after the route request information of MSC, obtains the switching routing number of this user ID association, and this switching routing number is carried in route response message and sends to MSC.This switching routing number is access switching control function entity (Access Transfer Control Function, ATCF) number that the calling for UE distributing in the IMS of UE register flow path is switched, can be by the call routing of UE to this ATCF according to this switching routing number.For example, this switching routing number can be for single wireless voice calling continuity (Single Radio Voice Call Continuity, SRVCC) session Handover Number (Session Transfer Number for SRVCC, STN-SR), or for the session Handover Number of DRVCC, be called in embodiments of the present invention Session Transfer Number for DRVCC (STN-DR).

MSC find the address of this ATCF according to this switching routing number so that by the CS call routing of UE to ATCF.For example, send calling invitation message to this ATCF, or, calling invitation message sent by other network elements to this ATCF.This calling invitation message is carried this switching routing number, ATCF calls out with the original PS of UE and calls out according to the CS of the associated UE of this switching routing number, and control and access switching gateway (Access Transfer Gateway, ATGW) set up the media path of the CS calling of UE, thereby the media of the CS calling of UE are anchored on this ATGW.ATGW does not need to upgrade to the media path of far-end UE, like this, after the media that the CS of UE is called out anchor on ATGW, has completed the switching of UE from PS to CS, has shortened handover delay, experiences thereby can improve user.

Therefore, the method of the maintenance call continuity of the embodiment of the present invention, by in route response message to switching center equipment return switch routing number so that switching center equipment by the CS call routing of UE to ATCF, the media that the CS of UE can be called out anchor on the ATGW of ATCF control, can save the renewal in distant end media path, thereby can shorten handover delay, improve user and experience.

In embodiments of the present invention, switching routing number is the number that the calling for UE that distributes in the IMS of UE register flow path of ATCF is switched.That is to say, this switching routing number is distributed by ATCF in the IMS of UE register flow path.Alternatively, switching routing number can be STN-SR.Should be understood that switching routing number also can not adopt STN-SR, and adopt other numbers, for example above-mentioned STN-DR.That is to say, ATCF can distribute a number different from STN-SR to switch for the calling of follow-up UE in the IMS of UE register flow path.

In the IMS of UE register flow path, ATCF distributes after switching routing number, transmits this switching routing number in registration message.

Close the scene of establishing for HLR and HSS, be that user data server is while merging HLR, the bang path that switches routing number is ATCF->CSCF->SCC AS->HLR/HSS, and wherein, HLR/HSS represents to merge HLR.Therefore, in embodiments of the present invention, alternatively, before S110, the method 100 also comprises:

Merge HLR and in the IMS of UE register flow path, receive the switching routing number that SCC AS sends and preserve and switch routing number, wherein, switch routing number and distributed in the IMS of UE register flow path by ATCF and pass to SCC AS.

In this case, obtain the switching routing number of this user ID association according to this user ID, be specifically as follows:

Merging HLR obtains and merges the switching routing number that HLR preserves in the IMS of UE register flow path according to this user ID.

That is to say, for merging HLR, SCC AS sends to merging HLR the switching routing number that ATCF distributes, and merges HLR this switching routing number is preserved, and it is associated with the user ID of UE, in the time that follow-up MSC gets route, this switching routing number is returned to MSC.

The scene setting up separately for HLR and HSS, the bang path that switches routing number is ATCF->CSCF->SCC AS->HSS->HLR.Therefore, in embodiments of the present invention, alternatively, before S110, the method 100 also comprises:

HLR receives the switching routing number that HSS sends and preserves and switches routing number in the IMS of UE register flow path, wherein, switches routing number and is distributed in the IMS of UE register flow path by ATCF and pass to HSS.

HLR obtains according to this user ID the switching routing number that HLR preserves in the IMS of UE register flow path.

That is to say, in the time that HLR and HSS set up separately, the switching routing number that HSS distributes ATCF sends to HLR.HLR preserves this switching routing number, and it is associated with the user ID of signing UE.In the time that follow-up MSC gets route, HLR obtains and switches routing number and this switching routing number is returned to MSC according to the user ID of UE.

In embodiments of the present invention, alternatively, the route request information that switching center equipment sends can also be carried STN.

