CN101137104A

CN101137104A - Method and system for implementing resource release

Info

Publication number: CN101137104A
Application number: CNA2006101115826A
Authority: CN
Inventors: 杨伟强
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2006-08-28
Filing date: 2006-08-28
Publication date: 2008-03-05
Anticipated expiration: 2026-08-28
Also published as: CN101137104B; WO2008025216A1

Abstract

This method includes: (1) After receiving the conversation building request message (CBR) not including the Supported Head-Domain with Timer-Mark (SHT), the back-to-back user agent unit (BUA) adds SHT into the request message. (2) All node-devices (ND) negotiate to appoint the renewing node-devices (RN) and decide that except RN, all other node-devices on the conversation path (CP) do not start CBR. (3) After the conversation built, every RN respectively starts the conversation renewing request message (CRR) toward the connecting NDs on its both sides on CP. This scheme solves the problems of the meaningless transferring CRR and the messages collision during the conversation procedure. It enables the resource to release even if both calling/called terminals do not support the Session Timers protocol. This invention also discloses simultaneously a system realizing resource release.

Description

A kind of method and system of realizing that resource discharges

Technical field

The present invention relates to communication technical field, particularly a kind of method and system of realizing that resource discharges.

Background technology

In recent years, along with the development of mobile communication technology, single voice communication mode can not satisfy user's needs fully, and brand-new multimedia communication mode just continues to bring out.These multimedia communications are not only simple video, voice communication, also comprise instant message, with the location browse, collaborative work, Streaming Media etc., the business that particularly new communication mode and traditional voice merge is mutually more accepted by masses.Numerous merging in the conversation control system based on the Internet and communication network, most of conversation control systems all adopt initial session protocol (SIP) as session control protocol, and the most representative is exactly internet protocol multimedia subsystem (IMS).

IMS is the voice-and-data service system, and it can be according to user data, shielding user's access way, and the degree of opening of control professional ability, thus multimedia communication experiences is provided.And the IMS that combines voice, data and multimedia innovation and application can produce the demand to new service, such as presence service, multimedia chat, meeting, push-to-talk and button meeting etc.

Main function comprises the calling control (CSCF) of functions such as control user registration, session control and the MGCF/IMS medium gateway function (MGCF/IM-MGW) of realization and circuit switching net interconnecting among the IMS.

Main equipment comprises application server (AS) that miscellaneous service logic control function is provided and the home subscriber server (HSS) that is used to manage concentratedly user contracting data among the IMS.

Wherein, CSCF is divided into according to function in network: the home domain service node (S-CSCF) of current location agent node (P-CSCF), registered place and inquire node (I-CSCF).P-CSCF is the access point of user in the IMS system, and all must be through P-CSCF from UE or the SIP signaling flow that mails to UE.I-CSCF is connected to the communication center that the user of this operator provides for all in a carrier network.S-CSCF is in the control core status in the IMS core net, it is positioned at home network.Be responsible for register and authentication and session control, carry out basic session routing function, and trigger corresponding rule according to the IMS that the user contracts at calling terminal and called end IMS user to UE.

The user inserts IMS by current location agent node P-CSCF, and session is then finished by the home domain service node S-CSCF of its registered place alternately with professional triggering control with the business control of AS; IMS adopts Session Initiation Protocol as the mutual signaling of application layer, and the interface protocol between terminal and the CSCF, between the CSCF, between CSCF and the AS is Session Initiation Protocol.But Session Initiation Protocol does not define a kind of agreement and makes whether intermediate node can detection session in time be in active state after session is set up, this causes under the situation of terminal transmission release Indication message failure, and the intermediate node in the IMS system may make resource discharge.Session timing (Session Timers) agreement then be at this problem to the replenishing of Session Initiation Protocol, be an expansion of Session Initiation Protocol.This Session Timers agreement allows certain terminal in the session be responsible for periodic initiation session update request to be in active state to guarantee session, do not send failure if receive session updates request or session updates request in the cycle, show that then session has been in inactive state, this terminal discharges related resource so.Intermediate node in the IMS system, for example P-CSCF or S-CSCF then directly discharge this session related resource in overtime back.So just guaranteed the timely release of related resource.

According to the regulation of Session Timers agreement, for realizing very easily that as the node of acting server (PROXY) for example P-CSCF and S-CSCF are usually only as the PROXY unit.But it is this usually as back-to-back user agent (B2BUA) unit for AS, Session Timers agreement is not stipulated, if directly apply arbitrarily this agreement, in the process of session, insignificant forwarding is carried out repeatedly in the session updates request or bumped, can't realize smoothly, so the resource of B2BUA unit discharges problem and does not also solve well.

Figure 1A sends the schematic flow sheet of the meaningless forwarding of session updates request for calling terminal.

Step 100, calling terminal send session to B2BUA Unit 1 and set up request message.

The session that calling terminal sends is set up and is comprised session termination (Session-Expires) header field in the request message, also may comprise support (supported:timer) header field and/or the minimum session of being with time tag and stop (Min_SE) header field.

If between calling terminal and the B2BUA 1 the PROXY unit is arranged, then the PROXY unit is set up request message with the session of receiving and is transmitted.

Step 101, B2BUA Unit 1 receive that session sets up the relevant treatment that request message carries out Session Timers agreement regulation.

Subscriber proxy server (UAS) end of B2BUA Unit 1 checks in the message whether have the supported:timer header field.

If setting up, session has the supported:timer header field in the request message, and the value of Session-Expires header field is less than the value of local Min_SE header field, then to calling terminal reply show response that session updates is too short at interval and in response with on the value of local Min_SE header field, calling terminal is received and is replied the value that the value of Session-Expires header field is not less than instead after the response Min_SE header field, sends to B2BUA Unit 1 again.

If setting up, session do not have the supported:timer header field in the request message, and the value of Session-Expires header field is less than the value of local Min_SE header field, when the Min_SE header field is arranged in message, the value of Min_SE header field in the request message is increased to equates with the value of local Min_SE header field and as the value of Session-Expires header field, when in message, not having the Min_SE header field, in request message, insert the Min_SE header field, its value is the value of local Min_SE header field, and will be worth the value as the Session-Expires header field.

No matter session sets up in the request whether have the supported:timer header field, as long as the value of Session-Expires header field is not less than the value of local Min_SE header field, then can the value of Session-Expires not carried out any modification, also can be in being not less than message the Min_SE header field value and be not less than the value that suitably reduces the Session-Expires header field on the basis of value of local Min_SE header field.

