!!! Overview
[{$pagename}] ([National Destination Code] or often referred to as [Area Code] or city code) is a numeric routing [Code] within a specific [Telephone Numbering Plan] which has been divided into regional service areas.


[{$pagename}] is often part of a [Telephone Numbering Plan] which subdivide their territory of service into geographic regions designated by a prefix which is a set of digits forming the most-significant part of the dialing sequence to reach a telephone subscriber.

[{$pagename}] concept was first developed for Operator Toll Dialing of the Bell System in the early [1940s], which preceded the [North American Numbering Plan] ([NANP]) of [1947|Year 1947]. The North American Numbering Plan (NANP) divided the North American service territories into [Number Plan Areas] (NPAs), and assigned to each [NPA] a unique numerical prefix, the [Number Plan Area] code, which became known in short-form as [Area Code]. 

[{$pagename}] is prefixed to each telephone number issued in its service area.

!! [{$pagename}] [Example]
[{$pagename}] for [North American Numbering Plan] the Allowed ranges for [{$pagename}] for the [National Destination Code] ([Area Codes]) are: 
* (2–9) for the first digit
* (0-9) for the second 
* (0-9) third digit

When the second and third digits of a [National Destination Code] are the same, that code is called an [Easily Recognizable Code] ([ERC]) which designate special services; e.g., 888 or 800 for toll-free service. 

[North American Numbering Plan] is not assigning area codes with 9 as the second digit.



!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
----
* [#1] - [555 Line Numbers|https://www.nationalnanpa.com/number_resource_info/555_numbers.html|target='_blank'] - based on information obtained 2019-08-15