The North American Numbering Plan Administration, NANPA, is the group responsible for assigning blocks of telephone numbers to individual telephone companies. You can download a table of the actual assignments at the NANPA website. Another website, Telcodata.us, provides a simple look-up service. Either way, matching a phone number to the telephone company that owns it is a straightforward process. The text file is zipped (compressed). Most computers will automatically unzip the file without any need for user action. Writer Bio
