This page contains the Federal Communications Commission regulations
relating to telephone numbering, excerpted from the Code of Federal
Regulations, Title 47, Volume 3, Part 52, Subpart B (pages 52-55),
revised as of October 1, 1997, with some formatting added. While
the text displayed below is believed correct, LincMad Consulting
provides no warranty.
Area code or numbering plan area (NPA). The term “area code
or numbering plan area” refers to the first three digits (NXX) of a
ten-digit telephone number in the form NXX-NXX-XXXX, where N represents
any one of the numbers 2 through 9 and X represents any one of the numbers
0 through 9.
Area code relief. The term “area code relief” refers
to the process by which central office codes are made available when there
are few or no unassigned central office codes remaining in an existing
area code and a new area code is introduced.
Central office (CO) code. The term “central office code”
refers to the second three digits (NXX) of a ten-digit telephone number in
the form NXX-NXX-XXXX, where N represents any one of the numbers 2 through 9
and X represents any one of the numbers 0 through 9.
Central office (CO) code administrator. The term
“central office code administrator” refers to the entity
or entities responsible for managing central office codes in each
North American Numbering Plan Administrator (NANPA). The term
“North American Numbering Plan Administrator” refers to the
entity or entities responsible for managing the NANP.
Sec. 52.9 General requirements.
To ensure that telecommunications numbers are made available on an
equitable basis, the administration of telecommunications numbers shall,
in addition to the specific requirements set forth in this subpart:
Facilitate entry into the telecommunications marketplace by making
telecommunications numbering resources available on an efficient,
timely basis to telecommunications carriers;
Not unduly favor or disfavor any particular telecommunications
industry segment or group of telecommunications consumers; and
Not unduly favor one telecommunications technology over another.
If the Commission delegates any telecommunications numbering
administration functions to any State or other entity pursuant to
47 U.S.C. 251(e)(1), such State or entity
shall perform these functions in a manner consistent with this part.
Sec. 52.11 North American Numbering Council.
The duties of the North American Numbering Council (NANC), may
include, but are not limited to:
Advising the Commission on policy matters relating to the administration
of the NANP in the United States;
Making recommendations, reached through consensus, that foster
efficient and impartial number administration;
Initially resolving disputes, through consensus, pertaining to
number administration in the United States;
Recommending to the Commission an appropriate entity to serve
as the NANPA;
Recommending to the Commission an appropriate mechanism for recovering
the costs of NANP administration in the United States, consistent
with Sec. 52.17;
Carrying out the duties described in
[Subpart C — Number Portability]; and
Carrying out this part as directed by the Commission.
Sec. 52.13 North American Numbering Plan
The North American Numbering Plan Administrator (NANPA) shall
be an independent and impartial non-government entity.
The duties of the NANPA shall include, but are not limited to:
Ensuring that the interests of all NANP member countries are considered;
Processing number assignment applications associated with, but
not limited to: area codes, N11 codes, carrier identification
codes (CICs), “500” central office codes, “900”
central office codes, “456” central office codes[*],
Signalling System 7 network codes, and Automatic Number Identification
Integration Integers (ANI II);
Assigning the numbers and codes described in paragraph (b)(2)
of this section;
Maintaining and monitoring administrative number databases;
Assuming additional telecommunications number administration activities,
as assigned; and
Ensuring that any action taken with respect to number administration
is consistent with this part.
Sec. 52.15 Central Office Code Administration.
Central Office Code Administration shall be performed by the NANPA,
or another entity or entities, as designated by the Commission.
Duties of the entity or entities performing central office code
administration may include, but are not limited to:
Processing central office code assignment applications and assigning
such codes in a manner that is consistent with this part;
Accessing and maintaining central office code assignment databases;
Contributing to the CO Code Use Survey (COCUS), an annual survey
that describes the present and projected use of CO codes for each
NPA in the NANP; [[Page 54]]
Monitoring the use of central office codes within each area code
and forecasting the date by which all central office codes within
that area code will be assigned; and
Planning for and initiating area code relief, consistent with
Any telecommunications carrier performing central office code
Shall not charge fees for the assignment or use of central office
codes to other telecommunications carriers, including paging and
CMRS providers, unless the telecommunications carrier assigning
the central office code charges one uniform fee for all carriers,
including itself and its affiliates; and
Shall, consistent with this subpart, apply identical standards
and procedures for processing all central office code assignment
requests, and for assigning such codes, regardless of the identity
of the telecommunications carrier making the request.
