NASC - 800 / Number Administration and Service Center

The organization that administers the SMS/800 system for the reservation, registration and administration of all North American Toll-Free numbers ( 800,888,877,866 ) for all carriers. ( See 800 Portability, RespOrg and SMS/800 )

Toll Free Telephone
Service ( 800, 888,877, 866 )

NANP - North American Numbering Plan

NAP- Network Access Points

Connection points between different networks.

North American "Area Codes." ( 3 digits: 2-to-9, 0-or-1, 0-to-9. Middle digit to expand soon )

NPA Area Codes, NXX Exchanges and XXXX Line Numbers

The process for assigning 10-digit ( 3+3+4 ) North American telephone numbers ( See NANP )

Area Code / Exchange Routing. Route telephone calls based on the originating ANI NPA-NXX.

NPA Routing

Area Code Routing. Route telephone calls based on the originating ANI NPA ( area code. )

NPA Split

Subdivision of an area code, with the creation of a new area code. This becomes necessary when the amount of telephone numbers in an area code ( NPA ) grows to an excessive number.

NUS

NASC SMS/800 Toll Free Number Search. SMS application used to find available Toll Free 800, 888, 877, 866 numbers and reserve them for up to 60 days.

Toll Free Telephone Service
800 / 888 / 877 / 866 Numbers

NXX

Exchanges ( Also known as Prefixes, or Office Codes) (First 3 digits of a 7-digit phone number). (2-to-9, 0-to-9, 0-to-9) (Digits 4, 5 and 6 in a 10 digit NANP telephone number - NPA-NXX-XXXX).
NXX is the 3 digits following the Area Code ( NPA )