Patent ID: 8170622

Claim:
A mobile station device capable of communicating with a plurality of mobile communication systems within a mobile communication network system, each of the plurality of mobile communication systems corresponding to a different communication method, the mobile station device comprising: a plurality of wireless interfaces each implementing any one of the different communication methods; a power control unit controlling the plurality of wireless interfaces such that any one of the plurality of wireless interfaces becomes communication-enabled, wherein the communication-enabled wireless interface is set as a waiting wireless interface; a comparing unit comparing, based on an incoming notification received by the waiting wireless interface, a requested mobile communication system designated by information included in the incoming notification with a mobile communication system corresponding to the communication method implemented by the waiting wireless interface; a switchover unit directing the power control unit to switchover the wireless interface implementing the communication method of the requested mobile communication system to be communication-enabled, when the comparing unit judges that the requested mobile communication system is different from the mobile communication system implemented by the waiting wireless interface; and a transmitting unit transmitting a location registering request, for informing the mobile communication system corresponding to the communication method implemented by the waiting wireless interface, through the post-switchover wireless interface.