PURPOSE: To impartially process all the waiting of subscriber mobile stations, by performing reserved registration for a base station, when no vacant communication channel exists in the base station.

CONSTITUTION: The information whether or not a vacant communication channel exists is transmitted on a control channel 4 from a base station, and when no vacant communication channel exists, the information whether or not the reserved registration is possible is transmitted. At a mobile station, the channel selection at an outgoing call is controlled according to the information from the control channel, and when the vacant channel exists, the mobile station is connected to the vacant channel designated by the base station, and when the reserved registration is possible, the reservation is done. When the reserved registration is impossible, it is displayed and as soon as a vacant channel is generated after the communication traffic is usable, the call can be permitted in the order of registration.