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Public numbering data

US Telephone Prefix Lookup

Check an area code and the next three digits against NANPA’s assigned central-office codes.

US telephone prefix lookup

Search NANPA’s US central-office code assignments. The listed company and rate center describe an assignment; number portability means they cannot identify the current carrier, subscriber, or caller.

The area-code file loads when you search. The three-digit prefix stays in your browser.

What does a prefix show?

In a +1 number, the NPA is the area code and the NXX is the next three-digit prefix. This report covers assigned US prefixes and lists the original assignment company and rate center. Number portability and reassignment mean it cannot prove a number is active, who owns it, or which carrier serves it today.

Check a Canadian prefix.

Source: NANPA Central Office Code Assignment Records, updated 2026-09-29.