Session after user agent client (UAC) end of B2BUA Unit 1 is handled according to the UAS end is set up the new session of request message structure and is set up request message.

Session after step 102, B2BUA Unit 1 will be handled is set up request message and is sent to the PROXY unit.

If a plurality of PROXY unit, then each PROXY unit is all set up request message with session and is transmitted; If there is not the PROXY unit, then B2BUA 1 is directly set up session request message and is sent to B2BUA 2.

Step 103, PROXY unit are set up request message with the session of receiving and are sent to AS (B2BUA Unit 2).

Step 104, B2BUA Unit 2 receive that session sets up the relevant treatment that request message carries out Session Timers agreement regulation.

Processing procedure is identical with the processing procedure of step 101.

Session after step 105, B2BUA Unit 2 will be handled is set up request message and is sent to terminal called.

If the PROXY unit is arranged between B2BUA 2 and the terminal called, then the PROXY unit is set up request message with the session of receiving and is transmitted.

Step 106, terminal called send 200 response messages of representing successfully to B2BUA Unit 2.

If the PROXY unit is arranged between B2BUA 2 and the terminal called, then 200 response messages that will receive of PROXY unit are transmitted.

Step 107, B2BUA Unit 2 receive that 200 response messages carry out the relevant treatment of Session Timers agreement regulation.

The UAC end of B2BUA Unit 2 is according to the time and furbisher (refresher) parameter of Session-Expires header field in the response message, session negotiation is made as uac with the furbisher, so the UAC of B2BUA Unit 2 holds device when starting initiation session update request timer and overtime release timer.

The device when UAS of B2BUA Unit 2 end starts overtime release timer according to the value of Session-Expires header field.

For being made as uac, so the UAS of B2BUA Unit 2 end does not start and sends session updates request timer with the furbisher in session negotiation.

200 response messages after step 108, B2BUA Unit 2 will be handled send to the PROXY unit.

200 response messages that step 109, PROXY unit will be received send to AS (B2BUA Unit 1).

If a plurality of PROXY unit, then each PROXY unit is all transmitted message; If there is not the PROXY unit, then B2BUA 2 directly sends to message B2BUA 1.

Step 110, B2BUA Unit 1 receive that 200 response messages carry out the relevant treatment of Session Timers agreement regulation.

Processing procedure is identical with the processing procedure of step 107.

200 response messages that step 111, B2BUA Unit 1 will be handled send to calling terminal.

After calling terminal was received 200 response messages, session was successfully set up, and Session Timers also consults success simultaneously.The session updates timer of calling terminal starts timing.

Step 112, the parameter refresher that determines when consulting are uac, calling terminal is responsible for the initiation session update request, and the session updates timer of calling terminal has been crossed (Session Expires/2) second notice calling terminal and sent the session updates request to B2BUA Unit 1 so.

Step 113, the parameter refresher that determines when consulting are uac, the UAC end of B2BUA Unit 1 is responsible for the initiation session update request, and the UAC end that the session updates timer of B2BUA Unit 1 has been crossed (SessionExpires/2) second notice B2BUA Unit 1 sends the session updates request to the PROXY unit.

Step 114, B2BUA Unit 1 carry out the session updates request that calling terminal sends relevant treatment and send to the PROXY unit.

Step 115, PROXY unit send to AS (B2BUA Unit 2) with the session updates request that B2BUA Unit 1 sends.

Step 116, PROXY unit send to AS (B2BUA Unit 2) with the session updates request that B2BUA Unit 1 sends.

Step 117, the parameter refresher that determines when consulting are uac, the UAC end of B2BUA Unit 2 is responsible for the initiation session update request, and the session updates timer of B2BUA Unit 2 has been crossed (SessionExpires/2) second notice B2BUA Unit 2 and sent the session updates request to terminal called.

Step 118, B2BUA Unit 2 carry out the session updates request that the PROXY unit sends relevant treatment and send to terminal called.

Step 119, B2BUA Unit 2 carry out the session updates request that the PROXY unit sends relevant treatment and send to terminal called.

Figure 1B sends the collision schematic flow sheet of session updates request for calling terminal.

Step 1000, calling terminal send session to B2BUA Unit 1 and set up request message.

Step 1001, B2BUA Unit 1 receive that session sets up the relevant treatment that request message carries out Session Timers agreement regulation.

The UAS end of B2BUA Unit 1 checks in the message whether have the supported:timer header field.

If setting up, session do not have the supported:timer header field in the request message, the expression calling terminal is not supported Session Timers agreement, and the value of Session-Expires header field is less than the value of local Min_SE header field, when the Min_SE header field is arranged in message, the value of Min_SE header field in the request message is increased to equates with the value of local Min_SE header field and as the value of Session-Expires header field, when in message, not having the Min_SE header field, in request message, insert the Min_SE header field, its value is the value of local Min_SE header field, and will be worth the value as the Session-Expires header field.

No matter session sets up whether have the supported:timer header field in the request message, as long as the value of Session-Expires header field is not less than the value of local Min_SE header field, then can the value of Session-Expires not carried out any modification, also can be in being not less than message the Min_SE header field value and be not less than the value that suitably reduces the Session-Expires header field on the basis of value of local Min_SE header field.

The UAC end of B2BUA Unit 1 is according to the new request message of UAS end processed request message constructing.

Session after step 1002, B2BUA Unit 1 will be handled is set up request message and is sent to the PROXY unit.

Step 1003, PROXY unit are set up request message with the session of receiving and are sent to AS (B2BUA Unit 2).

Step 1004, B2BUA Unit 2 receive that request message carries out the relevant treatment of Session Timers agreement regulation.

Processing procedure is identical with the processing procedure of step 1001.

Session after step 1005, B2BUA Unit 2 will be handled is set up request message and is sent to terminal called.

Step 1006, terminal called send 200 response messages of representing successfully to B2BUA Unit 2.

The relevant treatment that 200 response messages are stipulated is received in step 1007, B2BUA Unit 2.

The UAC end of B2BUA Unit 2 is according to the time and the refresher parameter of Session-Expires header field in the response message, refresher between session negotiation B2BUA 2 and the terminal called is set to refresher=uac, so the UAC of B2BUA Unit 2 end starts session updates timer and session timeout release timer.

The UAS end of B2BUA Unit 2 starts relevant timer according to the value of Session-Expires header field with the refresher parameter.

Refresher between session negotiation B2BUA 1 and the B2BUA 2 is set to refresher=uas, so the UAS of B2BUA Unit 2 end starts session updates timer and session timeout release timer.

200 response messages after step 1008, B2BUA Unit 2 will be handled send to the PROXY unit.

