NPANXX refers to the first 6 digits of a standard 10 digit phone number as defined by the The North American Numbering Plan (NANP).
Number Plan Areas (NPA) are commonly refered to as Area Codes. NXX specifies an exchange area within the NPA.
Listed carriers owns at least 50% of all NPANXX numbers in service. Full 10 digit phone numbers may differ from NPANXX carrier due to pooling.
Refer to the glossary for more information.