Patent ID: 8682382

Claim:
A mobile terminal apparatus capable of standing by while switching among a plurality of communication systems, wherein each one of the plurality of communication systems operates in a frequency band different from at least one other of the plurality of communication systems, comprising: a communication part capable of selecting a first one of the plurality of communication systems and wirelessly communicating with a base station of the first one of the plurality of communication systems; and a control part capable of changing the first one of the plurality of communication systems used by the communication part and making the communication part perform wireless communication, wherein the control part comprises a neighbor base station information acquisition part using the communication part to obtain neighbor base station information from the base station of the first one of the plurality of communication systems, a signal strength monitoring part monitoring a signal strength from the base station of the first one of the plurality of communication systems used by the communication part, a system hand-off part performing hand-off to a base station of a second one of the plurality of communication systems stored in the neighbor base station information when the present signal strength becomes lower than a predetermined amount, wherein the second one of the plurality of communication systems is different from the first one of the plurality of communication systems, a reselection processing part performing reselection processing to release a session of the first one of the plurality of communication systems, attempt acquisition for the plurality of communication systems, and attempt position registration in a successfully acquired second one of the plurality of the communication systems, wherein the reselection processing is not a handover processing, and a reselection inhibition part selecting a first mode of inhibiting the reselection processing, when neighbor base station information received at the neighbor base station information acquisition part includes information indicating a base station of the second one of the plurality of communication systems, or selecting a second mode not inhibiting the reselection processing when the neighbor base station information does not include the information indicating a base station of the second one of the plurality of communication systems.