200 response messages that step 1009, PROXY unit will be received send to AS (B2BUA Unit 1).

Step 1010, B2BUA Unit 1 receive that 200 response messages carry out the relevant treatment of Session Timers agreement regulation.

The UAC end of B2BUA Unit 1 starts relevant timer according to the time and the refresher parameter of Session-Expires header field in the response message.

Refresher between session negotiation B2BUA 1 and the B2BUA 2 is set to refresher=uas, so the UAC of B2BUA Unit 1 end does not start session updates timer and session timeout release timer.

The UAS end of B2BUA Unit 1 starts relevant timer according to the value of Session-Expires header field with the refresher parameter.

Refresher between session negotiation B2BUA 1 and the B2BUA 2 is set to refresher=uas, so the UAS of B2BUA Unit 2 end does not start session updates timer and session timeout release timer.

200 response messages that step 1011, B2BUA Unit 1 will be handled send to calling terminal.

Step 1012, the parameter refresher that determines when consulting, calling terminal is to refresher=uac between the B2BUA 1, refresher=uas between B2BUA 1 and the B2BUA 2, refresher=uac between B2BUA 2 and the terminal called, calling terminal is responsible for the initiation session update request so, and the session updates timer of calling terminal has been crossed (SessionExpires/2) second notice calling terminal and sent the session updates request to B2BUA Unit 1.

Step 1013, B2BUA Unit 1 carry out the session updates request that calling terminal sends relevant treatment and send to the PROXY unit.

Step 1014, PROXY unit send to AS (B2BUA Unit 2) with the session updates request that B2BUA Unit 1 sends.

Step 1015, B2BUA Unit 2 carry out the session updates request that the PROXY unit sends relevant treatment and send to terminal called.

Step 1016, the parameter refresher that determines when consulting, calling terminal is to refresher=uac between the B2BUA 1, refresher=uas between B2BUA 1 and the B2BUA 2, refresher=uac between B2BUA 2 and the terminal called, the initiation session update request is responsible in B2BUA Unit 2 so, and the session updates timer of B2BUA Unit 2 has been crossed (SessionExpires/2) second notice B2BUA Unit 2 and sent the session updates request to the PROXY unit.

Step 1017, PROXY unit send to AS (B2BUA Unit 1) with the session updates request that B2BUA Unit 2 send.

Step 1018, B2BUA Unit 1 carry out the session updates request that the PROXY unit sends relevant treatment and send to calling terminal.

Step 1019, the parameter refresher that determines when consulting, calling terminal is to refresher=uac between the B2BUA 1, refresher=uas between B2BUA 1 and the B2BUA 2, refresher=uac between B2BUA 2 and the terminal called, the initiation session update request is responsible in B2BUA Unit 2 so, and the session updates timer of B2BUA Unit 2 has been crossed (SessionExpires/2) second notice B2BUA Unit 2 and sent the session updates request to terminal called.

As can be seen, on B2BUA Unit 1, the session updates request of step 1012 and step 1017 bumps from Figure 1B, and the unnecessary session updates request of B2BUA 1 unit forwards.

Also may send the session updates request in the prior art from terminal called, then calling terminal is to refresher=uas between the B2BUA 1, refresher=uac between B2BUA 1 and the B2BUA 2, refresher=uas between B2BUA 2 and the terminal called, the session updates request bumps the session updates request that B2BUA 2 unit forwards are unnecessary near B2BUA Unit 2.

In sum, in the prior art, if session is in inactive state, need to discharge Session Resources, require calling terminal or terminal called to have at least one to support Session Timers agreement, the session updates request of sending by the calling terminal of supporting the SessionTimers agreement or terminal called.If calling terminal or terminal called are not supported Session Timers agreement, each B2BUA unit can't be released to the resource that this session distributes.

And, if send the session updates request by calling terminal, after then the session updates request is received in each B2BUA unit, since can't judge current this request message be session updates please or common service negotiation message, therefore all generate a new session update request, and session updates request and the new session update request of receiving sent to next B2BUA unit that institute's approach is set up in session, until terminal called.Equally, if send the session updates request, after then the session updates request is received in each B2BUA unit, also all the session updates request of receiving and the new session update request of generation are sent to Calling Side, until calling terminal by terminal called.Therefore, because the session updates request can be transmitted and initiate in each B2BUA unit all, end user's terminal can be received a large amount of insignificant session updates requests, if the B2BUA unit sends new session updates request to both sides after receiving the session updates request, also can cause the collision of session updates request.

Summary of the invention

Main purpose of the present invention provides a kind of method and system of realizing that resource discharges, and it is not supported in terminal under the situation of SessionTimers agreement, when session is in inactive state, can realize that resource discharges.

Another object of the present invention provides a kind of back-to-back user agent device, is applied in the resource delivery system, when terminal is not supported Session Timers agreement, if session is in inactive state, can realize that resource discharges.

A kind of method that realizes that resource discharges provided by the invention comprises:

After receiving that request message is set up in session, judge the support Supported header field that wherein whether contains band time timer label, if, request message is set up in this session to forward, otherwise, in this message, increase the Supported header field of band timer label, and request message is set up in this session forwarded.

Set up in the process in session, this method may further include: carry out furbisher's negotiation between the node device, determine that a node device is the furbisher; After session is set up, by consulting to be defined as furbisher's node device to other network nodes transmission session updates requests.

After session is set up, this method can also comprise: after each node device is received the session updates request, judge the Supported header field that whether contains band timer label in the session updates request, if then only send the session updates request to the next node equipment of session institute approach according to the session updates request of receiving.

Carry out furbisher's negotiation between the described node device, determine that a node device can comprise for furbisher's step:

The session that A11, B2BUA unit are set up in the request message in this session that node device from institute's approach to session that set up is transmitted stops adding in the Session-Expires header field furbisher's parameter, furbisher refresher is set to User Agent Client uac, is used to show that this B2BUA unit is responsible for to terminal called initiation session update request;

After A12, this B2BUA unit receive that response message is set up in session, then in the Session-Expires header field of setting up to the session of calling terminal answer in the response message, add furbisher's parameter, refresher is set to subscriber proxy server end uas, is used to show that this B2BUA unit is responsible for to calling terminal initiation session update request.

