POTS Country Codes

Q: How was the country code system developed?

A: In the early 1960s, a global numbering plan was devised so that the various national telephone systems can be linked; this used country codes of one to three digits in length, assigned according to geographic regions on the Earth. In fact, the system was developed from a numbering plan devised in Europe. International Telecommunications Union (ITU) documents from that time showed a numbering plan of two-digit country codes covering Europe and the Mediterranean Basin countries and even described at that time the overseas access codes to be used in various countries (France 19, UK 010 - most of these codes are still in use today). Many country codes from that original numbering plan were used in the worldwide plan such as France 33, UK 44 although many codes had to be renumbered for the new worldwide plan.

The world numbering zones (with initial country code digits) are:

• 1 North America
• 2 Africa
• 3 and 4 Europe
• 5 South/Latin America (includes Mexico)
• 6 South Pacific countries, Oceana (eg. Australia)
• 7 Commonwealth of Independent States (former USSR)
• 8 East Asia (eg. Japan, China), plus Marisat/Inmarsat
• 9 West & South Asia, Middle East (eg. India, Saudi Arabia)

There are a few anomalies to the zoning; St Pierre & Miquelon, a French territory near the Canadian province of Newfoundland, was issued a country code in zone 5 (country code 508), since North America already has the country code 1, and there were no codes available in zones 3 or 4 (at the time of original assignment). There was room in world zone 5 for the code. Similarly, Greenland (country code 299) could not be fit into the European zones, thus 299 was a code that was available from a nearby zone.

The TELECOM Digest Archives has country code listings, including a detailed set which indicates area/STD codes used within country codes as they would be dialed in international dialing (excluding domestic inter-regional prefix digits).

ITU-T Rec.X.121 is a specifiction of a numbering system for geographical areas which is used in the X.25 network specification. ftp://ftp.isi.edu/in-notes/rfc1236.txt details the mapping of IP address to X.25 addresses (X.121)

See also:

• The International Telecommunications Union (ITU) is the global organisation responsible for telecommunications standards, including the assignment of telephone country codes ITU-T Rec. X. 121. Their Operational Bulletin lists changes to national telephone numbering formats in the "Telephone Service" chapter. However, current editions of the Bulletin are only available on the paying service, and not available for general web access
• http://www.att.com/traveler/tools/codes.html basic
• http://csg.sprint.com/ssi/intl_codes.html basic
• http://www.the-acr.com/codes/cntrycd.htm
• https://www.callersmart.com/articles/8/International-Dial-Code-Directory
• http://www.lincmad.com/countrycodes.html
• http://www.interocitor.net/wtng tons of data, excellent notes
• http://www.cs.ucl.ac.uk/misc/intl_codes.html with ring characteristics (old)

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