Party line telephone system

摘要

A party line telephone system capable of effecting selective calling from one station to another and particularly adapted for use in battery-powered two-wire telephone systems such as those used in underground mines where consideration of intrinsic safety, low power consumption and compatibility with existing equipment are paramount. The system of the invention is such that the receiver at each station in the network need not be connected to a battery-powered source for any prolonged period of time except when that station is being called by another station for a private conversation, thereby conserving battery power.