CN101232724B

CN101232724B - Implementation method of final calling in IP multimedia subsystem

Info

Publication number: CN101232724B
Application number: CN 200810003681
Authority: CN
Inventors: 陈志峰
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2008-01-15
Filing date: 2008-01-15
Publication date: 2013-08-07
Anticipated expiration: 2028-01-15
Also published as: CN101232724A

Abstract

A method of terminating in IP Multimedia System (IMS) is provided. When a Terminal Originating a Call (TLO) initiates a conversation request to a Terminal Terminating a Call (TLT) roaming to the visiting network, an IMS network element receives a conversation request and determines whether the TLT is accessible to the local call transfer-out function in the conversation corresponding to the request and transmits the conversation request to the TLT after adding the local call transfer-out tag to the conversation request. The invention of the terminating effectively solves the problem of the media route alternation of the local terminating in the roaming service condition and modifies prior art of the IMS network slightly, which only relates to an individual network element modification, a partial process addition and a proper modification of the header field. The invention has a slight influence on prior IMS network structure and facilitates the technical update.

Description

The implementation method of exhaling eventually in a kind of IP Multimedia System

Technical field

The present invention relates to the communications field, relate in particular to the implementation method of exhaling eventually in a kind of IP (Internet Protocol, Internet protocol) IP multimedia subsystem, IMS.

Background technology

IMS (IP Multimedia Subsystem, IP Multimedia System) is third generation affiliate tissue (3 ^RdGeneration Partnership Project, abbreviation 3GPP) standard of the next generation network of definition, its distinguishing feature is to have adopted Session initiation Protocol (Session Initiation Protocol, be called for short SIP) system, communication is irrelevant with access, can possess multiple media business control function separates with bearing capacity, calling separates with session, application separates with service, business and network detach, and multiple abilities such as mobile network and internet service fusion, the trend of communication network fusion development has been complied with in the proposition of IMS.

Major function entity in the IMS system comprises: call conversation control entity (the Call Session Control Function that functions such as user's registration management, session control are provided, be called for short CSCF), home subscriber server (the Home Subscriber Server of centralized management user contracting data function is provided, be called for short HSS), the application server (Application Server is called for short AS) of miscellaneous service logic control function is provided.

Fig. 1 is the Media Stream schematic diagram that the user calls out the user terminal of this network that coexists in the prior art at its visited network.

Relate generally to following network element and equipment among Fig. 1: user terminal 1 (User Equipment 1, be called for short UE1), the gateway of visited network (Serving Gateway, be called for short SGW), user terminal 2 (User Equipment 2, be called for short UE2), the public data network gateway of home network (Public DataNetworks Gateway is called for short PGW).

As shown in Figure 1, when UE1 registered in the IMS of its ownership place network (abbreviation home network), home network was for after it has distributed an IP address, and UE1 roams into the IMS network (abbreviation visited network) on visit ground from home network; According to prior art, if when this moment, UE1 called out the user terminal UE2 of the visited network that coexists, medium need return the PGW that belongs to network from the visited network route, and then are routed to visited network by the PGW of home network, could arrive UE2.UE1 calls out UE2, and after connection, medium will be from UE1, arrive UE2 through path 101,102,103, in most of the cases 102,103 all is path distant between home network and the visited network, and route is circuitous serious, causes a large amount of waste of network resources; And for the user, because the difference of this twice routing mode charging policy also may be brought extra huge telephone expenses for the user.In like manner, when UE1 answers the phone of UE2 of this network that coexists at visited network, also there is identical detour problem.And after if medium arrive SGW, directly be routed to UE2 through path 104, will save a large amount of Internet resources, solve aforesaid network route detour problem.Will be in this case among the present invention, the mode that medium directly are routed to UE2 by path 104 is called this locality and produces.

At present 3GPP organizes also being devoted to this locality and produces important function for of research, solve the above-mentioned medium detour problem under the roaming state, and the solution of two IP address has been proposed: under the condition that ability of user terminal, carrier policy and network condition all allow, can have simultaneously respectively that operator by home network distributes IP address ip-1; And the IP address allocated IP-2 of operator of visited network, these two IP addresses can be carried out signaling plane, the communication of medium face as required respectively.

