Exchanges in Washington, D. C.



The history of the telephone exchange names in Washington, D. C., as in most significant United States cities, can be divided into three periods:

  1. The pre-dial period, when all telephone calls were completed by manual action by operators, and there were no constraints on exchange names other than that there was no likelihood of confusion when a customer gave the name to the operator,
  2. The early dial period, in which the Washington, D. C. telephone numbers were set up to accommodate dialing the first two letters of an exchange name followed by a four-digit number designating the individual line, though in fact not all exchanges provided for dialing by the phones in those exchanges, and
  3. The late dial period, in which, instead of the first two letters of an exchange name alone, one dialed the first two letters and an "office number" (This was the terminology used in an early New York City directory, though it was not common terminology in this period), again followed by four digits designating the individual line.

The current tables derive from only one directory, near the end of the late dial period, when all-number calling was being phased in, and therefore does not include any data from the first two periods or the earliest part of the late dial period. This deficiency will be remedied as data are accumulated so that they can be posted here.

Other regional tables:




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Last modified February 19, 2015.

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