In this case, before S120, the method 100 also comprises:

Particularly, in the time that the UE of access PS network need to access switching, for example, when UE moves to the border of LTE covering, UE initiates CS by CS network and calls out.UE sends CS call setup message to MSC, carries STN.STN represents that the CS that needs are set up calls out as the calling for switching, and is switched to the calling of CS from PS.MSC, receiving after the CS call setup message of UE transmission, sends route request information to user data server, for example SRI, and this route request information is carried the user ID of this STN and UE.User data server receives after the route request information of MSC, determine that according to this STN the CS of UE calls out as the calling for switching, therefore, user data server obtains the switching routing number of this user ID association, and this switching routing number is carried in route response message and sends to MSC.

The conveying flow of the switching routing number below in conjunction with Fig. 2 to Fig. 4 to the embodiment of the present invention and the calling switching flow of UE are described.It should be noted that this is just in order to help those skilled in the art to understand better the embodiment of the present invention, and the scope of the unrestricted embodiment of the present invention.

Fig. 2 is that HLR and HSS close the conveying flow figure that switches routing number in the scene of establishing.HLR/HSS in Fig. 2 represents to merge HLR.For outstanding committed step of the present invention, part entity and flow process are omitted.

201, UE initiates IMS register flow path.

202, UE sends registration message to ATCF.

203, ATCF distributes switching routing number.

ATCF distributes switching routing number, switches for the calling of follow-up UE.Session that can grappling UE according to this switching routing number is to ATGW.For example, this switching routing number can be STN-SR or STN-DR.

204, ATCF sends registration message to S-CSCF, carries switching routing number, and switching routing number is passed to S-CSCF.

205, S-CSCF sends registration message to SCC AS, carries switching routing number, and switching routing number is passed to SCC AS.

206, SCC AS sends data synchronization message to HLR/HSS, carries switching routing number, and switching routing number is passed to HLR/HSS.

207, HLR/HSS sends data sync response to SCC AS.

Switch routing number by transmitting in the IMS of UE register flow path, HLR/HSS can obtain the switching routing number that ATCF distributes, and in the time that follow-up MSC gets route, this switching routing number is returned to MSC.In embodiments of the present invention, in HLR, in signing MSISDN and HSS, signing C-MSISDN is identical, and like this, HLR/HSS can be according to the user ID of UE, i.e. identical MSISDN switching associated with C-MSISDN routing number and user ID.

Fig. 3 is the conveying flow figure that switches routing number in the scene that sets up separately of HLR and HSS.For outstanding committed step of the present invention, part entity and flow process are omitted.

301, UE initiates IMS register flow path.

302, UE sends registration message to ATCF.

303, ATCF distributes switching routing number.

ATCF distributes switching routing number, switches for the calling of follow-up UE.Session that can grappling UE according to this switching routing number.For example, this switching routing number can be STN-SR or STN-DR.

304, ATCF sends registration message to S-CSCF, carries switching routing number, and switching routing number is passed to S-CSCF.

305, S-CSCF sends registration message to SCC AS, carries switching routing number, and switching routing number is passed to SCC AS.

306, SCC AS sends data synchronization message to HSS, carries switching routing number, and switching routing number is passed to HSS.

307, HSS sends data sync response to SCC AS.

308, HSS sends data synchronization message to HLR, carries switching routing number.

309, HLR sends data sync response to HSS.

In embodiments of the present invention, in HLR, in signing MSISDN and HSS, signing C-MSISDN is identical, and like this, HLR can be according to the user ID of UE, i.e. the MSISDN identical with C-MSISDN associated switching routing number and user ID.Switch routing number by transmitting in the IMS of UE register flow path, finally by HSS, switching routing number is sent to HLR, HLR can obtain the switching routing number that ATCF distributes, in the time that follow-up MSC gets route, HLR obtains and switches routing number and this switching routing number is returned to MSC according to the user ID of UE.

Fig. 4 is the calling switching flow figure of the UE of the embodiment of the present invention.Fig. 4 describes as an example of fusion HLR (HLR/HSS) example.Should be understood that for the HLR setting up separately, corresponding flow process is similar to Fig. 4.In Fig. 4, to switch routing number and adopt STN-SR, the user ID of UE adopts C-MSISDN, should be understood that for other and switches routing number and user ID, and the flow process of Fig. 4 is suitable for too.For outstanding committed step of the present invention, part entity and flow process are omitted.In Fig. 4, UE1 initiates the UE that CS calls out, and UE2 is far-end UE.

