ATIS 0300070(2020-10)

These guidelines identify Service Provider (SP) responsibilities with respect to individual telephone numbers in the 10-digit NANP number format (NPA-NXX-XXXX) within existing geographic central office (NXX) codes administered by the North American Numbering Plan Administrator (NANPA) and the Pooling Administrator (PA). It contains guidelines for the administration of Aging Numbers, Reserved Numbers, and Sequential Number Assignment.