Switchboards and Signaling Facilities of the Teletypewriter Exchange System

N A T I O N W I D E teletypewriter service giving direct connection between subscribers for the exchange of written messages by means of the teletypewriter in a manner similar to the service offered by the telephone system for the exchange of spoken messages was offered to the public as a new aid to business by the Bell System on November 21, 1931. This service, known as the teletypewriter exchange ( T W X ) service, introduced a switching technique which, although familiar in the telephone art, involved many new technical problems when applied to the telegraph art. Records show that during the nineteenth century some telegraph exchanges were established at which connections could be made on a message basis for to and fro telegraph communications between subscribers. These earlier exchanges had a commercial appeal although the various forms of subscriber instruments then used were slow and required considerable skill for operation. Later, when the telephone was introduced, these exchanges gradually disappeared because the public naturally preferred the more convenient instrument. With the introduction of the modern teletypewriter the telegraph exchange idea was again revived because the teletypewriter, being very similar to an ordinary typewriter and permitting an accurate written record of a to and fro communication, has, from a subscriber standpoint, overcome the objectional features of the early telegraph instruments. T h e private line telegraph and teletypewriter service furnished by the Bell System has formed a very important background for the new teletypewriter exchange service.