Fig. 2 is the configuration diagram of two IP addresses solution, relate generally to following network element and equipment: user terminal (User Equipment, be called for short UE), gateway (Serving Gateway, be called for short SGW), public data network gateway 2 (PDN Gateway 2, be called for short PGW-2), policy control and charging rule functions 2 (Policy Control and Charging Rules Function 2, be called for short PCRF-2), public data network gateway 1 (PDN Gateway 1, be called for short PGW-1), policy control and charging rule functions 1 (Policy Control and Charging Rules Function is called for short PCRF-1), Proxy Call Session Control Function (Proxy Call Session Control Function, be called for short P-CSCF), service call conversation control function (Serving Call Session Control Function is called for short S-CSCF), application server (Application Server is called for short AS).Wherein, UE, SGW, PGW-2, PCRF-2 are positioned at visited network; PGW-1, PCRF-1, P-CSCF, S-CSCF, AS are positioned at home network.

The main thought of two IP address solution is: use IP-1 to send signaling, use IP-2 to send medium, signaling will mail to the PGW (PGW-1) of home network by path 210 through after the SGW, and medium directly mail to the PGW (PGW-2) of visited network through after the SGW by path 211.

Because it is less relatively that signaling takies Internet resources, the circuitous of signaling can't cause the very big waste of Internet resources, and the Internet resources that medium occupy are bigger, adopt this solution to avoid the above-mentioned detour problem of medium, saved a large amount of Internet resources.

In the prior art, exhale flow process as shown in Figure 3 at the end that the IMS network is roamed under the situation normally, may further comprise the steps:

S301) be under the roaming state as called subscriber (UE among Fig. 3), the coexist calling subscriber of visited network of this moment and this called subscriber calls out this UE, and session request (INVITE) is sent on the current S-CSCF that service is provided for this UE;

S302)～S304) S-CSCF forwards this session request to P-CSCF, and P-CSCF with behind the PGW (corresponding to the PGW-1 among Fig. 2) of this session request via this UE home network, is transmitted to UE again;

S305)～S306) after UE receives above-mentioned session request, the SDP message that carries in this request is analyzed, selected the session information of the SDP message that oneself can accept, the result is included in during request (Offer) receives the response, be transmitted to P-CSCF through PGW;

S307) after P-CSCF receives that above-mentioned request is receiveed the response, according to the session information of the SDP message that wherein comprises, carry out carrying out the resource reservation authentication alternately with the resource reservation network element;

Mutual at above-mentioned resource reservation network element internal, and mutual between P-CSCF and the resource reservation network element have nothing to do with the present invention, do not elaborate here;

S308) complete successfully the resource reservation authentication after, P-CSCF is receiveed the response above-mentioned request and is forwarded to S-CSCF;

S309) S-CSCF is receiveed the response above-mentioned request and is forwarded, and finally reaches the calling subscriber;

S310～S313) calling subscriber sends request response acknowledge message to called subscriber (UE), and the forwarding of network elements such as this message approach S-CSCF, P-CSCF and PGW arrives UE;

S314～S318) UE sends request response affirmation response message to the calling subscriber;

S319) send above-mentioned request respond confirm response message after, UE carries out resource reservation, the IMS network is reserved the resource that can satisfy this session for UE;

S320)～S323) after the calling subscriber finishes resource reservation, send the resource reservation confirmation to UE, show that the calling subscriber has finished resource reservation, possesses the primary condition of session;

S324)～S327) UE finishes after the resource reservation, will send the resource reservation acknowledge message to the calling subscriber, shows that UE has finished resource reservation, possesses the primary condition of session;

S328)～S330) after UE and calling subscriber finish resource reservation, UE and calling subscriber have possessed the primary condition of setting up session, and UE finishes above capability negotiation, after the resource reservation, by the ringing user, and ALERTING message issued the calling subscriber;

S331～S334) calling subscriber receives after the ALERTING message, sends ring to UE and responds;

S335)～S338) ring of the calling subscriber's transmission of UE is replied;

S339)～S342) after UE answers, the information of answering is issued the calling subscriber;

S343)～S346) calling subscriber sends to answer and replys, and the information of answering that UE sends is replied;

S347)～S348) between UE and calling subscriber, just set up by the session that PGW transmits this moment.

