Overview#

North American Numbering Plan (NANP) is the Telephone Numbering Plan implemented within the United States, United States Territories about 20 Countries in total.

North American Numbering Plan format may be summarized in the notation NPA-NXX-XXXX:

  • Number Plan Area (NPA) - Area Code
  • National Destination Code (NDC) - Central Office (telephone exchange Area Code) - Allowed ranges: 2–9 for the first digit, and 0–9 for both the second and third digits
    • however, in geographic area codes the third digit of the NDC cannot be 1 if the second digit is also 1 as to not interfere with N11 services.
  • Subscriber Number (SN) - is the Unique Identifier for the End-User Phone Number
  • 5XX-NXX codes are in the format 5XX-NXX-XXXX. 5XX-NXX codes, each subsuming a block of 10,000 numbers, are assigned to service providers.
  • 555 line numbers have been returned to the inventory of NANPA resources. The following 555 line numbers remain in use:
    • 555-1212 Directory Assistance National use
    • 555-4334 Assigned National use
  • N9X - The 80 codes in this format, called expansion codes, have been reserved for use during the period when the current 10-digit NANP number format undergoes expansion.
  • 37X and 96X - Two blocks of 10 codes each have been set aside by the INC for unanticipated purposes where it may be important to have a full range of 10 contiguous codes available.
  • 800-855 - numbers are strictly assigned for toll-free use, and the Toll-Free Numbers.
  • 900 - numbers are used for premium services, with the cost of each 900 call is billed to the calling party.

National Destination Code (NDC) when combined with the Subscriber Number (SN) - will constitute the National Significant Number of the international E.164-number for geographic areas.

North American Numbering Plan Administrator holds overall responsibility for the neutral administration of NANP numbering resources, subject to directives from regulatory authorities in the countries that share the NANP. NANPA's responsibilities include assignment of NANP resources, and, in the United States and its United States Territories, coordination of area code relief planning and collection of utilization and forecast data.

NANPA is not a policy-making entity. In making assignment decisions, NANPA follows regulatory directives and industry-developed guidelines. NANPA's responsibilities are defined in Federal Communications Commission (FCC) rules and in comprehensive technical requirements drafted by the telecommunications industry and approved by the FCC.

North American Numbering Plan countries include:

More Information#

There might be more information for this subject on one of the following:

This page (revision-7) was last changed on 29-Nov-2024 16:16 by -jimTop