For the purpose of being capable of performing direct inter-handset communications while maintaining inter-handset communications via a base unit, smoothly making a transition from inter-handset communications via a base unit to direct inter-handset communications, and switching to inter-handset communications via a base unit without releasing the communications even in case direct inter-handset communications cannot be established, a local handset includes a direct inter-handset communications controller and a direct inter-handset communications transition controller for making control to establish direct inter-handset communications while maintaining communications with a base unit as well as transmitting control channels for direct inter-handset communications in vacant slots in the receiving time zones for communications with the base unit, while a distant handset includes a direct inter-handset communications controller and a direct inter-handset communications transition controller for scanning control channels for direct inter-handset communications in the time zones other than the slots occupied by communications with the base unit 100.