Private automatic branch exchanges

This paper describes different units designed to meet varying conditions and capacities by the Bell Telephone Manufacturing Co. of Antwerp. The 4- and 6-line units with one junction line are of the all-relay type and replace the old-fashioned intercommunication systems. The capacity of these small units makes them suitable for private residences and small offices of all kinds. Experience has shown that there is a real demand for this type and the Belgian Government has installed over 1200 of these on a rental basis in a little more than one year. They are fed from an all-mains power unit (no battery), consisting of metal rectifier, transformer and filter. This current unit is suitable for connection to a.c. mains of 110, 130, 160, or 220 V. Transfer arrangements are provided by which an incoming call may be transferred to another person or department. No special attendant or equipment is required. Other units have been developed using single-motion switches of varying capacities. Ratchet drive is used for switches of 11, 30 and 50 points; 100-point switches are of the standard rotary gear-driven finder type. Photographs and diagrams of the various units accompany the paper.