Exhale flow process to find out from above-mentioned end, if UE is positioned at calling subscriber's home network, when perhaps UE and calling subscriber are positioned at same visited network simultaneously, the circuitous phenomenon of route of Media Stream shown in Figure 2 can occur, Internet resources are caused a large amount of wastes

Summary of the invention

Technical problem to be solved by this invention is, overcome the deficiencies in the prior art, the implementation method of exhaling is eventually proposed in a kind of IP Multimedia System, make called user terminal under the roaming state avoided since the route of Media Stream circuitous cause to a large amount of the taking of Internet resources.

In order to address the above problem, the invention provides the implementation method of exhaling eventually in a kind of IP Multimedia System, it is characterized in that, when calling terminal initiates a session request to the terminal called that roams into visited network, the IMS network element that receives this session request judges whether to allow this terminal called to use this locality to produce function in the session of this session request correspondence, and adds in this session request according to judged result and after mark is produced in corresponding this locality this session request to be forwarded to described terminal called.

In addition, described calling terminal is positioned at described visited network.

In addition, the IMS network element that carries out described judgement is one or more in the following network element: the P-CSCF in the described session request forward-path, the S-CSCF in the described session request forward-path, the AS that links to each other with described S-CSCF.

In addition, if AS carries out described judgement, then described S-CSCF sends to AS with this request after receiving described session request, after AS finishes described judgement, this session request is transmitted to described terminal called by described S-CSCF.

In addition, described IMS network element produces policy information according to this locality and carries out described judgement; Described this locality produce policy information comprise following one or more: operator's local policy, the agreement of signing between home network and the visited network operator, called user subscription information.

In addition, described this locality is produced mark and is comprised: allow this locality to produce, must use this locality to produce and do not allow to produce;

In the described session request that receives, comprise and allow local this locality of producing to produce mark, and when described terminal called determined to use this locality to produce function according to self terminal capability and preferred disposition, described terminal called used described visited network to carry out session parameter for its IP address allocated as the medium routing address and consults;

When comprising in the described session request that receives must use local this locality of producing to produce mark the time, described terminal called uses described visited network to carry out session parameter for its IP address allocated as the medium routing address and consults;

When comprising this locality that does not allow this locality to produce in the described session request that receives and produce mark, described terminal called uses described home network to carry out session parameter for its IP address allocated as the medium routing address and consults.

In addition, when the request that being used for of receiving that described terminal called sends, session parameter consulted is receiveed the response, if the medium routing address in this message is the IP address of described visited network, then the PCRF of P-CSCF and home network and visited network is mutual, carries out the resource reservation authentication; Otherwise the PCRF of P-CSCF and home network is mutual, carries out the resource reservation authentication.

In addition, described session request is INVITE.

In addition, described this locality is produced and is labeled as header field newly-increased in the described session request or the label in newly-increased or the existing header field.

As from the foregoing, adopt end call method of the present invention, solved local medium route detour problem of exhaling eventually under the roaming state effectively, and change little to existing IMS network technology, only relate to the modification of indivedual network elements, the interpolation of local flow process, and the suitable modification of header field, little to existing IMS network architecture influence, be convenient to carry out technology upgrading.

Description of drawings

Fig. 1 is the Media Stream schematic diagram that the user calls out the user of this visited network that coexists in the prior art at visited network;

Fig. 2 is the configuration diagram of two IP addresses solution in the prior art;

Fig. 3 be in the prior art end under the normal roaming situation exhale flow chart;

Fig. 4 is core concept schematic diagram of the present invention;

Fig. 5 is the implementation method flow chart of exhaling eventually in the first embodiment of the invention IMS network;

Fig. 6 is the implementation method flow chart of exhaling eventually in the second embodiment of the invention IMS network;

Fig. 7 is the implementation method flow chart of exhaling eventually in the third embodiment of the invention IMS network;

Fig. 8 is the implementation method flow chart of exhaling eventually in the fourth embodiment of the invention IMS network.