Sec. 52.17 Costs of Number Administration.
All telecommunications carriers in the United States shall contribute
on a competitively neutral basis to meet the costs of establishing
For each telecommunications carrier, such contributions shall
be based on the gross revenues from the provision of its telecommunications
The contributions in paragraph (a) of this section shall be based
on each contributor’s gross revenues from its provision of telecommunications
services reduced by all payments for telecommunications services
and facilities that have been paid to other telecommunications
Sec. 52.19 Area Code Relief.
State commissions may resolve matters involving the introduction
of new area codes within their states. Such matters may include,
but are not limited to: Directing whether area code relief will
take the form of a geographic split, an overlay area code, or
a boundary realignment; establishing new area code boundaries;
establishing necessary dates for the implementation of area code
relief plans; and directing public education and notification
efforts regarding area code changes.
State commissions may perform any or all functions related to
initiation and development of area code relief plans, so long
as they act consistently with the guidelines enumerated in this
part, and subject to paragraph (b)(2) of this section. For the
purposes of this paragraph, initiation and development of area
code relief planning encompasses all functions related to the
implementation of new area codes that were performed by central
office code administrators prior to February 8, 1996. Such functions
may include: declaring that the area code relief planning process
should begin; convening and conducting meetings to which the
telecommunications industry and the public are invited on area code
relief for a particular area code; and developing the details of a
proposed area code relief plan or plans.
The entity or entities designated by the Commission to serve as
central office code administrator(s) shall initiate and develop
area code relief plans for each area code in each state that has
not notified such entity or entities, pursuant to paragraph (b)(2)
of this section, that the state will handle such functions.
Pursuant to paragraph (b)(1) of this section, a state commission
must notify the entity or entities designated by the Commission
to serve as central office code administrator(s) for its state
that such state commission intends to perform matters related
to initiation and development of area code relief planning efforts
in its state. Notification shall be written and shall include
a description of the specific functions the state commission intends
to perform. Where the NANP Administrator serves as the central
office code administrator, such notification must be made within
120 days of the selection of the NANP Administrator.
New area codes may be introduced through the use of:
A geographic area code split, which
occurs when the geographic area served by an area code in which there
are few or no central office codes left [[Page 55]]
for assignment is split into two or more geographic parts;
An area code boundary realignment,
which occurs when the boundary lines between two adjacent area
codes are shifted to allow the transfer of some central office
codes from an area code for which central office codes remain
unassigned to an area code for which few or no central office
codes are left for assignment; or
An area code overlay, which occurs
when a new area code is introduced to serve the same geographic area as
an existing area code, subject to the following conditions:
No area code overlay may be implemented unless all central office
codes in the new overlay area code are assigned to those entities
requesting assignment on a first-come, first-serve basis, regardless
of the identity of, technology used by, or type of service provided
by that entity. No group of telecommunications carriers shall
be excluded from assignment of central office codes in the existing
area code, or be assigned such codes only from the overlay area
code, based solely on that group’s provision of a specific type
of telecommunications service or use of a particular technology;
No area code overlay may be implemented unless there exists, at
the time of implementation, mandatory ten-digit dialing for every
telephone call within and between all area codes in the geographic
area covered by the overlay area code; and
No area code overlay may be implemented unless every telecommunications
carrier, including CMRS providers, authorized to provide telephone
exchange service, exchange access, or paging service in that NPA
90 days before introduction of the new overlay area code, is assigned
during that 90 day period at least one central office code in
the existing area code.
United States Code
– Telegraphs, Telephones, and Radiotelegraphs Chapter 5
– Wire or Radio Communication Subchapter II
– Common Carriers
Part II - Development of Competitive Markets
Sec. 251. Interconnection
(e) Numbering administration
(1) Commission authority and jurisdiction
The Commission shall create or designate one or more impartial
entities to administer telecommunications numbering and to make
such numbers available on an equitable basis. The Commission shall
have exclusive jurisdiction over those portions of the North American
Numbering Plan that pertain to the United States. Nothing in this
paragraph shall preclude the Commission from delegating to State
commissions or other entities all or any portion of such jurisdiction.
[For an authoritative copy of this statute, please consult the
U.S. House of Representatives, U.S. Code on the web,
47 USC 251.]
* Note: The 456 NPA has been retired as of 2017,
and will be available for reassignment as a general-purpose NPA in 2023.
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Last updated 1998-07-25; minor footnote added 2017-11-27.
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