CN105306453B

CN105306453B - Evaluating initial filter criteria

Info

Publication number: CN105306453B
Application number: CN201510639862.3A
Authority: CN
Inventors: H.普尔兹比茨; A.海德马克; T.福斯曼
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2007-01-16
Filing date: 2007-01-16
Publication date: 2020-04-14
Anticipated expiration: 2027-01-16
Also published as: CN105306453A

Abstract

The present application relates to "evaluating initial filter criteria". A method of evaluating initial filter criteria at a terminating call session control function in an IP multimedia subsystem network. A session initiation protocol including a destination uniform resource identifier is received. As a result of the initial filter criteria being applied to the message, the message is sent to the application server and evaluation of further initial filter criteria is suspended. The returned message is received from the application server and it is determined whether the uniform resource identifier has been changed by the application server. If the uniform resource identifier has been changed by the application server, it is determined whether to resume evaluation of the initial filter criteria, and if the uniform resource identifier has not been changed by the application server, the evaluation of the initial filter criteria is resumed.

Description

Evaluating initial filter criteria

The filing date of the parent case of the divisional application is 1 month and 16 days 2007, the application number is 200780050027.X, and the invention name is 'evaluation initial filtration standard'.

Technical Field

The present invention relates to a method and apparatus for evaluating (evaluate) initial filter criteria in an IP multimedia subsystem network.

Background

IP multimedia (IPMM) is an example of a service that provides a dynamic combination of voice, video, messaging, data, etc. in the same session. By increasing the number of basic applications and the media that can be combined, the number of services offered to the end user will increase and the interpersonal communication experience will be enriched. This will lead to a new generation of personalised, rich multimedia communication services, such as peer-to-peer multimedia communication, IPTV, etc.

These services can be based on the IP Multimedia Subsystem (IMS) architecture, which is a technology defined by the third generation partnership project (3GPP) to provide IP multimedia services over mobile communication networks (3GPP TS 22.228, TS23.228, TS 24.229, TS 29.228, TS 29.229, TS 29.328 and TS 29.239 releases 5-7).

The IMS makes use of the Session Initiation Protocol (SIP) to set up and control calls or sessions between user terminals (or user terminals and application servers). The Session Description Protocol (SDP), carried by SIP signalling, is used to describe and negotiate the media components of the session. Fig. 1 schematically illustrates how IMS adapts to the mobile network architecture in the case of a 3GPP PS access domain.

Services can be provided to users via the IMS network using an Application Server (AS). When a user registers with the IMS network, service provisioning is triggered using one or more Initial Filter Criteria (IFCs) that are stored in the user profile and downloaded to the user' S serving call session control function (S-SCSF). The IFC consists of trigger points and addresses of one or more ASs. The trigger point describes the condition: wherein the condition has to be checked to find out whether the indicated AS should be contacted.

As shown in fig. 2, when the S-CSCF receives the message, it checks the stored IFCs. If the incoming (incomming) message meets the condition of the trigger point in the IFC, the S-CSCF passes the message to the AS indicated by the IFC. Once the AS has processed the message, the message is returned to the S-CSCF and the next IFC is checked. The IFCs can be given a priority number so that if more than one IFC associated with a user is stored at the S-CSCF, the IFCs are checked in order of priority.

The interface between the S-CSCF and the AS is the IMS Service Control (ISC) interface, which uses SIP signaling to communicate between the AS and the S-CSCF.

The 3GPP IMS specification TS 24.229 v7.5.1 provides a mechanism to allow an AS to perform a change of SIP request target by modifying the request-URI (uniform resource indicator) contained in the message. When a message is returned from the AS to the S-CSCF, the S-CSCF detects the change in the request-URI and interrupts the check for Initial Filter Criteria (IFC) evaluation, AS shown in fig. 3. The message is passed directly to outgoing (outsourcing) request processing and no lower priority IFCs are checked, which prevents calls to other ASs.