Embodiment

Core concept of the present invention as shown in Figure 4, after the calling subscriber who is in visited network together with the called subscriber initiated a session request to the called subscriber, IMS network and called subscriber carried out following processing:

401, after the IMS network is received session request (INVITE), judge whether the called subscriber of this session can adopt this locality to produce service;

402, after the IMS network adds sign whether the called subscriber can use this locality to produce the sign of service (mark is produced in this locality) in this session request, this session request (INVITE) is transmitted to the called subscriber;

403, the called subscriber determines whether to use this locality to produce service according to the ability of self;

404, the called subscriber uses suitable IP address to carry out the session negotiation of SDP;

405, the called subscriber uses suitable IP address by the PGW of visited network, sets up session with the calling subscriber.

Describe the present invention below in conjunction with drawings and Examples.

First embodiment

Fig. 5 is the implementation method flow chart of exhaling eventually in the first embodiment of the invention IMS network.In the present embodiment, UE roams into visited network, and the calling subscriber of this network that coexists initiates a session request to it; P-CSCF carries out this locality as decision point and produces the function decision-making, and adds this locality that allows to use this locality to produce function according to the result of decision in this session request and produce mark, and UE uses this locality to produce function according to this mark.Step is as follows among the figure:

S501) user terminal (UE) is under the roaming state, and this moment, the calling subscriber called out UE, and session request (INVITE) is sent on the current S-CSCF that service is provided for UE;

S502) S-CSCF is forwarded to this session request on the P-CSCF;

S503) P-CSCF receives after this session request, from corresponding one or more strategic server (for example, strategic server can be the PCRF:PCRF-1 of home network, P-CSCF, HSS etc., describe among the figure for to obtain information from PCRF-1, obtain information flow and to obtain information from PCRF identical from other server) obtain information, produce policy information to obtain this locality;

Above-mentioned this locality is produced policy information and can be comprised: operator's local policy, and visited network operator between agreement, user's CAMEL-Subscription-Information, the residing positional information of current calling and called both sides, network service state and the conversation media information that will initiate etc.;

S504) P-CSCF produces policy information according to above-mentioned this locality and carries out this locality and produce the function decision-making, judge whether allow called subscriber (UE) to use the local service of breathing out in this session, and in this session request (INVITE), add corresponding this locality and produce mark;

It can be header field newly-increased in the session request (for example, representing whether to allow this locality to produce respectively whether to comprise this header field) that mark is produced in above-mentioned this locality, also can be the label in newly-increased or the existing header field.

In the present embodiment, P-CSCF judges that permission UE uses this locality to produce service, and therefore corresponding this locality is produced and is labeled as: allow this locality to produce.

For example, P-CSCF can produce policy information according to this locality to carry out following this locality and produces decision-making, and adds corresponding this locality and produce mark:

1) operator's local policy: if operator's local policy allows to carry out this locality and produces, then add allowing local this locality of producing function to produce mark; Otherwise add this locality that does not allow this locality to produce function and produce mark;

2) agreement of signing between home network and the visited network operator: and if signed this locality between the visited network operator and produced agreement, then add allowing local this locality of producing function to produce mark; Otherwise add this locality that does not allow this locality to produce function and produce mark;

3) CAMEL-Subscription-Information: if the called subscriber produces the function contracted user for this locality, then add allowing local this locality of producing function to produce mark; Otherwise add this locality that does not allow this locality to produce function and produce mark;

4) the residing positional information of current calling and called both sides: if the calling subscriber is positioned at visited network, then add allowing local this locality of producing function to produce mark; Otherwise add this locality that does not allow this locality to produce function and produce mark;

5) network service state: if visited network is current to produce service for UE provides this locality, then add this locality that does not allow this locality to produce function and produce mark; Allow local this locality of producing function to produce mark otherwise add;

6) conversation media information that will initiate: as if the medium type of conversation media information, the requirement that coded format meets visited network, then add allowing local this locality of producing function to produce mark; Otherwise add this locality that does not allow this locality to produce function and produce mark.

