Numbering Plan Area NPA

NANP · also called area code

The three-digit area code that begins a North American telephone number (the "NPA" in NPA-NXX-XXXX).

A Numbering Plan Area (NPA) — commonly called an area code — is the first three digits of a ten-digit NANP telephone number. It identifies a numbering area, which may be a geographic region (for example, a metropolitan area or part of a state or province) or a non-geographic service such as toll-free.

NPAs take the form [2-9][0-9][0-9] — the first digit is 2–9. Codes with a middle digit of 9 (N9X) are held in reserve for a future expansion of the plan and are not currently assigned. When an area code approaches exhaustion, it is given relief — usually an overlay or, historically, a split.

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.

An area code identifies a numbering area, not a city. Its boundaries follow rate-center geography, not municipal lines — and because of number portability, a number's area code does not reliably indicate where the caller physically is.

See it in live dataNumberResearch

Every area code page on NumberResearch shows this in practice — assigned prefixes, thousands-block breakdown and exhaust forecast. For example: area code 626 ↗.