401, UE1 sends CS call setup message to MSC.

UE1 determines need to access switching time, initiates CS call out by CS network, sends CS call setup message to MSC, carries STN.

402, MSC sends SRI to HLR/HSS, carries the C-MSISDN of this STN and UE.

403, HLR/HSS sends SRI ACK to MSC, carries STN-SR.

HLR/HSS determines that according to STN the CS of UE calls out as the calling for switching, and therefore, the STN-SR preserving in the IMS of UE register flow path that obtains C-MSISDN association returns to MSC.

404, MSC sends calling invitation message (INVITE) to ATCF, carries the C-MSISDN of STN-SR and UE.

MSC finds ATCF according to STN-SR, and calling invitation message is sent to ATCF, that is to say CS call routing to ATCF.

405, ATCF sends configuration messages to ATGW.

ATCF calls out with the original PS of UE and calls out according to the CS of the associated UE of STN-SR, and set up the media path of the CS calling of UE to ATGW transmission configuration messages control ATGW, set up the media path of CS-MGW to ATGW, thereby the media that the CS of UE is called out anchor on this ATGW.

406, ATGW sends configure-ack message to ATCF.

407, ATCF sends response message to MSC.

Till this step completes CS call establishment.

408, ATCF sends access to SCC AS and switches updating message.

409, SCC AS sends response message to ATCF.

SCC AS completes session updates, sends response to ATCF.

410, SCC AS discharges LTE access leg.

411, ATCF discharges LTE access leg.

In embodiments of the present invention, according to STN-SR, calling is sent to ATCF, saved the process of intelligent grappling, simplified call chain, no longer pass through the network elements such as MGCF (Media Gateway Control Function, MGCF) and ICSCF.In the prior art, MSC need to be by the mode of intelligent grappling, obtains IMS routing number (IMS Routing Number, IMRN), then routes the call to IMS territory according to IMRN.The grappling process of the embodiment of the present invention is simplified by comparison greatly.Because the embodiment of the present invention has been saved the process that the new media of CS access leg is sent to far-end UE, therefore save the time that media upgrade, shorten handoff duration.

In addition, the technical scheme of the embodiment of the present invention changes smaller to the existing network architecture, and network design complexity is low, convenient deployment and enforcement.

The method of the maintenance call continuity of the embodiment of the present invention, by return to MSC the switching routing number that ATCF distributes in route response message, MSC by the CS call routing of UE to ATCF, the media that the CS of UE can be called out anchor on the ATGW of ATCF control, can save the renewal in distant end media path, thereby can shorten handover delay, improve user and experience.

Describe in detail according to the method for the maintenance call continuity of the embodiment of the present invention from the angle of user data server above, the angle from switching center equipment is described to the method that keeps according to another embodiment of the present invention call continuity below.

Fig. 5 shows the indicative flowchart of the method 500 that keeps according to another embodiment of the present invention call continuity.The method of Fig. 5 can be carried out by switching center equipment.As shown in Figure 5, the method 500 comprises:

S510, sends route request information to user data server, and this route request information is carried the user ID of UE;

S520, receives the route response message that this user data server sends, and wherein, this route response message is carried the switching routing number of this user ID association, and this switching routing number is obtained according to this user ID by this user data server;

S530, according to this switching routing number by the CS call routing of UE to ATCF, the media that the CS of UE is called out anchor on the ATGW that this ATCF controls.

The method of the maintenance call continuity of the embodiment of the present invention, by receive the switching routing number that sends of user data server in route response message and according to this switching routing number by the CS call routing of UE to ATCF, the media that the CS of UE can be called out anchor on the ATGW of ATCF control, can save the renewal in distant end media path, thereby can shorten handover delay, improve user and experience.

In embodiments of the present invention, switching routing number is the number that the calling for UE that distributes in the IMS of UE register flow path of ATCF is switched.That is to say, this switching routing number is distributed by ATCF in the IMS of UE register flow path.Alternatively, switching routing number can be STN-SR.Should be understood that switching routing number also can not adopt STN-SR, and adopt other numbers, for example STN-DR.That is to say, ATCF can distribute a number different from STN-SR to switch for the calling of follow-up UE in the IMS of UE register flow path.