S505)～S506) P-CSCF transmits above-mentioned session request (INVITE), and this request is transmitted through the PGW (PGW-1) of home network, arrives UE;

S507)～S508) after UE receives above-mentioned session request (INVITE), produce mark according to this locality that comprises in this request and know that permission uses this locality to produce function in this this session; If UE determines to use this locality to produce function according to terminal capability and preferred disposition, then in the request (Offer) of carrying out the session parameter negotiation was receiveed the response, adopting visited network was that its IP address allocated: IP-2 is as the medium routing address (i.e. Qing Qiu the employed address of SDP part) of current request; UE sends this request (Offer) and receives the response, and arrives P-CSCF through PGW-1;

Certainly, produce in this locality and to be labeled as when allowing this locality to produce, UE can select an IP address to carry out SDP negotiation arbitrarily.

S509)～S510) P-CSCF is receiveed the response according to above-mentioned session request (INVITE) and the request (Offer) that receives, carries out the resource reservation authentication;

Because the medium routing address during above-mentioned request (Offer) is receiveed the response is the IP address of visited network, therefore resource reservation relates to visited network, so this time the resource reservation authentication need be carried out alternately with PCRF (PCRF-1) server of visited network and PCRF (PCRF-2) server of home network;

Because UE needed to initiate the carrying registration to visited network before obtaining IP-2, in the process of registration, PCRF-1, PCRF-2 have preserved the binding relationship of UE and PCRF-1/PCRF-2/IP-2.Therefore, when P-CSCF and PCRF-1 carried out the resource reservation authentication alternately, PCRF-1 knew that according to IP-2 needs and PCRF-2 carry out the resource reservation authentication alternately.

S511)～S512) after the success of resource reservation authentication, P-CSCF should ask (Offer) to receive the response and be forwarded to S-CSCF, was transmitted to the calling subscriber by S-CSCF;

S513)～and S51 6) after the calling subscriber receives that above-mentioned request (Offer) is receiveed the response, confirm to consult successfully with UE, generate corresponding request (Offer) and respond and confirm, this message is through the forwarding of network elements such as S-CSCF, P-CSCF, PGW-1, arrival UE;

S517)～S518) UE receives that the above-mentioned request (Offer) that the calling subscriber sends responds after the acknowledge message, with the PCRF (PCRF-2) of the PGW (PGW-2) of visited network and visited network alternately, carry out resource reservation;

Equally, because UE needed to initiate the carrying registration to visited network before obtaining IP-2, in the process of registration, PGW-2 has preserved the binding relationship of UE and PCRF-1/PCRF-2/IP-2.Therefore, when UE and PGW-2 carried out the resource reservation authentication alternately, PGW-2 knew that according to IP-2 needs and PCRF-2 carry out the resource reservation authentication alternately.

S519) UE finishes after the resource reservation, sends the resource reservation acknowledge message to the calling subscriber; After UE receives calling subscriber's resource reservation acknowledge message, the beginning ring, after answering, beginning is set up media session between UE and calling subscriber, and this section flow process is similar to the S320～S346 of normal flow, omits herein;

S520)～S521) this moment, the session that the PGW (PGW-2) by visited network transmits was just set up between UE and calling subscriber.

Second embodiment

Fig. 6 is the implementation method flow chart of exhaling eventually in the second embodiment of the invention IMS network.In the present embodiment, UE roams into visited network, and the calling subscriber of this network that coexists initiates a session request to it; P-CSCF carries out this locality as decision point and produces the function decision-making, and adds this locality that does not allow to use this locality to produce function according to the result of decision in this session request and produce mark.Step is as follows among the figure:

S601) user terminal (UE) is under the roaming state, and this moment, the calling subscriber called out UE, and session request (INVITE) is sent on the current S-CSCF that service is provided for UE;

S602) S-CSCF is forwarded to this session request on the P-CSCF;

S603) P-CSCF receives after this session request, carries out obtaining this locality and producing policy information alternately with corresponding strategic server (for example, the PCRF:PCRF-1 of home network);

Above-mentioned this locality is produced policy information and is comprised: operator's local policy, and visited network operator between agreement, user's CAMEL-Subscription-Information, the residing positional information of current calling and called both sides, network service state and the conversation media information that will initiate etc.;

S604) P-CSCF produces policy information according to above-mentioned this locality and carries out this locality and produce the function decision-making, judge whether allow called subscriber (UE) to use the local service of breathing out in this session, and in this session request (INVITE), add corresponding this locality and produce mark;

In the present embodiment, the P-CSCF judgement does not allow UE to use this locality to produce service, and therefore corresponding this locality is produced and is labeled as: do not allow this locality to produce.

