Telephone Country Code

A telephone country code is a country-specific telephone number prefix for international direct dialing (IDD), a system for reaching telephone service subscribers in foreign areas via international telecommunication networks. Country codes are defined by the International Telecommunication Union (ITU) in ITU-T standards E.123 and E.164.

Country codes constitute the international telephone numbering plan. They are used only when dialing a telephone number in a foreign region other than the caller's. They are dialed before the national telephone number. Typically, the intend of dialing a foreign telephone number, requires at least one additional prefix, the international call prefix which is an exit code from the national numbering plan to the international one. It essentially requests and reserves an international telephone circuit for the call. ITU standards recommend the digit sequence ''00'' for this prefix and most countries comply. The prefix is ''011'' in the countries of the North American Numbering Plan (NANP), while a minority of countries use other prefixes. When printing telephone numbers the requirement of dialing this prefix is indicated by a plus-sign (''+'') in front of a complete international telephone number, per ITU Recommendation E164.

Country codes were originally introduced and termed ''International Codes'' in 1960 by the International Telegraph and Telephone Consultative Committee (C.C.I.T.T.) in the II^nd Plenary Assembly in New Delhi, but have sometimes also been referred to as "country dial-in codes", or historically as "international subscriber dialing" (ISD) codes in the United Kingdom.

A country or region with an autonomous telephone administration must apply for membership in the International Telecommunication Union (ITU) to participate in the international public switched telephone network (PSTN). Country codes are defined by the ITU-T section of the ITU in standards E.123 and E.164.

History

Country codes were first defined in 1960 by the International Telegraph and Telephone Consultative Committee (C.C.I.T.T) in Recommendation E.29 in the ITU Red Book as ''international codes''. This work for the II^nd Plenary Assembly of the C.C.I.T.T. only considered an international numbering plan for Europe, parts of western Asia, and some Mediterranean countries,

In 1964, E.29 was expanded with a global code system of ''world numbering zones'', loosely defined by geographic location.

In the 1968 White Book, the definition of country codes was relegated to ITU Recommendation E.161.

Codes were typically allocated by landmass and then subdivided by the capacity of each network at the time. France, the United Kingdom, the USA and USSR obtained preferential numbers due to their dominance in telecommunications at the time, whilst China was able to ensure that Taiwan was officially unlisted whilst being allocated the code "886".

World numbering zones

The world numbering zones were defined by the C.C.I.T.T. in Recommendation E.29 in 1964. They were generally defined geographically, with exceptions for political and historical alignments. The terminology is largely obsolete.

Zone 1, the North American Numbering Plan (NANP), uses country code ''1'' and a three-digit area code to designate the area served within the United States and its territories, Canada, and much of the Caribbean.

Zone 2 uses two two-digit country codes (20, 27) and seven sets of three-digit codes (21x–26x, 29x), mostly to serve Africa, but also Aruba, Faroe Islands, Greenland and British Indian Ocean Territory.

Zones 3 and 4 use sixteen two-digit codes (30–34, 36, 39–41, 43–49) and four sets of three-digit codes (35x, 37x, 38x, 42x) to serve Europe.

Zone 5 uses eight two-digit codes (51–58) and two sets of three-digit codes (50x, 59x) to serve South and Central America.

Zone 6 uses seven two-digit codes (60–66) and three sets of three-digit codes (67x–69x) to serve Southeast Asia and Oceania.

Zone 7 uses two digits (7x) to determine the area served: Russia or Kazakhstan.

Zone 8 uses four two-digit codes (81, 82, 84, 86) and four sets of three-digit codes (80x, 85x, 87x, 88x) to serve East Asia, South Asia and special services.

Zone 9 uses seven two-digit codes (90–95, 98) and three sets of three-digit codes (96x, 97x, 99x) to serve the Middle East, West Asia, Central Asia, parts of South Asia and Eastern Europe.

See also

*List of telephone country codes
*Country code

References

External links

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{{DEFAULTSORT:Telephone country codes
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International telecommunications
Telecommunications-related introductions in 1960
Telecommunications-related introductions in 1964