Design of an Automatic Telephone Intercept Switch

A system has been designed to automatically perform the functions of intercepting misdirected telephone calls and providing correct dialing information. This paper concentrates on the design of the switching unit of the system. The switch is a space-division, wired-logic controlled device using dry-reed relays as crosspoints. It is organized so that separate networks perform the functions of concentrating incoming lines and selecting operator positions for identification of the number the customer thinks he called. While the presently installed system is not completely automatic, provision is made for incorporation of automatic identification of the “called number” when the necessary telephone central office features become available. Although the system was built for a particular telephone installation, modular construction makes it readily adaptable to installations with a variety of requirements. The switching networks can handle a maximum of 200 incoming intercept trunks, 64 automatic audio response trunks, 22 called-number identifying operators, and 14 special intercept operators.