A method and system for radio communication between at least one parent communication unit and a plurality of slave communication units. A slave communication unit transmits an automatic answer signal in response to an incoming call receipt signal transmitted from the parent communication unit. When one of the slave communication units makes a called-person's answer to the incoming call receipt signal, it transmits a called-person's answer signal. If interference occurs between the automatic and called-person's answer signals, the parent communication unit provides a command, causing the slave communication units to stop the automatic and called-person's answer signals and permits the slave communication unit which transmits the called-person's answer signal to communicate with the parent communication unit.