The node device that A21, B2BUA unit set up institute's approach to session sends this session and sets up request message, the Supported header field that wherein contains band timer label, after each node device receives that request message is set up in this session, transmit to next node device, up to terminal called;

After A22, terminal called receive that request message is set up in this session, if determine certainly as the furbisher, then return session to this B2BUA and set up response message by node device, wherein the Session-Expires header field is uas, if determine self not to be the furbisher, then return self to this B2BUA and do not set up response message for furbisher's session by node device;

After A23, this B2BUA unit receive that response message is set up in session, judge whether terminal called is the furbisher, if, execution in step A24, otherwise, with self as the furbisher, execution in step A24;

A24, this B2BUA unit are set up in the session of replying to calling terminal and are added furbisher's parameter in the response message in the Session-Expires header field, and refresher is set to subscriber proxy server end uas.

Self does not set up response message for furbisher's session and can set up response message for the session that does not contain the Supported header field of being with the timer label in steps A 22;

Self does not set up response message for furbisher's session and can set up response message for the session that contains the Supported header field of being with the timer label in steps A 22, and wherein the refresher of Session-Expires header field is uas.

A kind of system that realizes that resource discharges provided by the invention comprises: one or more B2BUA unit, wherein, each B2BUA unit, be used to receive set up request message from the session of a last node device after, judge that this session sets up the Supported header field that whether carries the timer label in the request message, if contain, request message is set up in this session to be transmitted to next node device, otherwise, set up the Supported header field that adds band timer label in the request message in session, request message is set up in this session transmitted to next node device; After session is set up,, discharge the resource of distributing from as this session if determine that this session is in inactive state.

The B2BUA unit can be further used for: after session is set up, if receive the session updates request, whether judge in the session updates request Supported header field with the timer label, if then only send the session updates request to next network node of session institute approach according to the session updates request of receiving.

Wherein, the B2BUA unit can comprise:

The session protocol judge module, be used for judging that the session of receiving sets up request message whether with the Supported header field of timer label, if, directly request message being set up in this session forwards, otherwise, set up the Supported header field that adds band timer label in the request message in this session, request message is set up in this session forwarded;

The resource release module is used for judging according to the session updates response message of receiving whether session status is normal, is in inactive state in this session, discharges the resource of distributing from as this session.

The B2BUA unit further further comprises:

Furbisher's negotiation module is used for this session set up and adds furbisher's parameter in the Session-Expires header field of request message, and sets up response message according to the session of receiving and determine whether self is the furbisher;

The session updates request module is used for after session is set up, and sets up the network node initiation session update request of institute's approach if determine respectively to this session of both sides from as the furbisher; If determine it self is not the furbisher, whether judge in the session updates request of receiving Supported header field, if then only send session updates request to next network node of session institute approach with the timer label.

A kind of back-to-back user agent device provided by the invention comprises:

The B2BUA device may further include:

The present invention consults determined B2BUA unit to calling terminal and terminal called initiation session update request by the furbisher, realized that calling terminal and terminal called do not support can realize under the situation of Session Timers agreement that resource discharges yet, cancel the initiatively behavior of initiation session update request of other B2BUA unit, after receiving the session updates request, only transmitted this request.Avoided the problem of session updates request insignificant forwarding and collision in the conversation procedure.

Description of drawings

Figure 1A sends the schematic flow sheet of the meaningless forwarding of session updates request for calling terminal;

Figure 1B sends the schematic flow sheet of the session updates request collision of session updates request for calling terminal;

The system configuration schematic diagram of Fig. 2 for realizing that resource of the present invention discharges;

Fig. 3 is the structural representation of B2BUA device of the present invention;

Fig. 4 realizes the schematic flow sheet of method for releasing resource for the present invention;

Fig. 5 A is the schematic flow sheet of the specific embodiment one of realization the inventive method;

Fig. 5 B is the schematic flow sheet of the specific embodiment two of realization the inventive method;

Fig. 6 is the schematic flow sheet of the specific embodiment three of realization the inventive method;

Fig. 7 is the schematic flow sheet of the specific embodiment four of realization the inventive method.

Embodiment

At at present in communication technical field, realize on the B2BUA unit that Session Timers agreement exists the session updates solicited message that repeatedly insignificant forwarding and collision problem take place, the present invention has solved the problems referred to above by the function of removing B2BUA unit active initiation session update request.And session is set up in the process, by changing the B2BUA unit, make it can be initiatively to calling terminal and terminal called initiation session update request, thereby realized not supporting also can successfully set up Session Timers agreement under the situation of Session Timers agreement at calling terminal and terminal called.

Set up in the process in session, the B2BUA unit receives after session sets up request message, judge that this session sets up the support Supported header field that whether contains band time timer label in the request message,, then directly this session is set up request message and transmit to next node device if contain; If do not contain, then set up the Supported header field that adds band timer label in the request message in this session, the session that will increase the Supported header field of band timer label is again set up request message to next node device forwarding.

Set up in the process in session, can also carry out furbisher's negotiation between the node device.After session is set up, by consulting determined furbisher respectively to the node device initiation session update request of this session institute approach of the both sides that are connected with self.After each node device is received the session updates request, according to the session updates request of receiving upstream or the downstream send the session updates request, until calling terminal and terminal called; Each node device is under the situation of inactive state in definite this session, discharges the resource of distributing from as this session.

After session is set up, when the B2BUA unit receives after session sets up request message, if determine to contain in the message Supported header field of band timer label, then not regeneration session updates request, only the next node equipment to session institute approach sends the session updates request.

The system configuration schematic diagram of Fig. 2 for realizing that resource of the present invention discharges.As shown in Figure 2, system of the present invention comprises: one or more B2BUA unit,

Each B2BUA unit, after being used to receive session foundation request from a last node device, judge the Supported header field that whether carries the timer label in this session foundation request, if contain, request message is set up in this session to be transmitted to next node device, otherwise, set up the Supported header field that adds band timer label in the request message in session, request message is set up in this session transmitted to next node device; After session is set up,, discharge the resource of distributing from as this session if determine that this session is in inactive state.

After session is set up, if the session updates request is received in the B2BUA unit, whether the B2BUA unit also is further used for judging in the session updates request Supported header field with the timer label, if then only send the session updates request to next network node of session institute approach according to the session updates request of receiving.

As shown in Figure 3, B2BUA of the present invention unit comprises: session protocol judge module and resource release module.Wherein, the session protocol judge module, be used for judging that the session of receiving sets up request message whether with the Supported header field of timer label, if, directly request message being set up in this session forwards, otherwise, set up the Supported header field that adds band timer label in the request message in this session, request message is set up in this session forwarded; The source release module is used for judging according to the session updates response message of receiving whether session status is normal, is in inactive state in this session, discharges the resource of distributing from as this session.

