METHOD OF SESSION PROCESSING IN AN IMS AND INTERROGATING-CALL STATE CONTROL FUNCTION

• US 20080160996A1
• Filed: 02/29/2008
• Published: 07/03/2008
• Est. Priority Date: 08/31/2005
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: ZHAO, Jianguo, LI, Changlin, WANG, Jing, HE, Xiaoyan, ZHU, Fenqin
• Granted Patent: US 8,295,158 B2
• Time in Patent Office: Days
• US Class Current: 455/433
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]

Abstract

A method of session processing in the Internet Protocol (IP) Multimedia Subsystem (IMS) comprises: Interrogating-Call State Control Function (I-CSCF) accessing the Home Subscriber Server (HSS) to query the registration location of the called user, the I-CSCF sending the Session Initiation Protocol (SIP) request to the Serving-Call State Control Function (S-CSCF) based on the response of the HSS; when the response time of the S-CSCF to the SIP request sent from the I-CSCF has expired, the I-CSCF re-selecting the S-CSCF, and sending the SIP request to the S-CSCF. And an Interrogating-Call State Control Function is provided. According to the present invention, if the S-CSCF returned by the HSS to process the unregistered service of the IMS user does not responded because of the device failure or communication interruption or the like, the I-CSCF can re-select other S-CSCF to process the unregistered service of the IMS user, so as to improve the quality of service and to increase the satisfaction of user.

Claims

1. A session processing method in an Internet Protocol multimedia subsystem, wherein the method comprises:

receiving an initial request for a called user by an Interrogating-Call Session Control Function (I-CSCF) module;

inquiring, by the I-CSCF, a Home Subscriber Server (HSS) about the registration location of the called user;

sending, by the I-CSCF, a Session Initiation Protocol (SIP) request to a Serving-Call Session Control Function (S-CSCF) module according to a response from the HSS; and

reselecting an S-CSCF if receiving no response from the S-CSCF within a prescribed period of time, and sending a SIP request to the reselected S-CSCF, by the I-CSCF.

2. The session processing method in an Internet Protocol multimedia subsystem according to claim 1, wherein the I-CSCF acts as a stateful proxy.

3. The session processing method in an Internet Protocol multimedia subsystem according to claim 1, wherein the process of reselecting an S-CSCF comprises:

obtaining, by the I-CSCF, a set of S-CSCF capabilities required by the called user, selecting an S-CSCF in accordance with the set of S-CSCF capabilities, and sending a SIP request to the selected S-CSCF for processing.

4. The session processing method in an Internet Protocol multimedia subsystem according to claim 3, wherein the process of obtaining, by the I-CSCF, of a set of S-CSCF capabilities required by the called user comprises:

obtaining a set of S-CSCF capabilities required by the called user from HSS by modifying a command Cx-Location-Query or Cx-Select-Pull;

the process of modifying a command Cx-Location-Query comprises adding a user location query type parameter User-Location-Type AVP in the command; and

the process of modifying a command Cx-Select-Pull comprises modifying the IMPI attribute type of the command as being conditional.

5. The session processing method in an Internet Protocol multimedia subsystem according to claim 3, wherein the process of obtaining, by the I-CSCF, of a set of S-CSCF capabilities required by the called user comprises:

receiving the response from the HSS which comprising the set of S-CSCF capabilities by the I-CSCF,

obtaining the set of S-CSCF capabilities from the response.

6. The session processing method in an Internet Protocol multimedia subsystem according to claim 1, further comprising:

receiving an initial request to a called user and inquiring a Home Subscriber Server (HSS) about the registration location of the called user, by an Interrogating-Call Session Control Function (I-CSCF) module;

acting, by the I-CSCF, as a stateful proxy if a response from the HSS comprises an indication that part of identity identifiers are in an unregistered state and none of the identity identifiers is in a registered state (DIAMETER_SOME_ID_UNREGISTERED) or an indication of awaiting processing of an unregistered service (DIAMETER_UNREGISTERED_SERVICE), and sending, by the I-CSCF, a Session Initiation Protocol (SIP) request to a Serving-Call Session Control Function (S-CSCF) module in accordance with the response from the HSS; and

reselecting an S-CSCF if receiving no response from the S-CSCF within a prescribed period of time, and sending a SIP request to the selected S-CSCF.

7. A session processing method in an Internet Protocol multimedia subsystem, comprising:

discovering, by an Interrogating-Call Session Control Function (I-CSCF) module, that an Serving-Call Session Control Function S-CSCF module currently serving a user is in an unavailable state, and selecting, by the I-CSCF, an S-CSCF other than the unavailable S-CSCF, and routing all calls of the called user to the reselected S-CSCF for processing.

8. The session processing method in an Internet Protocol multimedia subsystem according to claim 7, wherein the process of selecting, by the I-CSCF, an S-CSCF other than the unavailable S-CSCF comprises:

obtaining, by the I-CSCF, a set of S-CSCF capabilities required by the called user; and

selecting, by the I-CSCF, an S-CSCF other than the unavailable S-CSCF in accordance with the set of S-CSCF capabilities.

9. The session processing method in an Internet Protocol multimedia subsystem according to claim 8, wherein the process of obtaining, by the I-CSCF, a set of S-CSCF capabilities required by the called user comprises:

requesting, by the I-CSCF, the HSS for information on the set of capabilities; and

returning, by the HSS, the information on the set of capabilities to the I-CSCF on receiving the request, on perceiving that the S-CSCF currently serving the user is unavailable.

10. The session processing method in an Internet Protocol multimedia subsystem according to claim 9, wherein the I-CSCF requests the information on the set of capabilities by sending to the HSS a location information request which is extended by newly adding in the location information request command an information element comprising at least the value of the request for the information on the set of capabilities;

the HSS considers that the location information request is a query about user location information if the request does not comprise the newly added information element; and

the HSS determines whether the request belongs to a request for the information on the set of capabilities after determining whether the request comprises the newly added information element and the value of the newly added information element.

11. The session processing method in an Internet Protocol multimedia subsystem according to claim 10, wherein the location information request command comprises Cx-Location-Query and Cx-Select-Pull;

if the location information request command is Cx-Location-Query, the process of newly adding an information element comprises adding a location query type AVP (User-Location-Type AVP) parameter in the command; and

if the location information request command is Cx-Select-Pull, the process of newly adding an information element comprises modifying an IMPI attribute type as being conditional.

12. The session processing method in an Internet Protocol multimedia subsystem according to claim 9, wherein the HSS checks whether to allow the I-CSCF to perform the reselection on receiving the request in a manner that if the HSS considers that the current S-CSCF can resume on its own initiative so that it is unnecessary for the I-CSCF to perform the reselection, the HSS returns an error code in a response message to the request for the set of capabilities to notify the I-CSCF of unnecessary reselection;

otherwise the HSS allows the I-CSCF to perform the reselection and returns the information on the set of capabilities.

13. The session processing method in an Internet Protocol multimedia subsystem according to claim 9, wherein the I-CSCF supporting the reselection of an S-CSCF carries an information element SupportFeature in the first user location information command and indicates in the information element that the I-CSCF supports the reselection feature;

the HSS also carries an information element SupportFeature in the response and lists therein its supported features;

the I-CSCF further determines whether the HSS also supports the reselection on receiving the response;

if yes, the I-CSCF further requests explicitly for the information on the set of capabilities;

if it is indicated in the response that the HSS does not support the reselection or the information element is not present in the response, the I-CSCF returns a failure response to the calling party without performing the reselection of any S-CSCF.

14. The session processing method in an Internet Protocol multimedia subsystem according to claim 10, wherein the I-CSCF supporting the reselection of an S-CSCF carries an information element SupportFeature in the first user location information command and indicates in the information element that the I-CSCF supports the reselection feature;

the HSS also carries an information element SupportFeature in the response and lists therein its supported features;

the I-CSCF further determines whether the HSS also supports the reselection on receiving the response;

if yes, the I-CSCF further requests explicitly for the information on the set of capabilities;

if it is indicated in the response that the HSS does not support the reselection or the information element is not present in the response, the I-CSCF returns a failure response to the calling party without performing the reselection of any S-CSCF.

15. An Interrogating-Call Session Control Function I-CSCF in an Internet Protocol multimedia subsystem, wherein the I-CSCF is configured to receive an initial request for a called user, inquire a Home Subscriber Server (HSS) about the registration location of the called user, send a Session Initiation Protocol (SIP) request to a Serving-Call Session Control Function (S-CSCF) module according to a response from the HSS, reselect an S-CSCF if receiving no response from the S-CSCF within a prescribed period of time, and send a SIP request to the reselected S-CSCF.

16. The I-CSCF in an Internet Protocol multimedia subsystem according to claim 15, wherein the I-CSCF is further configured to obtain a set of S-CSCF capabilities required by the called user, reselect an S-CSCF in accordance with the set of S-CSCF capabilities.

17. The I-CSCF in an Internet Protocol multimedia subsystem according to claim 15, wherein the I-CSCF is further configured to obtain a set of S-CSCF capabilities required by the called user from HSS by modifying a command Cx-Location-Query or Cx-Select-Pull, wherein modifying a command Cx-Location-Query comprises adding a user location query type parameter User-Location-Type AVP in the command;

and modifying a command Cx-Select-Pull comprises modifying the IMPI attribute type of the command as being conditional.