area codearea code
- A three-digit number that is assigned to a geographical area in the United States, Canada, and the Caribbean, used before a seven-digit telephone number when placing a call to, and sometimes from within, that area.
- A similar number of varying length assigned to geographic areas in other parts of the world.
(plural area codes)
- A prefix appended to a telephone number indicating the geographical area.
area code - Computer Definition
Also known as the Numbering Plan Area (NPA). In the North American Numbering Plan (NANP), the three-digit number that corresponds to a geographic area within the area loosely defined as North America.The NPA follows the pattern NXX, with N indicating that only digits 2 9 are allowed, as 0 or 1 would confuse the network, and X indicating that any digit is allowed.The area code originally was used only when a call crossed an area code boundary. In such a case, the dialing sequence is 1.NNX.NNX.xxxx. the 1+ identified the call as long distance and triggered the involvement of an interexchange carrier.Where overlay area codes have been implemented, however, it is necessary to dial a full 10-digit number (NNX.NNX. xxxx) within a geographic area.Also, cellular networks treat area codes differently in terms of dialing pattern and rating. Cellular networks do not require 1+ dialing, and generally bill only for airtime, regardless of whether calls are local or long distance in nature. As a great many individuals subscribe exclusively to cellular service, area codes largely have lost their significance to those users in terms of calling costs, and many of them retain their old telephone numbers even when permanently moving their residences across area code boundaries. See also NANP, NPA, and overlay area code.