S605)～S606) P-CSCF transmits above-mentioned session request (INVITE), and this request is transmitted through the PGW (PGW-1) of home network, arrives UE;

S607)～S608) after UE receives above-mentioned session request (INVITE), produce mark according to this locality that comprises in this request and know and do not allow in this this session, to use this locality to produce function; Therefore in the request (Offer) of carrying out the session parameter negotiation was receiveed the response, adopting home network was that its IP address allocated: IP-1 is as the medium routing address (i.e. Qing Qiu the employed address of SDP part) of current request; UE sends this request (Offer) and receives the response, and arrives P-CSCF through PGW-1;

S609) P-CSCF is receiveed the response according to above-mentioned session request (INVITE) and the request (Offer) that receives, and is mutual with the PCRF (PCRF-1) of home network, carries out the resource reservation authentication;

S610)～S611) after the success of resource reservation authentication, P-CSCF should ask (Offer) to receive the response and be forwarded to S-CSCF, was transmitted to the calling subscriber by S-CSCF;

S612)～S615) after the calling subscriber receives that above-mentioned request (Offer) is receiveed the response, confirm to consult successfully with UE, generate corresponding request (Offer) and respond acknowledge message, this message is transmitted through network elements such as S-CSCF, P-CSCF, PGW-1, arrives UE;

S616)～S617) UE receives that the above-mentioned request (Offer) that the calling subscriber sends responds after the acknowledge message, with the PCRF (PCRF-1) of the PGW (PGW-2) of visited network and home network alternately, carry out resource reservation;

S618) UE finishes after the resource reservation, sends the resource reservation acknowledge message to the calling subscriber; After UE receives calling subscriber's resource reservation acknowledge message, the beginning ring, after answering, beginning is set up media session between UE and calling subscriber, and this section flow process is similar to the S320～S346 of normal flow, omits herein;

S619)～S620) this moment, the session that the PGW (PGW-1) by home network transmits was just set up between UE and calling subscriber.

In above-described embodiment, if among the step S604, P-CSCF allows called subscriber (UE) to use this locality to produce service, and in step S607, UE can determine not use this locality to produce function according to terminal capability and preferred disposition, and to adopt home network equally be its IP address allocated: IP-1 sends this request (Offer) as the medium routing address (i.e. Qing Qiu the employed address of SDP part) of current request and receive the response; All the other steps are identical.

The 3rd embodiment

Fig. 7 is the implementation method flow chart of exhaling eventually in the third embodiment of the invention IMS network.In the present embodiment, UE roams into visited network, and the calling subscriber of this network that coexists initiates a session request to it; S-CSCF carries out this locality as decision point and produces the function decision-making, and adds this locality that allows to use this locality to produce function according to the result of decision in this session request and produce mark, and UE uses this locality to produce function according to this mark.Step is as follows among the figure:

S701) user terminal (UE) is under the roaming state, and this moment, the calling subscriber called out UE, and session request (INVITE) is sent on the current S-CSCF that service is provided for UE;

S702) S-CSCF preserves or produces from this locality that other network element obtains policy information and carries out this locality and produce the function decision-making according to this locality, judge whether allow called subscriber (UE) to use the local service of breathing out in this session, and in this session request (INVITE), add corresponding this locality and produce mark;

In the present embodiment, S-CSCF judges that permission UE uses this locality to produce service, and therefore corresponding this locality is produced and is labeled as: allow this locality to produce.

