North American Numbering Plan NANP

NANP — 25 numbering regions across 20 countries (US, Canada, Caribbean/Atlantic nations) · also called NANP, country code 1

The telephone numbering plan shared by the United States, Canada and 18 other countries and territories under country code 1 — 25 numbering regions in 20 countries.

The North American Numbering Plan (NANP) is an integrated numbering plan for the public switched telephone networks of 20 countries — the United States, Canada and 18 Caribbean and Atlantic nations and territories — organized as 25 numbering regions, all reachable under international country code 1. It defines telephone numbers as a three-digit area code (NPA), a three-digit central-office code (NXX) and a four-digit line number: the familiar NPA-NXX-XXXX form.

The plan is administered under the direction of the U.S. Federal Communications Commission and the Canadian Radio-television and Telecommunications Commission, with day-to-day number-resource administration performed by the North American Numbering Plan Administrator (NANPA) and, in Canada, the Canadian Numbering Administrator.

A number is country code + area code (NPA) + prefix (NXX) + a four-digit line number. The first digit of the four-digit line number — the seventh digit of the 10-digit national number, not counting the country code +1 — marks which pooled thousands-block of 1,000 numbers it belongs to.

Common misconception.

The NANP is not the same as "the US phone system." It also covers Canada and 18 other countries and territories such as Jamaica, the Bahamas and Puerto Rico — each with its own area codes but all dialable under country code 1.