In embodiments of the present invention, the user ID of UE can be C-MSISDN, MSISDN or MDN.

Close the scene of establishing for HLR and HSS, be that user data server is while merging HLR, the bang path that switches routing number is ATCF->CSCF->SCC-AS-GreatT.Gr eaT.GTHLR/HSS, and wherein, HLR/HSS represents to merge HLR.Therefore, in embodiments of the present invention, alternatively, user data server is while merging HLR, switches routing number and preserves in the IMS of UE register flow path by merging HLR.

The scene setting up separately for HLR and HSS, the bang path that switches routing number is ATCF->CSCF->SCC-AS-GreatT.Gr eaT.GTHSS->HLR.Therefore, in embodiments of the present invention, alternatively, when user data server is HLR, switches routing number and receive and preserve from HSS in the IMS of UE register flow path by HLR.

Alternatively, before S510, the method 500 also comprises:

Receive the CS call setup message that this UE sends, this CS call setup message carries STN.

In this case, send route request information to user data server, comprising:

Send route request information to user data server, this route request information is carried this STN and this user ID, so that this user data server determines that according to this STN the CS of this UE calls out as the calling for switching and obtains this switching routing number according to this user ID.

Should be understood that in embodiments of the present invention, each equipment that user data server side is described mutual and correlation properties, function etc. is each other corresponding with the description of switching center equipment side, for simplicity, does not repeat them here.

Will also be understood that, in various embodiment of the present invention, the size of the sequence number of above-mentioned each process does not also mean that the priority of execution sequence, and the execution sequence of each process should determine with its function and internal logic, and should not form any restriction to the implementation process of the embodiment of the present invention.

Above, in conjunction with Fig. 1 to Fig. 5, describe in detail according to the method for the maintenance call continuity of the embodiment of the present invention, below in conjunction with Fig. 6 to Fig. 9, describe according to the user data server of the embodiment of the present invention and switching center equipment.

Fig. 6 shows according to the schematic block diagram of the user data server 600 of the embodiment of the present invention.As shown in Figure 6, this user data server 600 comprises:

Receiver module 610, the route request information sending for receiving switching center equipment, wherein, this route request information is carried the user ID of user equipment (UE);

Acquisition module 620, for obtaining the switching routing number of this user ID association according to this user ID;

Sending module 630, for sending route response message to this switching center equipment, this route response message is carried this switching routing number, this switching routing number for make this switching center equipment by the CS call routing of this UE to accessing switching control function entity A TCF.

The user data server of the embodiment of the present invention, by in route response message to switching center equipment return switch routing number so that switching center equipment by the CS call routing of UE to ATCF, the media that the CS of UE can be called out anchor on the ATGW of ATCF control, can save the renewal in distant end media path, thereby can shorten handover delay, improve user and experience.

In embodiments of the present invention, alternatively, this switching routing number is the number that the calling for this UE that distributes in the internet protocol multi-media sub-system IMS of this UE register flow path of this ATCF is switched.

In embodiments of the present invention, alternatively, this user data server 600 is for merging HLR.

This receiver module 610 also receives for the IMS register flow path at this UE this switching routing number that business coherence and continuity application server SCC AS sends, wherein, this switching routing number is distributed in the IMS of this UE register flow path by this ATCF and passes to this SCC AS.

This user data server 600 also comprises:

The first memory module, for preserving this switching routing number.

This acquisition module 620 this switching routing number specifically for preserving in the IMS register flow path obtaining at this UE according to this user ID.

In embodiments of the present invention, alternatively, this user data server 600 is HLR.

This receiver module 610 also receives for the IMS register flow path at this UE this switching routing number that home subscriber server HSS sends, and wherein, this switching routing number is distributed in the IMS of this UE register flow path by this ATCF and passes to this HSS.

This user data server 600 also comprises:

The second memory module, for preserving this switching routing number.

In embodiments of the present invention, alternatively, this route request information that this receiver module 610 receives is also carried session Handover Number STN.

This user data server 600 also comprises:

Determination module, this STN carrying for this route request information receiving according to this receiver module 610 determines that the CS of this UE calls out as the calling for switching.

In embodiments of the present invention, alternatively, this switching routing number is STN-SR or STN-DR.

