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A common numbering format used in the North American Numbering Plan (NANP) to represent telephone numbers. Here’s what each part means:

NPA (Numbering Plan Area): This is the area code, which is the first three digits of a ten-digit phone number. The NPA corresponds to a specific geographic region within the NANP, which includes the United States, Canada, certain U.S. territories, and a few Caribbean countries.

NXX: This refers to the central office code, which is the next three digits of a ten-digit phone number. The NXX, also known as the exchange, identifies the specific switch (central office) serving a particular area.

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