The original motivation for this mechanism comes from the requirement of a call forwarding service that allows the AS to change the destination address of the SIP request. At this point, it cannot be imagined that any other service would require: the AS should change the request-URI of the SIP request. Nevertheless, several cases are to be considered, which may require the AS to change the request-URI of the SIP request, but which should not interrupt the IFC evaluation procedure at the S-CSCF. Examples of such cases include the following:

1. a user with an IMS public user Identity (IMPU) may use more than one UE. The AS receives requests addressed to (address to) the user's IMPU and selects a SIP User Agent (UA) AS an endpoint, typically the UA is the user's terminal addressed by a Globally Routable UA URI (GRUU) or Contact (Contact). When an AS wants to initiate a terminating session with a User Equipment (UE), a problem may arise if IMPUs assigned to the UE are shared by other UEs. To fully control which UE the terminating session request is sent to, the AS must change the target of the request from IMPU to the address of the selected endpoint.

2.A similar problem occurs when the AS changes the IMPU of the user. This may be required, for example, when the AS receives an IMPU with a TEL URI and sends another one with a SIP URI (or vice versa).

3. The AS may be required to change the request-URI of the incoming request from the SIP URI to the Tel URI. This change is required when only a telephone number can be used to contact a device connected to the network using the Public Switched Telephone Network (PSTN).

In both of the above cases it may be desirable for the S-CSCF to continue the IFC evaluation after the AS has changed the request-URI in the message. This does not change the target user, but only addresses the same user's endpoint or a subset of the user's endpoints using the alternate address. This is different from the "call forwarding" scenario, where the actual target user is changed, and is the main reason that existing mechanisms to interrupt IFC evaluation are not suitable for these cases in case of address change.

Disclosure of Invention

According to a first aspect of the present invention there is provided a method of evaluating initial filter criteria at a terminating call session control function in an IP multimedia subsystem network, the method comprising:

receiving a session initiation protocol message, the session initiation protocol message including a destination uniform resource identifier;

sending the message to the application server as a result of applying the initial filter criteria to the message, and suspending (suspend) evaluation of further initial filter criteria;

receiving a message returned from the application server;

determining whether the uniform resource identifier has been changed by the application server;

if the uniform resource identifier has been changed by the application server, it is determined whether to resume (resume) the evaluation of the initial filter criteria, and if the uniform resource identifier has not been changed by the application server, the evaluation of the initial filter criteria is resumed.

In this way, a decision is made as to whether to proceed with the IFC evaluation even if the destination uniform resource identifier has been changed.

The step of determining whether to resume evaluating the initial filter criteria may include determining whether the initial filter criteria has an associated target change override indicator (override indicator), and if so, resuming evaluating the initial filter criteria. In this case, the target change override indicator is typically associated with the initial filter criteria and stored as part of the user profile.

Alternatively, the step of determining whether to resume evaluating the initial filter criteria may comprise determining whether a message received from the application server contains a target change override indicator, and if so, resuming evaluating the initial filter criteria. This allows the application server to decide whether to include a target change override indicator.

In an alternative method, the step of determining whether to resume evaluating the initial filter criteria may comprise determining whether a destination uniform resource identifier contained in the message received from the application server relates to an IP multimedia subsystem public user identity belonging to the same user as the IP multimedia subsystem public user identity contained in the received message, and if so, continuing with resuming evaluating the initial filter criteria.

According to a second aspect of the present invention there is provided a terminating call session control function for use in an IP multimedia subsystem network, the call session control function comprising:

means for receiving a session initiation protocol message, the message comprising a destination uniform resource identifier;

means for evaluating initial filter criteria to be applied to the message;

a transmitter for sending a message to an application server;

means for receiving a message returned from the application server;

means for determining whether the application server has changed the destination uniform resource identifier; and

means for determining whether to continue evaluating the initial filter criteria or whether to stop evaluating the initial filter criteria if the application server has changed the destination uniform resource identifier.

According to a third aspect of the present invention, there is provided an application server comprising:

a receiver for receiving a message, the message comprising a destination uniform resource identifier;

means for modifying a uniform resource identifier of a message;

means for including a destination address ignore indicator in the message; and

a transmitter for sending a message to a call session control function.

