US telephone prefix ==> "NPA" A/K/A "North American Numbering Plan"

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Definition: http://www.probertencyclopaedia.com/N14.HTM

NPA - Abbreviation for "Numbering Plan Area" (area code)

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From: http://sd.wareonearth.com/~phil/npanxx/

North American Numbering Plan, NPA/NXX's

As of April 1999, there were 105291 NPA/NXX's (area code plus exchanges)
registered for use in the USA and Canada. These prefixes are served by
"central offices" located at some 24644 "wire centers". It is at these wire
centers that "local loops" to customers are terminated and branch circuits
to other offices originate.

Map: http://sd.wareonearth.com/~phil/npanxx/wirecenters.gif

This map shows the distribution of wire centers in the USA and Canada. A
given NPA/NXX pair will map to exactly one of these points. Each of these
points may serve from 1-30 exchanges. The map is a gnomonic projection:
straight lines are great circle paths, angles are true. [Click the image for
a larger map.]

A 3.7 MB April 1999 ascii database of these exchanges and wire centers is
available on line. The format is:

       npa nxx  lat   lng   u st city
       201 200 40.71 074.07 L NJ Jersey City
       201 202 40.85 074.04 W NJ Little Ferry
       201 203 40.79 074.48 W NJ Morristown
       (L and W mean land or wireless use)

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NPA information, including Area codes introduced since 1995
and planned area codes not yet in service:

http://www.nanpa.com/area_codes/

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RF Jim

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