Data sources and method

Every number on this site comes from public records. Nothing is user-submitted and we do not publish personal data about phone number owners.

Sources

• NANPA area code report: which area codes are in service, when they started, overlays, splits, time zones.
• NANPA central office code assignments (utilized codes, all states): every assigned prefix with its carrier and rate center.
• NANPA NPA exhaust projections, 2026 first-half forecast: when each area code is expected to run out of prefixes.
• US Census Bureau: 2025 Gazetteer place coordinates, 2025 population estimates for incorporated places, ACS 2019–2023 for census-designated places.

How cities are matched

NANPA records prefixes by rate center, an abbreviated exchange name of up to 10 letters such as “SUTTER CRK”. We match each rate center to the Census place with the same name in the same state. Some exchanges cover a whole county or suburban zone (Nassau County, Northern Virginia, the Twin Cities); their numbers are assigned to every place in those counties. Cities without their own rate center get the area codes of the nearest matched exchange within 25 km.

About 83% of rate centers match. Unmatched ones are left out rather than guessed. An area code is listed for a city only when it holds at least 10% of that city's prefixes, or when it is a newer overlay of a code that does, so a couple of stray prefixes do not put a city under the wrong code.

Spotted a mistake? Write to us and we will check it against the NANPA records.

Carrier types

Mobile, VoIP/cable and landline shares are classified from the carrier name on the original prefix assignment. Numbers are often ported between carriers afterwards, so treat the split as an approximation of who the area code's numbers were issued to.