According to a fourth aspect of the present invention there is provided a method of processing a session initiation protocol message at a terminating call session control function in an IP multimedia subsystem network, the method comprising:

applying at least one initial filter criterion to the message;

sending the message to the application server as a result of the initial filter criteria being applied;

receiving a message returned from the application server;

determining whether the returned message includes a new target uniform resource identifier;

if the returned message includes the new target uniform resource identifier, the destination uniform resource identifier is replaced with the new target uniform resource identifier.

The method allows all initial filter criteria to be evaluated before changing the destination uniform resource identifier, even where the application server invoked by the first initial filter criteria of the plurality of initial filter criteria wishes to change the destination uniform resource identifier.

According to a fifth aspect of the present invention there is provided a call session control function for use in an IP multimedia subsystem network, the call session control function comprising:

means for applying initial filter criteria to the message;

a transmitter for sending a message to an application server;

means for receiving a message returned from the application server;

means for determining whether a body of the returned message includes a new target uniform resource identifier; and

means for replacing the destination uniform resource identifier in the message with the new target uniform resource identifier.

Drawings

Figure 1 schematically illustrates how IMS adapts to a mobile network architecture in the case of a 3GPP PS access domain;

FIG. 2 schematically illustrates invocation of an application server by the S-CSCF in response to initial filtering criteria being met;

FIG. 3 schematically illustrates invocation of an application server by the S-CSCF in response to the initial filter criteria being met, wherein the application server changes the target URI;

figure 4 schematically illustrates the invocation of an application server by the S-CSCF according to the present invention;

figure 5 shows a signalling sequence when the target change override indication is associated with an IFC in a user profile;

FIG. 6 shows a signaling sequence when the application server signals a target change override indication;

figure 7 shows a signalling sequence when the application server signals a new target; and

figure 8 shows the signalling sequence in the case where target change override logic is used in the S-CSCF.

Detailed Description

The S-CSCF can determine if the AS has changed the request-URI. If it is determined that the request-URI has been changed, the S-CSCF decides whether to continue the evaluation of the Initial Filter Criteria (IFC). This is illustrated in fig. 4.A first initial filter criterion IFC-1 is applied to the incoming message at the S-CSCF. The message is delivered to application server AS-1 indicated in IFC 1. After which the message is returned from AS-1 to the S-CSCF. The S-CSCF determines whether the request-URI has been changed. If not, the next initial filter criteria IFC-2 is applied to the message. If the S-CSCF determines that the request-URI has been changed, the S-CSCF determines whether to resume IFC evaluation. If not, the message is passed directly to egress request processing in the S-CSCF. Alternatively, if the S-CSCF determines that the IFC evaluation should be resumed, a message with a modified request-URI is passed to the IFC2 for evaluation. The process continues for each IFC.

Note that in fig. 4, the check to determine whether the request-URI has been changed is shown to occur before the check to determine whether to resume IFC evaluation or to pass the message directly to outgoing request processing in the S-CSCF. The order of these two checks can be reversed.

There are several different ways in which the S-CSCF determines whether to continue the IFC evaluation once the request-URI of the message has been changed. The following are three possible ways:

1. when the user registers with the network, a target change override indication is included as part of the user profile stored in the HSS and downloaded to the S-CSCF. The target change override indication is associated with a particular IFC. When the S-CSCF receives a SIP request with a changed target returned by an AS invoked by an IFC with a target change override indication, the S-CSCF will not interrupt the IFC evaluation and continue the process, although the target has changed.

2. The target change override indication is introduced AS part of the signalling on the ISC interface between the S-CSCF and the AS. The AS that changes the target of the request may also include a target change override indication in the SIP request sent to the S-CSCF. The target change override indication may be located in any suitable part of the SIP message, including the message header or the message body. The S-CSCF reads the target change override indication in the SIP message and resumes IFC evaluation. There are other alternative methods with which the AS may signal a target change and ignore indication to the S-CSCF via the ISC, AS follows:

as change request-URI and including in the SIP request an explicit destination address change override indication;

the as keeps the request-URI unchanged, but sends the new destination address in the SIP request (e.g. in the SIP header).

