Patent ID: 8279854

Claim:
A method for deregistering a wireless IP access network contact address, comprising: notifying, by a terminal equipment (TE), an IP multimedia subsystem (IMS) network to deregister a contact address of the TE in a first wireless IP access network through a currently available access network of the TE other than the first wireless IP access network, if the contact address of the TE in the first wireless IP access network is not deregistered to the IMS network when the TE leaves the first wireless IP access network; and wherein the notifying the IMS network to deregister the contact address of the TE in the first wireless IP access network through the current available access network of the TE further comprises: notifying a service call session control function (S-CSCF) of the IMS network to deregister the contact address of the TE in the first wireless IP access network through the current available access network of the TE.