Certainly, in order to carry out furbisher's negotiation, the B2BUA unit further further comprises: furbisher's negotiation module and session updates request module.Wherein, furbisher's negotiation module, the session that is used for this session is set up request message stops adding furbisher's parameter in the Session-Expires header field, and sets up response message according to the session of receiving and determine whether self is the furbisher; The session updates request module is used for after session is set up, and sets up the network node initiation session update request of institute's approach if determine respectively to this session of both sides from as the furbisher; If determine it self is not the furbisher, whether judge in the session updates request of receiving Supported header field, if then only send session updates request to next network node of session institute approach with the timer label.

Fig. 4 is for to receive that with the first B2BUA unit session updates request is an example, and the present invention realizes the schematic flow sheet that resource discharges.Wherein, the first B2BUA unit receives that for set up in the process first in session session sets up the B2BUA unit of request message, and all the other the B2BUA unit and the first B2BUA element method are similar, no longer give an example.

Referring to shown in Figure 4, the present invention realizes that the method that resource discharges comprises:

After step 400, the first B2BUA unit receive that request message is set up in session, judge the Supported header field that whether contains band timer label in the message, if having, show that calling terminal is to support Session Timers agreement, then execution in step 401; Otherwise, directly this conversation request is transmitted to next node device, up to terminal called, execution in step 407.

After step 401, the first B2BUA unit receive that request message is set up in session, the UAC of first B2BUA unit end is set up in session and is inserted the supported:timer header field in the request message, and session is set up, and refresher is set to uac in the Session-Expires header field in the request message.

Step 402, the first B2BUA unit send the session of increase supported:timer header field to next B2BUA unit and set up request message.

After step 403, each B2BUA unit receive that request message is set up in session, directly session is set up request message and send to next node equipment, up to terminal called.

After step 404, terminal called receive that request message is set up in session, return session to connected B2BUA unit and set up response message, after each B2BUA unit receives that request message is set up in session, only start the session timeout release timer, and response message is set up in session sent to upper level B2BUA unit, up to the first B2BUA unit.

After step 405, the first B2BUA unit receive that response message is set up in this session, if determine certainly as the furbisher, then set up and insert the supported:timer header field in the response message in session, and the parameter refresher in the Session-Expires header field is set to refresher=uas, and response message is set up in this session sent to calling terminal.

Step 406, behind call setup, the first B2BUA unit is to both sides initiation session update request.

After the session updates request is received in step 407, each B2BUA unit, judge the Supported header field that whether contains band timer label in the session updates request, if have, and directly transmit this session updates request to next node device, here do not produce new session updates request, execution in step 410.

After step 408, terminal called receive that request message is set up in session, return session to connected B2BUA unit and set up response message, after each B2BUA unit receives that request message is set up in session, only start the session timeout release timer, and response message is set up in session sent to upper level B2BUA unit, up to the first B2BUA unit.

Step 409, behind call setup, send session updates request, execution in step 410 by calling terminal or terminal called to coupled B2BUA unit.

Step 410, when each B2BUA unit determines that session is inactive state, discharge the resource of distributing from as this session.

The process that above-mentioned steps 401～405 is consulted for the furbisher.

Node device can carry out furbisher's negotiation according to s own situation, determines from as brush side.

For example: the first B2BUA unit and terminal called carry out furbisher's negotiations process can be realized by following dual mode.

First kind of mode:

(1) the B2BUA unit adds furbisher's parameter in Session-Expires header field in the request message is set up in this session that node device from institute's approach to session that set up is transmitted, furbisher refresher is set to User Agent Client uac, is used to show that this B2BUA unit is responsible for to terminal called initiation session update request;

(2) after terminal called receives that request message is set up in this session, determine that self is not the furbisher, then returns to this B2BUA by node device and self does not set up response message for furbisher's session;

(3) after this B2BUA unit receives that response message is set up in this session, determine certainly as the furbisher, then add furbisher's parameter in the Session-Expires header field of setting up to the session of calling terminal answer in the response message, refresher is set to subscriber proxy server end uas.

The second way:

(1) B2BUA unit node device from institute's approach to session that set up sends this session and sets up request message, the Supported header field that wherein contains band timer label, after each node device receives that request message is set up in this session, transmit to next node device, up to terminal called;

(2) after terminal called receives that request message is set up in this session, if determine certainly as the furbisher, then return session to this B2BUA and set up response message by node device, wherein the Session-Expires header field is uas, if determine self not to be the furbisher, then return self to this B2BUA and do not set up response message for furbisher's session by node device;

(3) after this B2BUA unit receives that response message is set up in session, judge whether terminal called is the furbisher, if, execution in step (4), otherwise, with self as the furbisher, execution in step (4);

(4) this B2BUA unit is set up in the session of replying to calling terminal and is added furbisher's parameter in the response message in the Session-Expires header field, and refresher is set to subscriber proxy server end uas.

For the ease of understanding the present invention, below lift instantiation and further specify technical scheme of the present invention.

Shown in Fig. 5 A, present embodiment one realizes that the handling process of resource release is as follows:

The present embodiment furbisher is a B2BUA 1, by B2BUA 1 to caller and terminal called initiation session update request.

Step 500, calling terminal send session to B2BUA Unit 1 and set up request message.

Step 501, B2BUA Unit 1 receive that session sets up request message, and the UAS end of B2BUA Unit 1 checks in the message whether be with the supported:timer header field.

If session is set up the supported:timer header field is arranged in the request message, then jump out this flow process, otherwise, this message is carried out the processing of Session Timers agreement.

The detailed process of this message being carried out the processing of Session Timers agreement is:

If the value of Session-Expires header field is less than the value of local Min_SE header field, when in message, having the Min_SE header field, the value of Min_SE header field in the message increased to equate with the value of local Min_SE header field and as the value of Session-Expires header field, when in message, not having the Min_SE header field, in request message, insert the Min_SE header field, its value is the value of local Min_SE header field, and will be worth the value as Session-Expires.

If the value of Session-Expires header field is not less than the value of local Min_SE header field, then processing method is same as the prior art.

Request message is set up in session after the UAC end of B2BUA Unit 1 is handled according to the UAS end, in this message, insert the supported:timer header field, and the parameter refresher in the Session-Expires header field is set to refersher=uac, and request message is set up in the session that structure makes new advances.

Session after step 502, B2BUA Unit 1 will be handled is set up request message and is sent to the PROXY unit.

Step 503, PROXY unit are set up request message with the session of receiving and are sent to AS (B2BUA 2) unit.