Can be corresponding to according to the user data server in the method for the maintenance call continuity of the embodiment of the present invention according to the user data server 600 of the embodiment of the present invention, and above-mentioned and other operation of the modules in user data server 600 and/or function are respectively in order to realize the corresponding flow process of each method in Fig. 1 to Fig. 5, for simplicity, do not repeat them here.

Fig. 7 shows according to the schematic block diagram of the switching center equipment 700 of the embodiment of the present invention.As shown in Figure 7, this switching center equipment 700 comprises:

Sending module 710, for sending route request information to user data server, this route request information is carried the user ID of user equipment (UE);

Receiver module 720, the route response message sending for receiving this user data server, wherein, this route response message is carried the switching routing number of this user ID association, and this switching routing number is obtained according to this user ID by this user data server;

This sending module 710 also for according to this switching routing number by the CS call routing of this UE to accessing switching control function entity A TCF, the media that the CS of this UE is called out anchor to the access that this ATCF controls and switch on gateway A TGW.

The switching center equipment of the embodiment of the present invention, by receive the switching routing number that sends of user data server in route response message and according to this switching routing number by the CS call routing of UE to ATCF, the media that the CS of UE can be called out anchor on the ATGW of ATCF control, can save the renewal in distant end media path, thereby can shorten handover delay, improve user and experience.

In embodiments of the present invention, alternatively, this user data server is for merging HLR, and this switching routing number is preserved in the IMS of this UE register flow path by this fusion HLR.

In embodiments of the present invention, alternatively, this user data server is HLR, and this switching routing number is received and preserves from home subscriber server HSS in the IMS of this UE register flow path by this HLR.

In embodiments of the present invention, alternatively, this receiver module 720 also, for before sending route request information at this sending module 710 to user data server, receives the CS call setup message that this UE sends, and this CS call setup message carries session Handover Number STN;

This sending module 710 is specifically for sending this route request information to this user data server, this route request information is carried this STN and this user ID, so that this user data server determines that according to this STN the CS of this UE calls out as the calling for switching and obtains this switching routing number according to this user ID.

Can be corresponding to according to the switching center equipment in the method for the maintenance call continuity of the embodiment of the present invention according to the switching center equipment 700 of the embodiment of the present invention, and above-mentioned and other operation of the modules in switching center equipment 700 and/or function are respectively in order to realize the corresponding flow process of each method in Fig. 1 to Fig. 5, for simplicity, do not repeat them here.

Fig. 8 shows the structure of the user data server that another embodiment of the present invention provides, comprise at least one processor 802 (for example CPU), at least one network interface 805 or other communication interfaces, memory 806, with at least one communication bus 803, for realizing the connection communication between these devices.Processor 802 for example, for the executable module of execute store 806 storages, computer program.Memory 806 may comprise high-speed random access memory (RAM:Random Access Memory), also may also comprise non-unsettled memory (non-volatile memory), for example at least one magnetic disc store.Realize the communication connection between at least one other network element by least one network interface 805 (can be wired or wireless).

In some embodiments, memory 806 has been stored program 8061, processor 802 executive programs 8061, for carrying out following operation:

Receive by network interface the route request information that switching center equipment sends, wherein, this route request information is carried the user ID of user equipment (UE);

Send route response message by network interface to this switching center equipment, this route response message is carried this switching routing number, this switching routing number for make this switching center equipment by the CS call routing of this UE to accessing switching control function entity A TCF.

Alternatively, this switching routing number is the number that the calling for this UE that distributes in the internet protocol multi-media sub-system IMS of this UE register flow path of this ATCF is switched.

Alternatively, this user data server is for merging HLR; This processor is also for being received this switching routing number of business coherence and continuity application server SCC AS transmission and preserve this switching routing number at the IMS of this UE register flow path by network interface, wherein, this switching routing number is distributed in the IMS of this UE register flow path by this ATCF and passes to this SCC AS;

This processor this switching routing number specifically for preserving in the IMS register flow path obtaining at this UE according to this user ID.

Alternatively, this user data server is HLR; This processor is also for being received this switching routing number of home subscriber server HSS transmission and preserve this switching routing number at the IMS of this UE register flow path by network interface, wherein, this switching routing number is distributed in the IMS of this UE register flow path by this ATCF and passes to this HSS;

Alternatively, this route request information is also carried session Handover Number STN;

This processor is also for determining that according to this STN the CS of this UE calls out as the calling for switching.

