Abstract: A radio telephone system comprising a base station and a plurality of portable units. The base station transmits information to portable units on a first frequency and the portable units transmit information to the base station on a second frequency. Each of the frequencies is divided into a number of communications channels by time division multiplexing. In one aspect the portable units include means for detecting the calling signal assigned to a particular portable unit which calling signal is sent by the base station and to cooperate with a switch to apply signals to a gate which then energizes an alarm at the particular portable unit to indicate to a person at the portable unit that the base station is calling. In another aspect the system includes a scanner and a channel seizing means which are both coupled to the receiver of the system and to each other.