NANP (North American Numbering Plan)

NANP (North American Numbering Plan) is an integrated telephone numbering plan serving 20 North American countries that share its resources and are in the +1 country code. 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 NXX-NXX-XXXX where N is any digit from 2 through 9 and X is any digit from 0 through 9.

NANPA website