S703) S-CSCF is forwarded to this session request on the P-CSCF;

S704) P-CSCF receives after this session request, if producing to be labeled as, this locality that comprises in this session request allow this locality to produce, then P-CSCF can with corresponding strategic server (for example, the PCRF:PCRF-1 of home network) carries out alternately, obtain this locality and produce policy information, produce the function decision-making in order to do further this locality;

In the present embodiment, P-CSCF also allows UE to use this locality to produce function, and namely mark is produced in this locality of not revising in the session request.

S705)～S706) P-CSCF transmits above-mentioned session request (INVITE), and this request is transmitted through the PGW (PGW-1) of home network, arrives UE;

S707)～S708) after UE receives above-mentioned session request (INVITE), produce mark according to this locality that comprises in this request and know that permission uses this locality to produce function in this this session; If UE determines to use this locality to produce function according to terminal capability and preferred disposition, then in the request (Offer) of carrying out the session parameter negotiation was receiveed the response, adopting visited network was that its IP address allocated: IP-2 is as the medium routing address (i.e. Qing Qiu the employed address of SDP part) of current request; UE sends this request (Offer) and receives the response, and arrives P-CSCF through PGW-1;

S709)～S710) P-CSCF is receiveed the response according to above-mentioned session request (INVITE) and the request (Offer) that receives, carries out the resource reservation authentication;

S711)～S712) after the success of resource reservation authentication, P-CSCF should ask (Offer) to receive the response and be forwarded to S-CSCF, was transmitted to the calling subscriber by S-CSCF;

S713)～S716) after the calling subscriber receives that above-mentioned request (Offer) is receiveed the response, confirm to consult successfully with UE, generate corresponding request (Offer) and respond acknowledge message, this message is transmitted through network elements such as S-CSCF, P-CSCF, PGW-1, arrives UE;

S717)～S718) UE receives that the above-mentioned request (Offer) that the calling subscriber sends responds after the acknowledge message, with the PCRF (PCRF-2) of the PGW (PGW-2) of visited network and visited network alternately, carry out resource reservation;

S719) UE finishes after the resource reservation, sends the resource reservation acknowledge message to the calling subscriber; After UE receives calling subscriber's resource reservation acknowledge message, the beginning ring, after answering, beginning is set up media session between UE and calling subscriber, and this section flow process is similar to the S320～S346 of normal flow, omits herein;

S720)～S721) this moment, the session that the PGW (PGW-2) by visited network transmits was just set up between UE and calling subscriber.

The 4th embodiment

Fig. 8 is the implementation method flow chart of exhaling eventually in the fourth embodiment of the invention IMS network.In the present embodiment, UE roams into visited network, and the calling subscriber of this network that coexists initiates a session request to it; AS carries out this locality as decision point and produces the function decision-making, and adds this locality that allows to use this locality to produce function according to the result of decision in this session request and produce mark, and UE uses this locality to produce function according to this mark.Step is as follows among the figure:

S801) user terminal (UE) is under the roaming state, and this moment, the calling subscriber called out UE, and session request (INVITE) is sent on the current S-CSCF that service is provided for UE;

S802) S-CSCF is forwarded to this session request on the AS;

S803) AS preserves or produces from this locality that other network element obtains policy information and carries out this locality and produce the function decision-making according to this locality, judge whether allow called subscriber (UE) to use the local service of breathing out in this session, and in this session request (INVITE), add corresponding this locality and produce mark;

In the present embodiment, AS judges that permission UE uses this locality to produce service, and therefore corresponding this locality is produced and is labeled as: allow this locality to produce.

S804) AS is forwarded to S-CSCF with this session request;

S805) S-CSCF is forwarded to this session request on the P-CSCF;

S806) P-CSCF receives after this session request, if producing to be labeled as, this locality that comprises in this session request allow this locality to produce, then P-CSCF can with corresponding strategic server (for example, the PCRF:PCRF-1 of home network) carries out alternately, obtain this locality and produce policy information, produce the function decision-making in order to do further this locality;

S807)～S808) P-CSCF transmits above-mentioned session request (INVITE), and this request is transmitted through the PGW (PGW-1) of home network, arrives UE;

