What the Terms "NPA" and "NXX" Mean


Chase Greiser


When ordering or porting telephone numbers, you may hear the terms “NPA” and “NXX” thrown around a lot, as these are standard industry terms.

NPA: This stands for Numbering Plan Area. You probably know it as the area code, the three-digit number that identifies the telephone service region.  You’ll see NPA and area code used interchangeably in our portals and training videos.
  While the Area Code identifies the telephone service region, it’s possible for a single NPA to be present in more than one rate center.
  For example:  The 305 area code in Florida is present in the following rate centers: Keys, Miami, Homestead, North Dade, and Perrine.  If you order a number in NPA 305, you can get a telephone number in any of those rate centers.
NXX: This is the three-digit code that forms the second part of a 10-digit telephone number.  The NXX is also known as the “central office code” or “exchange”.
  For example: if you had the phone number 555-101-1234 the NXX would be 101.


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