Telephone exchange

In the field of telecommunications, a telephone exchange (US: telephone switch) is a piece of equipment that connects phone calls. It is what makes phone calls "work" in the sense of making connections and relaying the speech information.

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The term exchange can also be used to refer to an area served by a particular switch. And more narrowly, it can refer to the first three digits of the local number.

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In the past, the first two or three digits would map to a mnemonic exchange name, e.g. 869–1234 was formerly TOwnsend 9–1234, and before that (in some localities) might have been TOWnsend 1234 (only the capital letters and numbers being dialed).

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In December of 1930, New York City became the first locality in the United States to adopt the two-letter, five-number format; it remained alone in this respect until well after World War II, when other municipalities across the country began to follow suit (in some areas, most notably much of California, telephone numbers in the 1930s through early 1950s consisted of only six digits, two letters which began the exchange name followed by four numbers, as in DUnkirk 0799). Prior to the mid-1950s, the number immediately following the name could never be a "0" or "1;" indeed, "0" was never pressed into service at all, except in the immediate Los Angeles area (the "BEnsonhurst 0" exchange mentioned in an episode of the popular TV sitcom The Honeymooners was fictitious).

Related Topics:
December - 1930 - New York City - United States - World War II - California - 1930s - 1950s - Los Angeles - The Honeymooners

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In 1955, the Bell System attempted to standardize the process of naming exchanges by issuing a "recommended list" of names to be used for the various number combinations. In 1961, New York Telephone introduced "selected-letter" exchanges, in which the two letters did not mark the start of any particular name (example: FL 6-9970), and by 1965 all newly-connected phone numbers nationwide consisted of numerals only (Wichita Falls, Texas had been the first locality in the United States to implement the latter, having done so in 1958; meanwhile, pre-existing numbers continued to be displayed the old way in many places well into the 1970s).

Related Topics:
1955 - Bell System - 1961 - 1965 - Wichita Falls, Texas - United States - 1958 - 1970s

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Most of the United Kingdom had no lettered telephone dials until the introduction of Subscriber Trunk Dialling (STD) in 1958. Only the director areas (Birmingham, Edinburgh, Glasgow, Liverpool, London and Manchester) and the non-director areas adjacent to them had lettered dials, and the exchanges used the three-letter, four-number format until conversion to all-figure numbering in 1968.

Related Topics:
United Kingdom - Subscriber Trunk Dialling - 1958 - 1968

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In the United States, the word exchange can also have the technical meaning of a local access and transport area under the Modification of Final Judgment (MFJ).

Related Topics:
United States - Local access and transport area - Modification of Final Judgment

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