Patent ID: 9578068
Date: 2017-02-21
CPC Classifications: H04L,H04W

Claim:
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.