Methods and apparatus for processing an IMS session

Patent metadata

Field	Value
Publication number	US-9578068-B2
Application number	US-201214429566-A
Country	US
Kind code	B2
Filing date	Sep 24, 2012
Priority date	Sep 24, 2012
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

There is provided a method of processing an IMS session originated by a UE after restart of a S-CSCF that was previously assigned to a user of the UE during registration with the IMS, when a further S-CSCF is currently assigned to the user. The method comprises, at a HSS, receiving a request to register a user identity of the user from the previously assigned S-CSCF, determining that the previously assigned S-CSCF is not the same as a S-CSCF currently assigned to the user, determining if IMS restoration procedures are supported for the UE, and, if IMS restoration procedures are not supported for the UE, sending a response to the previously assigned S-CSCF, the response identifying the further S-CSCF currently assigned to the user.

First claim

The invention claimed is:

1. A method of processing an IP Multimedia Subsystem (IMS) session originated by a User Equipment (UE) after restart of a Serving Call Session Control Function (S-CSCF) that was previously assigned to a user of the UE during registration with the IMS, when a further S-CSCF is currently assigned to the user, the method comprising, at a Home Subscriber Server (HSS):
receiving a request to register a user identity of the user from the previously assigned S-CSCF;
determining that the previously assigned S-CSCF is not the same as a S-CSCF currently assigned to the user;
determining if IMS restoration procedures are supported for the UE; and
if IMS restoration procedures are not supported for the UE, sending a response to the previously assigned S-CSCF, the response identifying the further S-CSCF currently assigned to the user.

2. The method of claim 1 , wherein receiving a request to register a user identity of the user comprises:
receiving a Diameter protocol Server-Assignment-Request (SAR) message, the SAR message including an identifier of the previously assigned S-CSCF and having a Server Assignment Type indicating NO_ASSIGNMENT.

3. The method of claim 1 , wherein sending a response to the previously assigned S-CSCF comprises:
generating and sending a Diameter protocol Server-Assignment-Answer (SAA) message, the SAA message having a Result Code indicating DIAMETER_IDENTITY_ALREADY_REGISTERED and including an identifier of the further S-CSCF currently assigned to the user.

4. A method of processing an IP Multimedia Subsystem (IMS) session originated by a User Equipment (UE) after restart of a Serving Call Session Control Function (S-CSCF) that was previously assigned to a user of the UE during registration with the IMS, when a further S-CSCF is currently assigned to the user, the method comprising, at the previously assigned S-CSCF:
upon receipt of a session establishment request for the session from a Proxy Call Session Control Function (P-CSCF) generating and sending a request to register a user identity of the user to a Home Subscriber Server (HSS), the request to register the user identity of the user including an indication as to whether the UE supports IMS restoration procedures;
receiving a response from the HSS, the response identifying the further S-CSCF currently assigned to the user; and
generating and sending a session establishment response to the P-CSCF, the session establishment response indicating that the session establishment request should be redirected to the further S-CSCF.

5. The method of claim 4 , wherein the session establishment response comprises a Session Initiation Protocol (SIP) Use Proxy message that specifies an identifier of the further S-CSCF to be used for redirection in a Contact header field.

6. The method of claim 4 , wherein the request to register a user identity of the user comprises a Diameter protocol Server-Assignment-Request (SAR) message, the SAR message including an identifier of the previously assigned S-CSCF and having a Server Assignment Type indicating NO_ASSIGNMENT.

7. The method of claim 4 , wherein the response from the HSS comprises a Diameter protocol Server-Assignment-Answer (SAA) having a Result Code indicating DIAMETER_IDENTITY_ALREADY_REGISTERED and including an identifier of the further S-CSCF currently assigned to the user.

8. The method of claim 4 , further comprising:
upon receipt of the session establishment request for the session, determining if the UE is identified in a list of UEs that support IMS restoration procedures and, if not, including an indication that the UE does not support IMS restoration procedures in the request to register a user identity of the user.

9. The method as claimed of claim 4 , further comprising:
including in the session establishment response an indication that future requests received from the UE should be routed to the further S-CSCF.

10. An apparatus configured to operate as a Home Subscriber Server (HSS) of an IP Multimedia Subsystem (IMS) the apparatus comprising:
a receiver configured to receive a request to register a user identity of a user from a Serving Call Session Control Function (S-CSCF) that was previously assigned to the user during registration with the IMS;
a processor configured to determine if the previously assigned S-CSCF is the same as a S-CSCF currently assigned to the user and, if the previously assigned S-CSCF is not the same as the S-CSCF currently assigned to the user, to determine if IMS restoration procedures are supported for the UE;
the processor being further configured to generate a response and, if it is determined that IMS restoration procedures are not supported for the UE, to include an identifier for the S-CSCF currently assigned to the user in the response; and
a transmitter configured to send the response to the previously assigned S-CSCF.

11. The apparatus of claim 10 , wherein the receiver is configured to receive a request to register a user identity of the user that comprises a Diameter protocol Server-Assignment-Request (SAR) message, the SAR message including an identifier of the previously assigned S-CSCF and having a Server Assignment Type indicating NO_ASSIGNMENT.

12. The apparatus of claim 10 , wherein the processor is configured to generate a response that comprises a Diameter protocol Server-Assignment-Answer (SAA) message, the SAA message having a Result Code indicating DIAMETER_IDENTITY_ALREADY_REGISTERED and including an identifier of the S-CSCF currently assigned to the user.

13. An apparatus configured to operate as an IP Multimedia Subsystem (IMS) Serving Call Session Control Function (S-CSCF) the apparatus comprising:
a receiver configured to receive, from a Proxy Call Session Control Function (P-CSCF) a session establishment request originated by a User Equipment (UE) of a user;
a processor configured to determine if a user profile for the user of the UE should be retrieved and, if so, to generate a request to register a user identity of the user, the request to register the user identify of the user including an indication as to whether the UE supports IMS restoration procedures;
a transmitter configured to send the request to register a user identity of the user to a Home Subscriber Server (HSS);
the receiver being further configured to receive a response from the HSS that includes an identifier of a further S-CSCF that is currently assigned to the user;
the processor being further configured to generate a session establishment response indicating that the session establishment request should be redirected to the further S-CSCF; and
the transmitter being further configured to send the session establishment response to the P-CSCF.

14. The apparatus of claim 13 , wherein the processor is configured to determine that a user profile for the user should be retrieved if data stored by the S-CSCF does not include the user profile.

15. The apparatus of claim 13 , wherein the processor is configured to generate a session establishment response that comprises a Session Initiation Protocol (SIP) Use Proxy message that specifies an identifier of the further S-CSCF to be used for redirection in a Contact header field.

16. The apparatus of claim 13 , wherein the processor is configured to generate a request to register a user identity of the user that comprises a Diameter protocol Server-Assignment-Request (SAR) message, the SAR message including an identifier of the previously assigned S-CSCF and having a Server Assignment Type indicating NO_ASSIGNMENT.

17. The apparatus of claim 13 , wherei

Assignees

• Ericsson Telefon Ab L M
• ERICSSON TELEFON AB L M (publ)

Inventors

• Merino Vazquez Emiliano
• Austrell Tobias
• Fernandez Galmes Juan Manuel
• Perez De Villar Caamaño Bernardo

Classifications

• H04W8/04

  Registration at HLR or HSS [Home Subscriber Server] · CPC title

• H04L69/40

  for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection (management of faults, events, alarms or notifications in data switching networks H04L41/06) · CPC title

• H04L65/80

  Responding to QoS · CPC title

• H04L65/1016 Primary

  IP multimedia subsystem [IMS] · CPC title

• H04W60/00

  Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration · CPC title