The telephone numbering plan that encompasses twenty-five distinct regions in twenty countries primarily in North America, including the Caribbean. Some North American countries, most notably Mexico, do not participate in the NANP. The NANP was originally devised in the 1940s by AT&T for the Bell System and independent telephone operators in North America to unify the diverse local numbering plans that had been established in the preceding decades. AT&T continued to administer the numbering plan until the breakup of the Bell System.

The NANP number format may be summarized in the notation NPA-NXX-xxxx. The NANP divides the territories of its members into numbering plan areas (NPAs) which are encoded numerically with a three-digit telephone number prefix, commonly called the area code. The NXX, the next set of three digits, is the Central Office Exchange code. Finally, the xxxx is the subscriber line number.