What do the terms NPA and NXX mean?

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Chase Greiser

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NPA and NXX are standard industry terms that you may hear thrown around a lot when ordering or porting telephone numbers. 

What is NPA?

NPA stands for Numbering Plan Area. It's often used interchangeably with the area code, which is a three-digit number that identifies the phone 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 phone number in NPA 305, it can be in any of those rate centers.

What is NXX?

NXX, also known as the central office code or exchange, is a three-digit code that forms the second part of a 10-digit phone number.

For example: In the phone number 555-101-1234, the NXX is 101.

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