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A numbering plan area with multiple area codes is called an overlay. Area codes are also assigned for non-geographic purposes. The rules for numbering NPAs do not permit the digits 0 and 1 in the leading position. [1] Area codes with two identical trailing digits are easily recognizable codes (ERC).
Numbering plan area code The first NXX block is the numbering plan area code. When the second and third digits are the same, the code is an easily recognizable code (ERC). ERCs designate special services; e.g., 800 for toll-free service. The NANP is not assigning area codes with 9 as the second digit. [37]
A closed numbering plan, as found in North America, features fixed-length area codes and local numbers, while an open numbering plan has a variance in the length of the area code, local number, or both of a telephone number assigned to a subscriber line. The latter type developed predominantly in Europe.
The largest telephone numbering plan in North American is the North American Numbering Plan (NANP), serving 25 regions or countries. Other countries maintain an autonomous numbering plan with distinct country codes within the international E.164 specifications by the International Telecommunication Union. Original North American area codes
This is a list of future area codes in the North American Numbering Plan (NANP) that are in the planning stages for relief of central office code exhaustion in the given numbering plan areas (NPAs). The dates are subject to change during implementation as published in the official NANP Administrator Planning Letters.
The North American Numbering Plan is based on a ten-digit telephone number assigned to each telephone in the telephone network. The number is composed of the three-digit numbering plan area code, a three-digit central office code, and a four-digit station or line number. Certain rules govern the numerical format of each part.
An area code overlay is a numbering plan area (NPA) in the North American Numbering Plan (NANP) that has multiple area codes assigned. Overlay complexes are used to add central office prefixes in an NPA to increase the number of available telephone numbers. [1]
In telecommunications, an area code overlay complex is a telephone numbering plan that assigns multiple area codes to the same geographic numbering plan area (NPA). Area code overlays are implemented in territories of the North American Numbering Plan (NANP) to mitigate exhaustion of central office codes in growth areas. The method has been in ...