Abstract: An interconnect circuit arrangement for patching a simplex or half-duplex radio network into a standard telephone system. It includes means for sending beep tones to the parties at the end of each message so that they can readily recognize when each is supposed to talk. The tones are sent automatically when the party on the telephone system concludes his messages, and under manual control of the party at the radio end when he concludes his. Special access codes are provided to prevent unauthorized access to the radio system and to set the circuit for special functions. Various override features are included to facilitate operation and avoid time delays that have heretofore tended to hinder conversations in VOX simplex and half-duplex radio systems.