In a multi-channel radio telephone system, each mobile station is assigned a home channel for receiving calls but can initiate calls on any idle channel. Communication is normally in a duplex mode but automatically reverts to semi-duplex when a calling mobile initiates a call to a called mobile on the called mobile's home channel. Automatic subscriber ticketing is accomplished at the base station, and each channel communicates with the public telephone system via a respective dedicated line. A non-subscribing mobile attempting to initiate a call on the system is automatically connected to the base station operator for completion of the call, the caller's I.D. number being automatically displayed for the operator. When called, a mobile automatically returns a decode complete signal to the base station. If the decode complete signal is not received within a predetermined time interval, the call is terminated and the base station automatically proceeds to determine if the called mobile is busy or out-of-service and returns a corresponding signal to the calling party. The mobiles are adapted to operate in other systems wherein the normally assigned home channel is unavailable. In such cases the mobile automatically seeks a channel bearing a predetermined code which identifies that channel as an alternate home channel for the mobile.