SUBSCRIBER TERMINAL UNIT FOR TELEPHONE CARRIER SYSTEM

摘要

The disclosure relates to a subscriber terminal for a telephone communication system which is adapted for connection to a cable transmission pair from a central office to supply an additional facility without affecting the original system. The subscriber terminal utilizes a rechargeable battery which furnishes power to its receiver and transmitter sections which operate at frequencies different from those of the physical communication system. The battery is controlled by a charging circuit so as to be charged by the central office power supply during nonoperation of the physical system.