Alternatively, this switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.

The above technical scheme providing from the embodiment of the present invention can be found out, the embodiment of the present invention by route response message to switching center equipment return switch routing number so that switching center equipment by the CS call routing of UE to ATCF, the media that the CS of UE can be called out anchor on the ATGW of ATCF control, can save the renewal in distant end media path, thereby can shorten handover delay, improve user and experience.

Fig. 9 shows the structure of the switching center equipment that another embodiment of the present invention provides, comprise at least one processor 902 (for example CPU), at least one network interface 905 or other communication interfaces, memory 906, with at least one communication bus 903, for realizing the connection communication between these devices.Processor 902 for example, for the executable module of execute store 906 storages, computer program.Memory 906 may comprise high-speed random access memory (RAM:Random Access Memory), also may also comprise non-unsettled memory (non-volatile memory), for example at least one magnetic disc store.Realize the communication connection between at least one other network element by least one network interface 905 (can be wired or wireless).

In some embodiments, memory 906 has been stored program 9061, processor 902 executive programs 9061, for carrying out following operation:

Send route request information by network interface to user data server, this route request information is carried the user ID of user equipment (UE);

Receive by network interface the route response message that this user data server sends, wherein, this route response message is carried the switching routing number of this user ID association, and this switching routing number is obtained according to this user ID by this user data server;

According to this switching routing number by network interface by the CS call routing of this UE to accessing switching control function entity A TCF, the media that the CS of this UE is called out anchor to the access that this ATCF controls and switch on gateway A TGW.

Alternatively, this user data server is for merging HLR, and this switching routing number is preserved in the IMS of this UE register flow path by this fusion HLR.

Alternatively, this user data server is HLR, and this switching routing number is received and preserves from home subscriber server HSS in the IMS of this UE register flow path by this HLR.

Alternatively, this processor also, for sending before route request information to user data server by network interface, receives the CS call setup message that this UE sends, and this CS call setup message carries session Handover Number STN;

This processor is specifically for sending this route request information by network interface to this user data server, this route request information is carried this STN and this user ID, so that this user data server determines that according to this STN the CS of this UE calls out as the calling for switching and obtains this switching routing number according to this user ID.

The above technical scheme providing from the embodiment of the present invention can be found out, the embodiment of the present invention by receive the switching routing number that sends of user data server in route response message and according to this switching routing number by the CS call routing of UE to ATCF, the media that the CS of UE can be called out anchor on the ATGW of ATCF control, can save the renewal in distant end media path, thereby can shorten handover delay, improve user and experience.

Should be understood that in embodiments of the present invention, term "and/or" is only a kind of incidence relation of describing affiliated partner, and expression can exist three kinds of relations.For example, A and/or B, can represent: individualism A exists A and B, these three kinds of situations of individualism B simultaneously.In addition, character "/" herein, generally represents that forward-backward correlation is to liking a kind of relation of "or".

Those of ordinary skill in the art can recognize, unit and the algorithm steps of each example of describing in conjunction with embodiment disclosed herein, can realize with electronic hardware, computer software or the combination of the two, for the interchangeability of hardware and software is clearly described, composition and the step of each example described according to function in the above description in general manner.These functions are carried out with hardware or software mode actually, depend on application-specific and the design constraint of technical scheme.Professional and technical personnel can realize described function with distinct methods to each specifically should being used for, but this realization should not thought and exceeds scope of the present invention.

Those skilled in the art can be well understood to, and for convenience of description and succinctly, the specific works process of the system of foregoing description, device and unit, can, with reference to the corresponding process in preceding method embodiment, not repeat them here.

In the several embodiment that provide in the application, should be understood that disclosed system, apparatus and method can realize by another way.For example, device embodiment described above is only schematic, for example, the division of described unit, be only that a kind of logic function is divided, when actual realization, can have other dividing mode, for example multiple unit or assembly can in conjunction with or can be integrated into another system, or some features can ignore, or do not carry out.In addition, shown or discussed coupling each other or direct-coupling or communication connection can be indirect coupling or communication connections by some interfaces, device or unit, can be also electric, machinery or other form connect.

The described unit as separating component explanation can or can not be also physically to separate, and the parts that show as unit can be or can not be also physical locations, can be positioned at a place, or also can be distributed in multiple network element.Can select according to the actual needs some or all of unit wherein to realize the object of embodiment of the present invention scheme.