Step 504, B2BUA Unit 2 receive that session sets up request message, and the UAS end of B2BUA Unit 2 is the value of Session-Expires header field and the value of local Min_SE header field relatively.If the value of Session-Expires header field is little, then to B2BUA Unit 1 reply show response that session updates is too short at interval and in response with on the value of local Min_SE header field, B2BUA 1 is received and is replied the value that the value of Session-Expires header field is made after the response into the Min_SE header field, sends to B2BUA Unit 2.

The new request message of request message structure is set up in session after the UAC end of B2BUA Unit 2 is handled according to the UAS end.

Session after step 505, B2BUA Unit 2 will be handled is set up request message and is sent to terminal called.

Step 506, terminal called send 200 response messages of representing successfully to B2BUA Unit 2.

200 response messages are received in step 507, B2BUA Unit 2, and the UAC end of B2BUA Unit 2 does not start session timeout release timer and session updates timer according to the value and the refresher parameter of Session-Expires header field in the response message.

The UAS end of B2BUA Unit 2 starts the session timeout release timer according to the value of Session-Expires header field, does not start the session updates timer.

Step 508, B2BUA Unit 2 send to the PROXY unit with 200 response messages that terminal called sends.

200 response messages that step 509, PROXY unit will be received send to AS (B2BUA Unit 1).

200 response messages are received in step 510, B2BUA Unit 1, and the UAC end of B2BUA Unit 1 starts session timeout release timer and session updates timer according to the value and the refresher parameter of Session-Expires header field in the response message.

The UAS end of B2BUA Unit 1 starts session timeout release timer and session updates timer according to the value of Session-Expires header field.

The UAS end of B2BUA Unit 1 inserts the supported:timer header field in 200 response messages, and the parameter refresher in the Session-Expires header field is set to refersher=uas.

Step 511, B2BUA Unit 1 send to calling terminal with 200 response messages.After calling terminal was received 200 response messages, session was successfully set up, and Session Timers agreement is also consulted success simultaneously.

Step 512, the parameter refresher=uas that determines when consulting, the session updates timer of B2BUA 1 unit UAS end has been crossed (SessionExpires/2) second notice B2BUA Unit 1 and has been sent the session updates request to calling terminal.

Step 513, calling terminal are received the session updates request, reply 200 response messages to B2BUA 1.

200 response messages are received in step 514, B2BUA Unit 1, whether are in active state according to furbisher's rule judgment session.If session is in active state, then session timeout release timer and session updates timer are refreshed, by the time send the session updates request to calling terminal next (SessionExpires/2) second again, and up to the whole session normal termination, Session Timers protects termination; If be in inactive state, then initiatively send END instruction, and discharge the resource of distributing from as this session, finish to connect.

Step 515, the parameter refresher=uac that determines when consulting, the session updates timer of B2BUA 1 unit UAC end has been crossed (SessionExpires/2) second notice B2BUA Unit 1 and has been sent the session updates request to the PROXY unit.

Step 516, PROXY unit send to AS (B2BUA Unit 2) with the session updates request of receiving.

Step 517, B2BUA Unit 2 are received in the session updates request judgement message and are contained the supported:timer header field, message is carried out relevant treatment and this message is sent to terminal called.

B2BUA Unit 2 are to being the same in the relevant treatment of session updates message and the prior art.

Step 518, terminal called receive that the session updates request replys 200 response messages to B2BUA Unit 2.

200 response messages are received in step 519, B2BUA Unit 2, whether are in active state according to the rule judgment session of acting server.If session is in active state, then the session timeout release timer is refreshed; If be in inactive state, then directly discharge the resource of distributing from as this session, finish to connect.

200 response messages that step 520, B2BUA Unit 2 will be received send to the PROXY unit.

200 response messages that step 521, PROXY unit will be received send to AS (B2BUA Unit 1).

The UAC of step 522, B2BUA Unit 1 end is received 200 response messages, whether is in active state according to furbisher's rule judgment session.If session is in active state, then session timeout release timer and session updates timer are carried out refresh operation, by the time send the session updates request to the PROXY unit next (Session Expires/2) second again, and up to the whole session normal termination, Session Timers protects termination; If be in inactive state, then initiatively send to session release request to calling terminal and PROXY unit, and discharge from resource as this session distribution, finish to connect, PROXY receives the unit and discharges after the request from the resource of distributing as this session and this request is sent to B2BUA Unit 2 that B2BUA Unit 2 discharge the resource of distributing from as this session after receiving request.

Shown in Fig. 5 B, present embodiment two realizes that the handling process of resource release is as follows:

The present embodiment furbisher is a terminal called, by terminal called initiation session update request.

Step 5000, calling terminal send session to B2BUA Unit 1 and set up request message.

Step 5001, B2BUA Unit 1 receive that session sets up request message, and the UAS end of B2BUA Unit 1 checks in the message whether be with the supported:timer header field.

If session is set up the supported:timer header field is arranged in the request message, then jump out this flow process, otherwise this message is carried out the processing of Session Timers agreement.

The step of carrying out the processing of Session Timers agreement comprises:

Request message is set up in session after the UAC end of B2BUA Unit 1 is handled according to the UAS end, inserts the supported:timer header field in this message, and request message is set up in the session that structure makes new advances.

Session after step 5002, B2BUA Unit 1 will be handled is set up request message and is sent to the PROXY unit.

Step 5003, PROXY unit are set up request message with the session of receiving and are sent to AS (B2BUA Unit 2).

Step 5004, B2BUA Unit 2 receive that session sets up request message, and the UAS end of B2BUA Unit 2 is the value of Session-Expires header field and the value of local Min_SE header field relatively.If the value of Session-Expires header field is little, then to B2BUA Unit 1 reply show response that session updates is too short at interval and in response with on the value of local Min_SE header field, B2BUA 1 is received and is replied the value that the value of Session-Expires header field is made after the response into the Min_SE header field, sends to B2BUA Unit 2.

Session after the UAC end of B2BUA Unit 2 is handled according to the UAS end is set up the new session of request message structure and is set up request message.

Session after step 5005, B2BUA Unit 2 will be handled is set up request message and is sent to terminal called.

Step 5006, terminal called send 200 response messages of representing successfully to B2BUA Unit 2, and insert the supported:timer header field in response message, and the parameter refresher in the Session-Expires header field is set to refresher=uas.

200 response messages are received in step 5007, B2BUA Unit 2, and the UAC end of B2BUA Unit 2 starts the session timeout release timer, not the session updates timer according to the value and the refresher parameter of Session-Expires header field in the response message.

The UAS end of B2BUA Unit 2 does not start session timeout release timer and session updates timer according to the value of Session-Expires header field.

Step 5008, B2BUA Unit 2 send to the PROXY unit with 200 response messages that terminal called sends.

200 response messages that step 5009, PROXY unit will be received send to AS (B2BUA Unit 1).

200 response messages are received in step 5010, B2BUA Unit 1, and the UAC end of B2BUA Unit 1 starts the session timeout release timer according to the value and the refresher parameter of Session-Expires header field in the response message, does not start the session updates timer.

The UAS end of B2BUA Unit 1 does not start session timeout release timer and session updates timer according to the value of Session-Expires header field.

Step 5011, B2BUA Unit 1 send to calling terminal with 200 response messages.After calling terminal was received 200 response messages, session was successfully set up, and Session Timers agreement is also consulted success simultaneously.

Step 5012, the parameter refresher=uas that consults to set according to the furbisher, the session updates timer of terminal called have crossed (SessionExpires/2) second notice terminal called and have sent the session updates request to B2BUA Unit 2.

Step 5013, B2BUA Unit 2 are received and are judged in the message after the session updates request and contain the support:timer header field, message is carried out relevant treatment and this message is sent to the PROXY unit.

B2BUA Unit 2 are to being the same in the relevant treatment of session updates request and the prior art.

Step 5014, PROXY unit send to AS (B2BUA Unit 1) with the session updates request of receiving.

Step 5015, B2BUA Unit 1 are received and are judged in the message after the session updates request and contain the support:timer header field, message is carried out relevant treatment and this message is sent to calling terminal.

B2BUA Unit 1 is to being the same in the relevant treatment of session updates request and the prior art.

Step 5016, calling terminal receive that session updates message replys 200 response messages to B2BUA Unit 1.

200 response messages are received in step 5017, B2BUA Unit 1, whether are in active state according to the rule judgment session of acting server.If session is in active state, then the session timeout release timer is refreshed; If be in inactive state, then directly discharge the resource of distributing from as this session, finish to connect.

200 response messages that step 5018, B2BUA Unit 1 will be received send to the PROXY unit.

200 response messages that step 5019, PROXY unit will be received send to AS (B2BUA Unit 2).

200 response messages are received in step 5020, B2BUA Unit 2, whether are in active state according to the rule judgment session of acting server.If session is in active state, then the session timeout release timer is refreshed; If be in inactive state, then directly discharge the resource of distributing from as this session, finish to connect.

200 response messages that step 5021, B2BUA Unit 2 will be received send to terminal called.

Terminal called receives whether the rule judgment session according to the furbisher is in active state behind 200 response messages.If session is in active state, then the session timeout release timer is refreshed, Session Timers finishes session updates, by the time send the session updates request to B2BUA Unit 2 again after (SessionExpires/2) second, up to the whole session normal termination, Session Timers protects termination; If be in inactive state, then initiatively send to session and discharge request to B2BUA Unit 2, and discharge from resource as this session distribution, finish to connect, B2BUA Unit 2 are received and are discharged after the request from the resource of distributing as this session and this request is sent to the PROXY unit, PROXY receives the unit and discharges after the request from the resource of distributing as this session and this request is sent to B2BUA Unit 1 that B2BUA Unit 1 discharges the resource of distributing from as this session after receiving request.

As shown in Figure 6, the handling process of present embodiment three is as follows:

Step 600, calling terminal send session to B2BUA 1 and set up request message.

Step 601, B2BUA Unit 1 receive that session sets up request message, and the UAS end of B2BUA Unit 1 checks in the message whether be with the supported:timer header field.

Do not have the supported:timer header field in the request message if session is set up, then jump out this flow process, otherwise this message is carried out the processing of Session Timers agreement.

The step of carrying out the processing of Session Timers agreement comprises:

If the value of Session-Expires header field is less than the value of local Min_SE header field, then to calling terminal reply show response that session updates is too short at interval and in response with on the value of the local Min_SE header field that allows, calling terminal is received and is replied the value that the value of Session-Expires header field is made after the response into the Min_SE header field, sends to B2BUA Unit 1 again.

Session after the UAC end of B2BUA Unit 1 is handled according to the UAS end is set up the new session of request message structure and is set up request message.

Session after step 602, B2BUA Unit 1 will be handled is set up request message and is sent to the PROXY unit.

Step 603, PROXY unit are set up request message with the session of receiving and are sent to AS (B2BUA Unit 2).

Step 604, B2BUA Unit 2 receive that session sets up the value that the UAS end of request message B2BUA Unit 2 is checked the Session-Expires header field.If the value of Session-Expires header field is less than the value of local Min_SE header field, then by B2BUA 1 to calling terminal reply show response that session updates is too short at interval and in response with on the value of the local Min_SE header field that allows, calling terminal is received and is replied the value that the value of Session-Expires header field is made after the response into the Min_SE header field, resends.

Step 605, B2BUA Unit 2 are set up request message with session and are sent to terminal called.

Step 606, terminal called are agreed what the request message of B2BUA Unit 2 transmission sent, send 200 response messages of representing successfully to B2BUA Unit 2.

200 response messages are received in step 607, B2BUA Unit 2, and the UAC end of B2BUA Unit 2 does not start session timeout release timer and session updates timer according to the value and the refresher parameter of Session-Expires header field in the response message.

Step 608, B2BUA Unit 2 send to the PROXY unit with 200 response messages that terminal called sends.

Step 609, PROXY unit will receive that 200 response messages send to AS (B2BUA Unit 1).

200 response messages are received in step 610, B2BUA Unit 1, and the UAC end of B2BUA Unit 1 does not start session timeout release timer and session updates timer according to the value and the refresher parameter of Session-Expires header field in the response message.

The UAS end of B2BUA Unit 1 starts the session timeout release timer according to the value of Session-Expires header field, does not start the session updates timer.

Step 611, B2BUA Unit 1 send to calling terminal with 200 response messages that the PROXY unit sends.After calling terminal was received 200 response messages, session was successfully set up, and Session Timers also consults success simultaneously.

Step 612, according to the parameter refresher=uac that session negotiation is set, the session updates timer of calling terminal has been crossed (SessionExpires/2) second notice calling terminal and has been sent the session updates request to B2BUA Unit 1.

Step 613, B2BUA Unit 1 are received and are judged in the message after the session updates request and contain the support:timer header field, message is carried out relevant treatment and this message is sent to the PROXY unit.

Step 614, PROXY unit send to AS (B2BUA Unit 2) with the session updates request of receiving.

Step 615, B2BUA Unit 2 are received and are judged in the message after the session updates request and contain the support:timer header field, message is carried out relevant treatment and this message is sent to terminal called.

Step 616, terminal called receive that session updates message replys 200 response messages to B2BUA Unit 2.

200 response messages are received in step 617, B2BUA Unit 2, whether are in active state according to the rule judgment session of acting server.If session is in active state, then the session timeout release timer is refreshed; If be in inactive state, then directly discharge the resource of distributing from as this session, finish to connect.

200 response messages that step 618, B2BUA Unit 2 will be received send to the PROXY unit.

200 response messages that step 619, PROXY unit will be received send to AS (B2BUA Unit 1).

200 response messages are received in step 620, B2BUA Unit 1, whether are in active state according to the rule judgment session of acting server.If session is in active state, then the session timeout release timer is refreshed; If be in inactive state, then directly discharge the resource of distributing from as this session, finish to connect.

200 response messages that step 621, B2BUA Unit 1 will be received send to calling terminal.

Calling terminal receives whether the rule judgment session according to the furbisher is in active state behind 200 response messages.If session is in active state, then the session timeout release timer is refreshed, Session Timers finishes session updates, by the time send the session updates request to B2BUA Unit 1 again after (SessionExpires/2) second, up to the whole session normal termination, Session Timers protects termination; If be in inactive state, then initiatively send to session and discharge request to B2BUA Unit 1, and discharge from resource as this session distribution, finish to connect, B2BUA Unit 1 is received and is discharged after the request from the resource of distributing as this session and this request is sent to the PROXY unit, PROXY receives the unit and discharges after the request from the resource of distributing as this session and this request is sent to B2BUA Unit 2 that B2BUA Unit 2 discharge the resource of distributing from as this session after receiving request.

Embodiment shown in Figure 6 sends the session updates request by calling terminal, the parameter of refresher is uac when consulting, each B2BUA unit can not start session updates request timer, after receiving the session updates request, can not generate new session updates request, thereby avoided transmitting unnecessary session updates request among Figure 1A and Figure 1B, solved the problem of message collision among Figure 1B simultaneously.

Embodiment shown in Figure 7 sends the session updates request by terminal called, and the parameter of refresher is uas when consulting, and just on the direction that sends a request message variation has taken place with Fig. 6.

As shown in Figure 7, the handling process of present embodiment four is as follows:

Step 700 to step 711 and step 600 to the parameter refresher=uas of step 611 except in session negotiation, setting, send the session updates request by terminal called, the UAS end of B2BUA Unit 1 and B2BUA Unit 2 starts the session timeout release timer, and other steps are identical.

Step 712, according to the parameter refresher=uas that session negotiation is set, the session updates timer of terminal called has been crossed (SessionExpires/2) second notice terminal called and has been sent the session updates request to B2BUA Unit 2.

Step 713, B2BUA Unit 2 are received and are judged in the message after the session updates request and contain the support:timer header field, message is carried out relevant treatment and this message is sent to the PROXY unit.

Step 714, PROXY unit send to AS (B2BUA Unit 1) with the session updates request of receiving.

Step 715, B2BUA Unit 1 are received and are judged in the message after the session updates request and contain the support:timer header field, message is carried out relevant treatment and this message is sent to calling terminal.

Step 716, calling terminal receive that session updates message replys 200 response messages to B2BUA Unit 1.

200 response messages are received in step 717, B2BUA Unit 1, whether are in active state according to the rule judgment session of acting server.If session is in active state, then the session timeout release timer is refreshed; If be in inactive state, then directly discharge the resource of distributing from as this session, finish to connect.

200 response messages that step 718, B2BUA Unit 1 will be received send to the PROXY unit.

200 response messages that step 719, PROXY unit will be received send to AS (B2BUA Unit 2).

200 response messages are received in step 720, B2BUA Unit 2, whether are in active state according to the rule judgment session of acting server.If session is in active state, then the session timeout release timer is refreshed; If be in inactive state, then directly discharge the resource of distributing from as this session, finish to connect.

200 response messages that step 721, B2BUA Unit 2 will be received send to terminal called.

Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims

1. method that realizes that resource discharges is characterized in that this method comprises:

2. method according to claim 1 is characterized in that, sets up in the process in session, and this method further comprises:

Carry out furbisher's negotiation between the node device, determine that a node device is the furbisher;

After session is set up, by consulting to be defined as of the network node transmission session updates request of furbisher's node device to other.

3. method according to claim 2 is characterized in that, after session was set up, this method also comprised:

After each node device is received the session updates request, judge the Supported header field that whether contains band timer label in the session updates request, if then only send the session updates request to the next node equipment of session institute approach according to the session updates request of receiving.

4. method according to claim 2 is characterized in that, carries out furbisher's negotiation between the described node device, determines that a node device comprises for furbisher's step:

After A12, terminal called receive that request message is set up in this session, determine that self is not the furbisher, then returns to this B2BUA by node device and self does not set up response message for furbisher's session;

After A13, this B2BUA unit receive that response message is set up in this session, determine certainly as the furbisher, then add furbisher's parameter in the Session-Expires header field of setting up to the session of calling terminal answer in the response message, refresher is set to subscriber proxy server end uas.

5. method according to claim 2 is characterized in that, carries out furbisher's negotiation between the described node device, determines that a node device comprises for furbisher's step:

6. method according to claim 5 is characterized in that, self does not set up response message for furbisher's session and sets up response message for the session that does not contain the Supported header field of being with the timer label described in the steps A 22;

Self not setting up response message for furbisher's session described in the steps A 22 is that response message is set up in the session that contains the Supported header field of band timer label, and wherein the refresher of Session-Expires header field is uas.

7. a system that realizes that resource discharges is characterized in that this system comprises: one or more B2BUA unit;

Each B2BUA unit, be used to receive set up request message from the session of a last node device after, judge that this session sets up the Supported header field that whether carries the timer label in the request message, if contain, request message is set up in this session to be transmitted to next node device, otherwise, set up the Supported header field that adds band timer label in the request message in session, request message is set up in this session transmitted to next node device; After session is set up,, discharge the resource of distributing from as this session if determine that this session is in inactive state.

8. system according to claim 7, it is characterized in that, described B2BUA unit is further used for: after session is set up, if receive the session updates request, whether judge in the session updates request Supported header field with the timer label, if then only send the session updates request to next network node of session institute approach according to the session updates request of receiving.

9. system according to claim 7 is characterized in that, described B2BUA unit comprises:

10. system according to claim 8 is characterized in that, described B2BUA unit also further comprises:

11. a back-to-back user agent device is characterized in that, this device comprises:

12. device according to claim 11 is characterized in that, described B2BUA device further comprises: