Abstract: A remote transmitting or receiving device (T/R device) communicates with a conventional subscriber telephone through available AC power wires which carry signals that may be modulations of RF carrier frequencies and which are coupled to the power wires. For example, an incoming telephone call includes signals that are detected and modulate a master RF carrier frequency which is coupled to the AC power wires at the telephone line location and these signals are coupled from the AC power wires at a remote R device location, and, demodulated and used to control an electrical appliance, motor, pump, etc. The remote T device which may be, for example, a fire detector produces signals which modulate a remote RF carrier frequency which is coupled to the AC power wires at the remote location and this modulated carrier is coupled from the AC power wires and demodulated at the telephone line location to control or initiate signals in suitable form for transmission over the telephone line.

Abstract: An extension telephone system communicates with a conventional subscriber telephone line where the subscriber's line telephone is located, through available AC power wires which carry signals that may be modulations of RF carrier frequencies and which are coupled to the power wires. Incoming telephone line signals are detected and modulate a first RF carrier frequency which is coupled to the AC power wires at the line telephone location and these signals are coupled from the AC power wires at an extension telephone location, and, demodulated and fed to an extension telephone which is energized by DC power derived from the AC power wires at the extension location.