Telephone signal multiplexing system

Abstract

A communications system includes self synchronizing device sets such as telephones that are interconnected by wiring to allow communication between the devices and communication with an outside communication line, such as a subscriber telephone line provided by a central telephone company. Each individual device includes access circuitry for placing signals on the interconnecting wires so that the signals from the various devices are time division multiplexed on the same wire conductors. The individual communication sets are synchronized without the intervention of a central controller. Each set is assigned a unique identification code. Each set then listens for the identification codes placed on the interconnection wiring by the other sets and places its signal on the wiring at the proper time in response to the other detected identification codes. The access circuitry may be constructed to use conventional four conductor telephone interconnection wiring so that the two conductors conventionally used for auxiliary, dial light power are also used for multiplexed signal transmissions.