Communications system for internal company use - has interfaces to allow handling of various terminal types and methods of transmission

摘要

The internal communications system e.g. for electricity supply comprises includes telephone sets, teleprinter terminals, branch exchanges and interconnecting lines and handles different types of signal transmission, e.g. voice signals via wires or free space, carrier frequencies, d.c. and a.c. telegraphy. All terminals connected to one exchange have connecting units connected by a call device to the exchange's central control unit in the same way. These connecting units act as interfaces which supply binary signals representing the characteristic circuit states to the central unit and convert incoming selection information into binary coded data for the exchange.