Patent ID: 8442491

Claim:
A method for providing roaming service in a wireless communication system, the method comprising: receiving an authentication request for a roaming mobile station (MS), which roams from an Internet protocol multimedia subsystem (IMS) network to a circuit switched (CS) network, from a mobile service center (MSC) of the CS network by a roaming gateway (RGW) performing communication between the IMS network and the CS network; acquiring authentication information for the roaming MS and service information for supplementary services with which the roaming MS has been provided from the IMS network, in response to the authentication request; checking if the roaming MS is entitled to use the supplementary services according to the service information, using the authentication information and the service information; if the roaming MS is entitled to use the supplementary services, sending an authentication success message to the MSC; and sending the service information to the MSC so as for the roaming MS to be provided with the supplementary services according to the service information in the CS network.