3. New logic is introduced in the S-CSCF to analyze the changed destination address of the request to determine whether to continue or stop the IFC evaluation. The logic determines whether the changed target is another IMPU belonging to the user, or whether the target is derived from an IMPU belonging to the user, or whether it is a SIP User Agent (UA) currently registered for the user. If either of these conditions is met, the S-CSCF resumes IFC evaluation, otherwise the SIP message is passed to outgoing request processing.

These three examples are now described in more detail:

1. a target change override indication associated with the IFC in the user profile.

The signaling sequence for this embodiment is illustrated in fig. 5.

1.1. The target change override indication is included as part of the user profile in the HSS. The target change ignore indication is associated with an IFC directed to a particular AS. When the S-CSCF is allocated to a user (typically at the time of registration of the user or when a termination request is received for an unregistered user with terminating service), a target change override indication is downloaded to the S-CSCF as part of the user profile. Thus, the target change override indication is a supplement to the existing user profile stored in the HSS and cached by the S-CSCF.

1.2. When the S-CSCF receives a terminating initial SIP request for a served user, it performs an existing IFC evaluation procedure by matching the received request with the stored IFCs in their predetermined priority order. If the request matches an IFC, the evaluation is aborted and the request is forwarded to the AS to which the matching IFC is directed.

1.3. When the AS receives the SIP request and decides to change the destination of the request, it includes the new destination in the request-URI of the SIP request and returns the SIP request to the S-CSCF.

1.4. When the S-CSCF receives a SIP request returned by the AS, it checks whether the request target has been changed and whether a target change override indication is associated with the IFC that triggers the message to be sent to the AS. The S-CSCF checks whether the request target has been changed by comparing the request-URI of the SIP message sent to the AS with the request-URI of the SIP message received from the AS. The following actions occur:

1.4.a. if the request target has not been changed, resuming IFC evaluation according to step 1.5 below;

1.4.b. if the AS target change ignore indication pointed to by the IFC triggering the call is set, then resume IFC evaluation AS per step 1.5 below;

1.4.c. if the request target has been changed and the target change override indication by the AS to which the IFC triggering the invocation is directed is not set, then the IFC evaluation is not resumed and the message is passed to outgoing request processing;

1.5. in case the S-CSCF restores the IFC evaluation AS required by steps 4a and 4b above, the S-CSCF restores the IFC evaluation by matching the SIP request received from the AS with the stored IFCs (from the next IFC) in a predetermined priority order. If the request matches an IFC, the evaluation is aborted and the request is forwarded to the AS to which the matching IFC is directed. The process continues from step 3.

AS signaled target change override indication

The signaling order for this embodiment is illustrated in fig. 6 and described as follows:

2a.1. when the S-CSCF receives a terminating initial SIP request for a served user, it performs an existing IFC evaluation procedure by matching the received request with stored IFCs in a predetermined priority order of the user. If the SIP request matches an IFC, the evaluation is aborted and the request is forwarded to the AS indicated by the matching IFC.

2a.2. when the AS receives the SIP request and decides to change the target of the request, it forwards the SIP request back to the S-CSCF (with the new target in the request-URI of the SIP request) and it also includes a new target change ignore indication in the SIP request to instruct the S-CSCF to proceed with the IFC evaluation.

2a.3. when the S-CSCF receives a SIP request returned by the AS, it determines whether the request target has been changed and whether a target change override indication is included in the received request. The S-CSCF removes all received target change override indications from the request either before further processing in step 2.4 or before performing outgoing request processing. As a result of step 2.3, the following actions may occur:

2a.3.a. if the request target has not been changed, resuming IFC evaluation according to step 2a.4 below;

2a.3.b. if the request target has been changed and a target change ignore indication is received in the request from the AS indicating "ignore", resuming IFC evaluation according to step 2a.4 below;

2a.3.c. if the request target has been changed but the SIP message received from the AS does not contain a target change override indication, then the IFC evaluation is not resumed and the message is forwarded to outgoing request processing.

2a.4. if IFC evaluation is resumed, the S-CSCF resumes the existing IFC evaluation procedure by matching the received request with the stored IFCs (from the next IFC) in a predetermined priority order. If the request matches an IFC, the evaluation is aborted and the request is forwarded to the AS to which the matching IFC is directed. The process continues from step 2.2.

