Direct Distance Dialing - History

History

The telephone industry made a United States "first" in the New Jersey communities of Englewood and Teaneck with the introduction of what is known now as direct distance dialing. Starting on November 10, 1951, customers of the ENglewood 3, ENglewood 4 and TEaneck 7 exchanges (who could already dial New York City and area) were able to dial 11 cities across the United States, simply by dialing the three-digit area code and the seven digit number (which at the time consisted of the first two letters of the exchange name and five digits).

The 11 cities and their area codes at that time were:

• Boston, Massachusetts (617)
• Chicago, Illinois (312)
• Cleveland, Ohio (216)
• Detroit, Michigan (313)
• Milwaukee, Wisconsin (414)
• Oakland, California (415)
• Philadelphia, Pennsylvania (215)
• Pittsburgh, Pennsylvania (412)
• Providence, Rhode Island (401)
• Sacramento, California (916)
• San Francisco (318) – San Francisco required the special area code 318 for temporary routing requirements

Many other cities could not yet be included as they did not yet have the necessary switching equipment to handle incoming calls automatically on their long-distance calling circuits. Other cities still had either a mixture of local number lengths or were all still six-digit numbers; Montreal and Toronto, Canada, for example, had a mix of six- and seven-digit numbers from 1951 to 1957, and did not have DDD until 1958. Whitehorse, Yukon, had seven-digit numbers from 1965, but the necessary switching equipment was not in place locally until 1972.