North America Numbering Plan
- Telephones in North America usually consist of ten digits, in the following format: NPA-NXX-XXXX. NPA is the area code, NXX is the exchange, and XXXX the line number. N can be any digit between 2 and 9, P can be any digit except 9, and X can be any digit between 0 and 9. Its abbreviation is NANP.