Direct distance dialing

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Direct Distance Dialing (DDD) or direct dial is a telecommunications term for a network-provided service feature in which a call originator may, without operator assistance, call any other user outside the local calling area. DDD requires more digits in the number dialed than are required for calling within the local area or area code. DDD also extends beyond the boundaries of national public telephone network, in which case it is called International Direct Dialling or International Direct Distance Dialing (IDDD).

DDD is a North American Numbering Plan term considered obsolete since completing a call in any manner other than direct dialing became rare. In the United Kingdom and other parts of the Commonwealth of Nations, the equivalent terms are or were "STD", for subscriber trunk dialling, and "ISTD" for international subscriber trunk dialling.



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:

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