New target signalled by AS

The signaling order for this embodiment is illustrated in fig. 7 and described as follows:

2b.1. when the S-CSCF receives a terminating initial SIP request for a served user, it performs an existing IFC evaluation procedure by matching the received request with the stored IFCs in their predetermined priority order. If the request matches an IFC, the evaluation is aborted and the request is forwarded to the AS to which the matching IFC is directed.

2b.2. when the AS receives the SIP request and decides to change the target of the request, it forwards the SIP request back to the S-CSCF but does not change the request-URI of the request. Instead, it adds a new target to the SIP request. The new target may be included in the new header or, alternatively, in the message body.

2b.3. the as returns the SIP request to the S-CSCF, with the request-URI unchanged. Thus, the S-CSCF resumes IFC evaluation according to the existing procedure by matching the received request with the stored IFCs (from the next IFC) in a predetermined priority order. If the request matches an IFC, the evaluation is aborted and the request is forwarded to the AS to which the matching IFC is directed. The process continues from step 3.2.

2b.4. at the end of the evaluation procedure and before performing outgoing request processing, the S-CSCF checks if a new target is present in the SIP request. If a new target exists, the S-CSCF will place it in the request-URI of the request and remove it from the request. Thereafter, it proceeds with normal outgoing request processing on a new target basis.

New target change override logic in S-CSCF

The signaling order for this embodiment is illustrated in fig. 8 and described as follows:

3.1. when the S-CSCF receives a terminating initial SIP request for a served user, it performs an existing IFC evaluation procedure by matching the received request with the stored IFCs in their predetermined priority order. If the request matches an IFC, the evaluation is aborted and the request is forwarded to the AS to which the matching IFC is directed.

3.2. the AS receives the SIP request and decides the target of the change request. The request message is forwarded back to the S-CSCF with the new destination in the request-URI of the SIP request.

3.3. When the S-CSCF receives a SIP request returned by the AS, it determines whether the AS has changed the requested target and, if so, the S-CSCF applies logic to determine whether to ignore the target change. The logic is based on the S-CSCF knowledge of all identities belonging to a user, including the GRUU of the user in addition to the contact address currently registered by the served user. The new logic will determine whether the changed target belongs to a served user.

3.3.a. if the request target has not been changed, resuming IFC evaluation according to step 3.4;

3.3.b. if the request target has been changed and the S-CSCF determines that the new target belongs to a served user, then the IFC evaluation is resumed according to step 3.4;

3.3.c. if the request target has been changed and the S-CSCF determines that the new target does not belong to a served user, then the IFC evaluation is not resumed and a message is sent for outgoing request processing;

3.4. in case the S-CSCF determines that the IFC evaluation should be resumed, the S-CSCF resumes the existing IFC evaluation procedure by matching the received request with the stored IFCs (from the next IFC) in a predetermined priority order. If the request matches an IFC, the evaluation is aborted and the request is forwarded to the AS to which the matching IFC is directed. The process continues from step 3.2.

It will be appreciated by those skilled in the art that various modifications could be made to the above-described embodiments without departing from the scope of the invention.

Claims

1. A method of evaluating initial filter criteria at a terminating call session control function in an IP multimedia subsystem network, the method comprising:

receiving a session initiation protocol message, the session initiation protocol message including a request-uniform resource identifier;

sending the message to an application server as a result of applying initial filter criteria to the message, and suspending evaluation of further initial filter criteria;

receiving a message returned from the application server;

determining whether to resume evaluation of the initial filter criteria;

determining whether the request-uniform resource identifier has been changed by the application server.

2. The method of claim 1, wherein the step of determining whether to resume evaluating the initial filter criteria comprises determining whether the initial filter criteria has an associated target change override indicator, and if so, resuming evaluating the initial filter criteria.

3. The method of claim 1, wherein the step of determining whether to resume evaluating initial filter criteria comprises determining whether a message received from an application server contains a target change override indicator, and if so, resuming evaluating initial filter criteria.

