The numbering planning area (NPA) are the three digit numbers that identify the region of specific localities across North America.
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​Note: Several rate centers, across a locality, can also share the same NPA. A rate center can be found by finding the NPA - NXX of a phone number. For example our office is located in Austin, Texas, the NPAs or Area Codes for Austin are 512 and 737.

Where

For example: (858) 922-1234:

An exhausted NPA refers to the area codes where almost all numbering resources are assigned and the industry has minimal available numbers. The only way to establish more resources within an active NPA's operational area is through an industry overlay.

Overlay: Overlay is an area code that's added to a region already serviced by another area code. Overlays require the industry to switch from ten digit dialing rather than seven - an easy switch for Telnyx because we already operate on 10 digit dialing!

If you’re trying to order new telephone numbers in a desirable area code, you may find there are limited quantities available. In this case, expanding your search with an overlay can be incredibly helpful.

For example: in the year 2010, the New York City area code 212 became exhausted. To provide relief, the industry added 917 and 646 as Overlays, bringing new available numbers to the area. All of these area codes service the same geographic region as 212. More information about relief planning is available here

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Below mentioned is the updated list of Exhausted NPA's: