Patent ID: 8693312

Claim:
A method for processing a registration exception in a user registration procedure in an IP Multimedia Subsystem (IMS) network; comprising: requesting a Home Subscriber Server (HSS) to allocate a first Service-Call Session Control Function (S-CSCF) in a registration procedure according to a registration request that does not carry information about whether the registration request is a protected registration request; forwarding the registration request to the first S-CSCF according to S-CSCF-associated information carried in a response from the HSS; determining whether the registration request is an initial registration or a re-registration according to information carried in the registration request; and returning, when a registration exception occurs, a registration failure massage message to a terminal initiating the registration request or selecting a second S-CSCF, according to: information indicating whether the registration request is an initial registration or a re-registration carried in the registration request.