4. The method of claim 1, wherein the step of determining whether to resume evaluating the initial filter criteria comprises determining whether a request-uniform resource identifier contained in the message received from the application server relates to an IP multimedia subsystem public user identity belonging to the same user as the IP multimedia subsystem public user identity contained in the received message, and if so, continuing with resuming evaluating the initial filter criteria.

5. A terminating call session control function for use in an IP multimedia subsystem network, the terminating call session control function comprising:

means for receiving a session initiation protocol message, the message comprising a request-uniform resource identifier;

means for evaluating initial filter criteria to be applied to the message;

a transmitter for sending the message to an application server;

means for receiving a message returned from the application server;

means for determining whether to continue evaluating the initial filter criteria or whether to stop evaluating the initial filter criteria;

means for determining whether the request-uniform resource identifier has been changed by the application server after the above determination.

6. An application server, comprising:

a receiver for receiving a message, the message comprising a request-uniform resource identifier, and the message being a SIP request;

means for modifying the request-uniform resource identifier of the message;

means for including in the message a destination address ignore indicator that is usable by a call session control function to determine that initial filter criteria evaluation should continue; and

a transmitter for sending a message generated by said modifying said message and including said destination address ignore indicator to said call session control function.

7. A method of processing a session initiation protocol message at a terminating call session control function in an IP multimedia subsystem network, the method comprising:

applying at least one initial filter criterion to the message;

sending the message to an application server as a result of the initial filter criteria being applied;

receiving the message returned from the application server with an unchanged request-uniform resource identifier;

determining whether the returned message includes a new target uniform resource identifier and, if so, replacing the request-uniform resource identifier with the new target uniform resource identifier; and

the evaluation of the initial filter criteria is resumed.

8. A call session control function for use in an IP multimedia subsystem network, the call session control function comprising:

means for applying initial filter criteria to the message;

a transmitter for sending the message to an application server;

means for receiving the message returned from the application server with an unchanged request-uniform resource identifier;

means for resuming evaluation of the initial filter criteria;

means for replacing the request-uniform resource identifier in the message with a new target uniform resource identifier if it is determined that the returned message includes the new target uniform resource identifier prior to the initial filter criteria evaluation.

9. A method of evaluating initial filter criteria at a terminating call session control function in an IP multimedia subsystem network, the method comprising:

receiving a session initiation protocol message, the session initiation protocol message including an initial request-uniform resource identifier;

applying initial filter criteria to the message;

receiving a message returned from the application server;

determining whether the application server has changed the initial request-uniform resource identifier to a changed request-uniform resource identifier;

when the application server has changed the original request-uniform resource identifier:

determining whether to resume evaluation of the initial filter criteria;

upon determining not to resume evaluation of initial filter criteria, passing the returned message directly to outgoing message processing in the terminating call session control function; and

upon determining to resume evaluation of the initial filter criteria, resuming evaluation of the initial filter criteria using the changed request-uniform resource identifier; and

when the initial request-uniform resource identifier is unchanged by the application server, the evaluation of the initial filter criteria is resumed using the initial request-uniform resource identifier.

10. The method of claim 9, wherein the step of determining whether to resume evaluation of initial filter criteria comprises determining whether the initial filter criteria has an associated target change override indicator, and if so, resuming evaluation of initial filter criteria with the changed request-uniform resource identifier.

11. The method of claim 9, wherein the step of determining whether to resume evaluation of initial filter criteria comprises determining whether the returned message contains a target change override indicator, and if so, resuming evaluation of initial filter criteria using the changed request-uniform resource identifier.

12. The method according to claim 9, wherein the step of determining whether to resume evaluation of initial filter criteria comprises determining whether the changed request-uniform resource identifier contained in the returned message relates to an IP multimedia subsystem public user identity belonging to the same user as the IP multimedia subsystem public user identity contained in the received session initiation protocol message, and if so, resuming evaluation of initial filter criteria using the changed request-uniform resource identifier.

13. The method of claim 9, further comprising: replacing the initial request-uniform resource identifier with the changed request-uniform resource identifier received from the application server whenever the application server has changed the initial request-uniform resource identifier after evaluation of initial filter criteria is complete.