1. A defined geographic area identified by a unique three-digit code used in the North American Number Plan Area. [T1.207-1998] [T1.209-1998] Note 1: Defined geographic area could mean the entire area encompassed by the North American Numbering Plan Area (for 800, 888, 877 codes, etc.). Note 2: By virtue of the overlay concept deployed in some states, there may be two (or more) NPAs assigned to the same defined geographic area. 2. Numbering Plan Area, also called area code. An NPA is the 3-digit code that occupies the A, B, and C positions in the 10-digit NANP format that applies throughout the NANP Area. NPAs are of the form NXX, where N represents the digits 2-9 and X represents any digit 0-9. In the NANP, NPAs are classified as either geographic or non-geographic.
a) Geographic NPAs are NPAs which correspond to discrete geographic areas within the NANP Area.
b) Non-geographic NPAs are NPAs that do not correspond to discrete geographic areas, but which are instead assigned for services with attributes, functionalities, or requirements that transcend specific geographic boundaries. The common examples are NPAs in the N00 format, e.g., 800.~