Toll switching trunk

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In telecommunication, a toll switching trunk or toll connecting trunk [1] is a trunk connecting an end office to a toll center as the first stage of concentration for intertoll or long-distance traffic.

Operator assistance or participation may be an optional function. In U.S. common carrier telephony service, a toll center designated Class 4C is an office where assistance in completing incoming calls is provided in addition to other traffic; a toll center designated Class 4P is an office where operators handle only outbound calls, or where switching is performed without operator assistance. [2]

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Operator Toll Dialing was a telephone call routing and toll-switching system for the Bell System and the independent telephone companies in the United States and Canada that was developed in the 1940s. It automated the switching and billing of long-distance calls. The concept and technology evolved from the General Toll Switching Plan of 1929, and gained technical merits by the cutover of a new type of crossbar switching system in Philadelphia to commercial service in August 1943. This was the first system of its kind for automated forwarding of calls between toll switching centers, but it served customers only for regional toll traffic. It established initial experience with automatic toll switching for the design of a nationwide effort that was sometimes referred to as Nationwide Operator Toll Dialing.


  1. The Digital Future, 1979 Toll connecting trunk
  2. "4A Toll Switching System" (PDF). Archived (PDF) from the original on 2022-10-09.

See also