Patent ID: 8477688

Claim:
A method for notifying a state of a user to an Application Server (AS), comprising: receiving, by a Serving-Call Session Control Function (S-CSCF), new service profile information of the user sent from a Home Subscriber Server (HSS) when the user's service profile changes, comparing, by the S-CSCF, a new Initial Filter Criteria (iFC) carried in the new service profile information with an original iFC stored in the S-CSCF; and sending, by the S-CSCF, registration information of the user to an AS matching a registration message trigger criteria which is determined as being newly added in the new iFC, wherein after comparing the new iFC carried in the new service profile information with the original iFC stored in the S-CSCF, the method further comprises: generating and sending, by the S-CSCF, a cancel subscription message to an AS matching a registration message trigger criteria which is determined as being removed from the new iFC, so that the registration information of the user is sent to the AS matching the removed registration message trigger criteria.