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The General Toll Switching Plan was a system manually operated by long-distance telephone operators. It was the forerunner of an automated system called Nationwide Operator Toll Dialing that was begun in 1943, which eventually led to Direct Distance Dialing (DDD) within the framework of the North American Numbering Plan decades later.
PSTN network topology is the switching network topology of a telephone network connected to the public switched telephone network (PSTN).. In the United States and Canada, the Bell System network topology was the switching system hierarchy implemented and operated from c. 1930 to the 1980s for the purpose of integrating the diverse array of local telephone companies and telephone numbering ...
The No. 4 Electronic Switching System (4ESS) is a class 4 telephone electronic switching system that was the first digital electronic toll switch introduced by Western Electric for long-distance switching. It was introduced in Chicago in January 1976, to replace the 4A crossbar switch. [1]
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. [1]
On motorways distance marker posts also bear an arrow pointing towards the location of the nearest emergency telephone. [4] The number used on distance marker posts is also encoded into the numbers associated with motorway emergency roadside telephones. [5] In this way motorway control centre staff can pinpoint the telephone from which a call ...
A marker is a type of special purpose control system that was used in electromechanical telephone central office switches. Switches employing markers belong to a class of switches known as " common control ", as the purpose of a marker is to control the closure of contacts in the switching fabric that connect a circuit between the calling party ...
The Number Five Crossbar Switching System (5XB switch) is a telephone switch for telephone exchanges designed by Bell Labs and manufactured by Western Electric starting in 1947. It was used in the Bell System principally as a Class 5 telephone switch in the public switched telephone network (PSTN) until the early 1990s, when it was replaced ...
List of the mainly electro mechanical switching systems from Hasler AG Bern, which were used in public telephone network in Switzerland for many decades. Hasler AG finally merged into Ascom in 1987. HS 25 (modified from the Ericsson OL-100 system with double relays and 25-point selector (Ericsson license), mainly used for small villages and ...