The North American Numbering Plan (NANP) is an integrated telephone numbering
plan serving 19 North American countries that share its resources.
These countries include the United States and its territories, Canada,
Bermuda, Anguilla, Antigua & Barbuda, the Bahamas, Barbados, the British Virgin
Islands, the Cayman Islands, Dominica, the Dominican Republic, Grenada, Jamaica,
Montserrat, St. Kitts and Nevis, St. Lucia, St. Vincent and the Grenadines,
Trinidad and Tobago, and Turks & Caicos.
Regulatory authorities in each participating country have plenary authority over
numbering resources but the participating countries share numbering resources
AT&T developed the North American Numbering Plan in 1947 to simplify and
facilitate direct dialing of long distance calls. Implementation of the plan
began in 1951.
The International Telecommunications Union (ITU) assigned country code "1" to
the NANP area. The NANP conforms with ITU Recommendation E.164, the
international standard for telephone numbering plans.
NANP numbers are ten-digit numbers consisting of a three-digit Numbering Plan
Area (NPA) code, commonly called an area code, followed by a seven-digit local
number. The format is usually represented as
where N is any digit from 2 through 9 and X is any digit from 0 through 9.