Number pooling
Encyclopedia
Number pooling is a method of reallocating telephony
numbering space in the North American Numbering Plan
, primarily in growth areas in the United States
.
Originally, in North America, individual telephone exchanges were assigned entire individual prefixes, with all the 10,000 possible numbers (0000 to 9999) having that prefix being available (and only available) to that exchange. ("Prefix", "NXX", and "exchange" are synonymous terms in NANP telephony.) Typically, one exchange served one municipality
(or rarely, groups of closely associated municipalities). As the growth of an area led to increased demands for phone numbers, more prefixes would be added.
Along with the advent of competition among telephone carrier
s, as well as mobile telephone providers, each individual carrier serving a given municipality required its own prefixes. This began to put pressure on the prefixes available within high-growth and high-competition areas, and led to a rapid increase in the introduction of new area codes.
By the early 1990s, the NANPA was forced to change the format rules to increase the number of valid area codes. Previously, all area codes had 0 or 1 as their second (middle) digit; the rule change allowed any digit except 9 as the second digit.
However, public resistance to the introduction of new area codes, even overlay plan
s which allowed customers to keep their existing numbers (as opposed to split plan
s where the area code of existing numbers changes), prompted the FCC
and state telecommunications commissions to introduce and encourage the allocation of number space in smaller blocks of 1,000 numbers, with each block consisting of a prefix and the first digit after the prefix. Local exchange routing databases now include a "block ID" to indicate the ownership of the specific sub-blocks within a prefix.
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
numbering space in the North American Numbering Plan
North American Numbering Plan
The North American Numbering Plan is an integrated telephone numbering plan administered by Neustar which encompasses 24 countries and territories, including the United States and its territories, Canada, Bermuda, and 16 nations of the Caribbean...
, primarily in growth areas in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Originally, in North America, individual telephone exchanges were assigned entire individual prefixes, with all the 10,000 possible numbers (0000 to 9999) having that prefix being available (and only available) to that exchange. ("Prefix", "NXX", and "exchange" are synonymous terms in NANP telephony.) Typically, one exchange served one municipality
Municipality
A municipality is essentially an urban administrative division having corporate status and usually powers of self-government. It can also be used to mean the governing body of a municipality. A municipality is a general-purpose administrative subdivision, as opposed to a special-purpose district...
(or rarely, groups of closely associated municipalities). As the growth of an area led to increased demands for phone numbers, more prefixes would be added.
Along with the advent of competition among telephone carrier
Common carrier
A common carrier in common-law countries is a person or company that transports goods or people for any person or company and that is responsible for any possible loss of the goods during transport...
s, as well as mobile telephone providers, each individual carrier serving a given municipality required its own prefixes. This began to put pressure on the prefixes available within high-growth and high-competition areas, and led to a rapid increase in the introduction of new area codes.
By the early 1990s, the NANPA was forced to change the format rules to increase the number of valid area codes. Previously, all area codes had 0 or 1 as their second (middle) digit; the rule change allowed any digit except 9 as the second digit.
However, public resistance to the introduction of new area codes, even overlay plan
Overlay plan
In telephony, especially in North America, an overlay plan is the practice of introducing a new area code by applying it onto a geographic area that is already occupied by one or more existing area codes, resulting in two area codes serving the same area.- Methodology :Prior to the introduction of...
s which allowed customers to keep their existing numbers (as opposed to split plan
Split plan
In telephony, a split plan is the practice of introducing a new area code by dividing an existing area code's territory and applying the new area code to one of the resulting divisions, replacing the existing area code within that section....
s where the area code of existing numbers changes), prompted the FCC
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
and state telecommunications commissions to introduce and encourage the allocation of number space in smaller blocks of 1,000 numbers, with each block consisting of a prefix and the first digit after the prefix. Local exchange routing databases now include a "block ID" to indicate the ownership of the specific sub-blocks within a prefix.
See also
- Area Code
- Ten-digit dialing
- Local Exchange Routing Guide
- Numbering plan area