In addition, the each functional unit in each embodiment of the present invention can be integrated in a processing unit, can be also that the independent physics of unit exists, and can be also that two or more unit are integrated in a unit.Above-mentioned integrated unit both can adopt the form of hardware to realize, and also can adopt the form of SFU software functional unit to realize.

If described integrated unit is realized and during as production marketing independently or use, can be stored in a computer read/write memory medium using the form of SFU software functional unit.Based on such understanding, the part that technical scheme of the present invention contributes to prior art in essence in other words, or all or part of of this technical scheme can embody with the form of software product, this computer software product is stored in a storage medium, comprise that some instructions (can be personal computers in order to make a computer equipment, server, or the network equipment etc.) carry out all or part of step of method described in each embodiment of the present invention.And aforesaid storage medium comprises: USB flash disk, portable hard drive, read-only memory (ROM, Read-Only Memory), the various media that can be program code stored such as random access memory (RAM, Random Access Memory), magnetic disc or CD.

The above; it is only the specific embodiment of the present invention; but protection scope of the present invention is not limited to this; any be familiar with those skilled in the art the present invention disclose technical scope in; can expect easily amendment or the replacement of various equivalences, within these amendments or replacement all should be encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.

Claims

1. a method that keeps call continuity, is characterized in that, comprising:

Receive the route request information that switching center equipment sends, wherein, described route request information is carried the user ID of user equipment (UE);

Obtain the switching routing number of described user ID association according to described user ID;

Send route response message to described switching center equipment, described route response message is carried described switching routing number, described switching routing number for make described switching center equipment by the circuit switching (CS) call routing of described UE to accessing switching control function entity A TCF.

2. method according to claim 1, is characterized in that, described switching routing number is the number that the calling for described UE that distributes in the internet protocol multi-media sub-system IMS of described UE register flow path of described ATCF is switched.

3. method according to claim 2, is characterized in that, before the route request information sending in described reception switching center equipment, described method also comprises:

Anastomosing home location register HLR receives the described switching routing number of business coherence and continuity application server SCC AS transmission and preserves described switching routing number in the IMS of described UE register flow path, wherein, described switching routing number is distributed in the IMS of described UE register flow path by described ATCF and passes to described SCC AS;

The described switching routing number that obtains described user ID association according to described user ID, comprising:

Described fusion HLR obtains according to described user ID the described switching routing number that described fusion HLR preserves in the IMS of described UE register flow path.

4. method according to claim 2, is characterized in that, before the route request information sending in described reception switching center equipment, described method also comprises:

HLR receives the described switching routing number of home subscriber server HSS transmission and preserves described switching routing number in the IMS of described UE register flow path, wherein, described switching routing number is distributed in the IMS of described UE register flow path by described ATCF and passes to described HSS;

Described HLR obtains according to described user ID the described switching routing number that described HLR preserves in the IMS of described UE register flow path.

5. according to the method described in any one in claim 1 to 4, it is characterized in that, described route request information is also carried session Handover Number STN;

Before the described switching routing number that obtains described user ID association according to described user ID, described method also comprises:

Determine that according to described STN the CS of described UE calls out as the calling for switching.

6. according to the method described in any one in claim 1 to 5, it is characterized in that, described switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.

7. a method that keeps call continuity, is characterized in that, comprising:

Send route request information to user data server, described route request information is carried the user ID of user equipment (UE);

Receive the route response message that described user data server sends, wherein, described route response message is carried the switching routing number of described user ID association, and described switching routing number is obtained according to described user ID by described user data server;

According to described switching routing number by the circuit switching (CS) call routing of described UE to accessing switching control function entity A TCF, the media that the CS of described UE is called out anchor to the access that described ATCF controls and switch on gateway A TGW.

8. method according to claim 7, is characterized in that, described switching routing number is the number that the calling for described UE that distributes in the internet protocol multi-media sub-system IMS of described UE register flow path of described ATCF is switched.

9. method according to claim 8, is characterized in that, described user data server is anastomosing home location register HLR, and described switching routing number is preserved in the IMS of described UE register flow path by described fusion HLR.

10. method according to claim 8, is characterized in that, described user data server is HLR, and described switching routing number is received and preserves from home subscriber server HSS in the IMS of described UE register flow path by described HLR.

