Telephone exchange names

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During the early years of telephone service, communities that required more than 10,000 telephone numbers, whether dial service was available or not, utilized exchange names to distinguish identical numerics for different customers.

When dial service was introduced (typically during the period of 1910 to 1960) in such multiple exchange communities, typically, customers would dial the first two or three letters of the exchange name, followed by the numeric digits.

London, England, is most notable for using the first three letters, then the last four digits. New York, USA, was the first American location to use so-called "2-5 numbers", two letters and five numbers. This became the North American standard as long distance service (Direct Distance Dialing came into use through the 1950s.

As demand for phone service grew, the supply of assignable phone numbers began to dwindle, and several North American area codes were split to enable reuse of numbers. As the growth accelerated, the decision was made to switch to All-Number Calling (ANC), since there were several unpronounceable letter combinations that were not being used. This allowed more efficient use of the number supply, and there were only two area code splits between 1962 and 1981.

The standard format for displaying telephone numbers that used exchange names was to capitalize the first few letters if they were dialed, e.g.,

MUrray Hill 5-9975 (one of the Ricardos' numbers on I Love Lucy - note that the H in Hill, although not dialed, is still capitalized)
GRamercy 5-1234 (typical North American, in New York or continent-wide after about 1950)
BAldwin 6828 (typical urban North American before move to seven-digit numbers)
BUCkingham 3376 (typical London, England, style up to early 1960s)

If they were not dialed, it was more common to only capitalize the first letter of each part of the exchange name, e.g.,

Metcalfe 6000
Fairmont 3335
Metcalfe 200
Fairmont 50

Such numbers could be of non-standard length, simply because they were not dialed, but quoted to an operator that plugged into the appropriate line.

At least one song has been written that uses an exchange name: "PEnnsylvania Six, Five Thousand" (PE 6-5000).

The use of letters in exchange names resulted in placement of letters on the telephone dial. Some areas were not standard (notably Calgary) until later in history. Europe and North America differ in placement of the letter O, and countries with non-English languages differ again.

Links

[Telephone Exchange Name Project]

[Official listing of Ma Bell's recommended names]

[Listing of names for Los Angeles County]

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