North American Numbering Plan

The North American Numbering Plan (NANP) is an integrated telephone numbering plan of 24 countries and territories: the United States and its territories, Canada, Bermuda, and 16 of the Caribbean countries.

The NANP is a standardized system of numbering plan areas (NPA), which have evolved over time into a system of three-digit area codes and seven-digit telephone numbers. Through this plan, telephone calls can be directed to particular regions of the larger NANP public switched telephone network (PSTN), where they are further routed by the local networks.