11. according to the method described in any one in claim 7 to 10, it is characterized in that, described, before user data server transmission route request information, described method also comprises:

Receive the CS call setup message that described UE sends, described CS call setup message carries session Handover Number STN;

Described to user data server transmission route request information, comprising:

Send described route request information to described user data server, described route request information is carried described STN and described user ID, so that described user data server determines that according to described STN the CS of described UE calls out as the calling for switching and obtains described switching routing number according to described user ID.

12. according to the method described in any one in claim 7 to 11, it is characterized in that, described switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.

13. 1 kinds of user data servers, is characterized in that, comprising:

Receiver module, the route request information sending for receiving switching center equipment, wherein, described route request information is carried the user ID of user equipment (UE);

Acquisition module, for obtaining the switching routing number of described user ID association according to described user ID;

Sending module, for sending route response message to described switching center equipment, described route response message is carried described switching routing number, described switching routing number for make described switching center equipment by the circuit switching (CS) call routing of described UE to accessing switching control function entity A TCF.

14. user data servers according to claim 13, is characterized in that, described switching routing number is the number that the calling for described UE that distributes in the internet protocol multi-media sub-system IMS of described UE register flow path of described ATCF is switched.

15. user data servers according to claim 14, is characterized in that, described user data server is anastomosing home location register HLR;

Described receiver module also receives for the IMS register flow path at described UE the described switching routing number that business coherence and continuity application server SCC AS sends, wherein, described switching routing number is distributed in the IMS of described UE register flow path by described ATCF and passes to described SCC AS;

Described user data server also comprises:

The first memory module, for preserving described switching routing number;

The described switching routing number of described acquisition module specifically for preserving in the IMS register flow path obtaining at described UE according to described user ID.

16. user data servers according to claim 14, is characterized in that, described user data server is HLR;

Described receiver module also receives for the IMS register flow path at described UE the described switching routing number that home subscriber server HSS sends, wherein, described switching routing number is distributed in the IMS of described UE register flow path by described ATCF and passes to described HSS;

Described user data server also comprises:

The second memory module, for preserving described switching routing number;

17. according to claim 13 to the user data server described in any one in 16, it is characterized in that, the described route request information that described receiver module receives is also carried session Handover Number STN;

Described user data server also comprises:

Determination module, the described STN carrying for the described route request information receiving according to described receiver module determines that the CS of described UE calls out as the calling for switching.

18. according to claim 13 to the user data server described in any one in 17, it is characterized in that, described switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.

19. 1 kinds of switching center equipment, is characterized in that, comprising:

Sending module, for sending route request information to user data server, described route request information is carried the user ID of user equipment (UE);

Receiver module, the route response message sending for receiving described user data server, wherein, described route response message is carried the switching routing number of described user ID association, and described switching routing number is obtained according to described user ID by described user data server;

Described sending module also for according to described switching routing number by the circuit switching (CS) call routing of described UE to accessing switching control function entity A TCF, the media that the CS of described UE is called out anchor to the access that described ATCF controls and switch on gateway A TGW.

20. switching center equipment according to claim 19, is characterized in that, described switching routing number is the number that the calling for described UE that distributes in the internet protocol multi-media sub-system IMS of described UE register flow path of described ATCF is switched.

21. switching center equipment according to claim 20, is characterized in that, described user data server is anastomosing home location register HLR, and described switching routing number is preserved in the IMS of described UE register flow path by described fusion HLR.

22. switching center equipment according to claim 20, is characterized in that, described user data server is HLR, and described switching routing number is received and preserves from home subscriber server HSS in the IMS of described UE register flow path by described HLR.

23. according to claim 19 to the switching center equipment described in any one in 22, it is characterized in that, described receiver module is also for before sending route request information at described sending module to user data server, receive the CS call setup message that described UE sends, described CS call setup message carries session Handover Number STN;

Described sending module is specifically for sending described route request information to described user data server, described route request information is carried described STN and described user ID, so that described user data server determines that according to described STN the CS of described UE calls out as the calling for switching and obtains described switching routing number according to described user ID.

24. according to claim 19 to the switching center equipment described in any one in 23, it is characterized in that, described switching routing number is for the session Handover Number of single wireless voice calling continuity SRVCC or for the session Handover Number of two wireless voice call continuity DRVCC.