Patent ID: 8559419

Claim:
A method of progressing a terminating call in an IP Multimedia Subsystem (IMS), wherein the terminating call addresses a given IMS public identity (IMPU), which is shared amongst more than one IMS private identity (IMPI) of an IMS subscription, the method comprising the steps of: at a Home Subscriber Server (HSS), which holds IMS subscriptions for subscribers of the IMS, configuring said more than one IMPI sharing the given IMPU with a number of policies to be applied per IMPI on how to progress the terminating call; receiving at the HSS from an Interrogating Call Session Control Function (I-CSCF), which is in charge of selecting a Serving Call Session Control Function (S-CSCF) for handling the terminating call, a query about a subscriber identified by the given IMPU; determining at the HSS amongst said more than one IMPI sharing the given IMPU at least one IMPI for which the number of policies allow for progressing the terminating call; where the at least one IMPI is found, answering from the HSS to the I-CSCF either capabilities required from an assignable S-CSCF, or an identifier of a previously assigned S-CSCF, or where no IMPI is found for which the number of policies allow for progressing the terminating call, answering from the HSS to the I-CSCF with an error condition to avoid progressing the call; receiving at the HSS a registration from a S-CSCF assigned to handle the terminating call; and downloading a user profile for the given IMPU from the HSS towards the assigned S-CSCF currently handling the terminating call.