S809)～S810) after UE receives above-mentioned session request (INVITE), produce mark according to this locality that comprises in this request and know that permission uses this locality to produce function in this this session; If UE determines to use this locality to produce function according to terminal capability and preferred disposition, then in the request (Offer) of carrying out the session parameter negotiation was receiveed the response, adopting visited network was that its IP address allocated: IP-2 is as the medium routing address (i.e. Qing Qiu the employed address of SDP part) of current request; UE sends this request (Offer) and receives the response, and arrives P-CSCF through PGW-1;

S811)～S812) P-CSCF is receiveed the response according to above-mentioned session request (INVITE) and the request (Offer) that receives, carries out the resource reservation authentication;

S813)～S814) after the success of resource reservation authentication, P-CSCF should ask (Offer) to receive the response and be forwarded to S-CSCF, was transmitted to the calling subscriber by S-CSCF;

S815)～S818) after the calling subscriber receives that above-mentioned request (Offer) is receiveed the response, confirm to consult successfully with UE, generate corresponding request (Offer) and respond acknowledge message, this message is transmitted through network elements such as S-CSCF, P-CSCF, PGW-1, arrives UE;

S819)～S820) UE receives that the above-mentioned request (Offer) that the calling subscriber sends responds after the acknowledge message, with the PCRF (PCRF-2) of the PGW (PGW-2) of visited network and visited network alternately, carry out resource reservation;

S821) UE finishes after the resource reservation, sends the resource reservation acknowledge message to the calling subscriber; After UE receives calling subscriber's resource reservation acknowledge message, the beginning ring, after answering, beginning is set up media session between UE and calling subscriber, and this section flow process is similar to the S320～S346 of normal flow, omits herein;

S822)～S823) this moment, the session that the PGW (PGW-2) by visited network transmits was just set up between UE and calling subscriber.

Based on principle of the present invention, above-described embodiment can also carry out multiple conversion, for example:

Mark is produced except allowing this locality to produce and do not allow this locality produces in this locality, can also be to use this locality to produce; In this case, no matter whether the preferred disposition of UE is to use this locality to produce function, as long as terminal capability allows, and has obtained visited network and is its IP address allocated, just must use this locality to produce function.

Claims

1. the implementation method of exhaling eventually in the IP Multimedia System, it is characterized in that, when calling terminal initiates a session request to the terminal called that roams into visited network, the IMS network element that receives this session request judges whether to allow this terminal called to use this locality to produce function in the session of this session request correspondence, and adds in this session request according to judged result and after mark is produced in corresponding this locality this session request to be forwarded to described terminal called;

Wherein, this locality is produced mark and is comprised: allow this locality to produce, must use this locality to produce and do not allow to produce;

The IMS network element that carries out described judgement is one or more in the following network element: the P-CSCF in the described session request forward-path, the S-CSCF in the described session request forward-path, the AS that links to each other with described S-CSCF.

2. the method for claim 1 is characterized in that, described calling terminal is positioned at described visited network.

3. the method for claim 1 is characterized in that, if AS carries out described judgement, then described S-CSCF is after receiving described session request, this request is sent to AS, after AS finishes described judgement, this session request is transmitted to described terminal called by described S-CSCF.

4. the method for claim 1 is characterized in that,

Described IMS network element produces policy information according to this locality and carries out described judgement; Described this locality produce policy information comprise following one or more: operator's local policy, the agreement of signing between home network and the visited network operator, called user subscription information.

5. the method for claim 1 is characterized in that,

When comprising this locality that does not allow this locality to produce in the described session request that receives and produce mark, described terminal called uses home network to carry out session parameter for its IP address allocated as the medium routing address and consults.

6. method as claimed in claim 5, it is characterized in that, when the request that being used for of receiving that described terminal called sends, session parameter consulted is receiveed the response, if the medium routing address in this message is the IP address of described visited network, then the PCRF of P-CSCF and home network and visited network is mutual, carries out the resource reservation authentication; Otherwise the PCRF of P-CSCF and home network is mutual, carries out the resource reservation authentication.

7. the method for claim 1 is characterized in that, described session request is INVITE.

8. method as claimed in claim 7 is characterized in that, described this locality is produced and is labeled as header field newly-increased in the described session request or the label in newly-increased or the existing header field.