International call prefix

An international call prefix, international dial-out code or international direct dial code (IDD code) is a trunk prefix that indicates an international phone call. In the dialling sequence, the prefix precedes the country calling code (and, further, the carrier code, if any, and the destination telephone number).

The international call prefix is part of the telephone numbering plan of every country.


The International Telecommunication Union (ITU) recommends the sequence 00 as a standard for an international call prefix, and this has been implemented by the majority of countries.[1] A significant number of countries, however, use 011 as the international call prefix – mainly countries that follow the North American Numbering Plan. Certain post-Soviet states continue to use 810 which was the universal IDD code across the Soviet Union. Other prefixes (000, 001, 0011, 119, etc.) are also in use in a small number of countries.

Some countries require that the 00 prefix is followed immediately by the so-called carrier selection code, i.e., a numeric code that routes the call via a specific provider of international connectivity. Other countries may require that any carrier selection codes precede the international call prefix.

Some countries also offer simplified dialling arrangements for calls to neighbouring countries, usually by removing the need of dialling an international call prefix and the country code.[2]

To avoid confusion especially in international context, a plus sign (+) is often used as a graphic symbol of the international access code; it informs the caller to replace it with the prefix code appropriate for their country.[3] Additionally, the GSM mobile telephony standard allows the use of the plus sign in place of the international call prefix; the mobile operator then automatically converts the plus sign to the correct international prefix, depending on the location where the phone is being used. This enables callers to use the same stored number when calling from any country.


Calling +64 3 477 4000, which is the number of Dunedin City Council in New Zealand (country code: 64), from outside New Zealand:

Call placed from IDD prefix Number dialled
Countries that follow ITU recommendation (incl. European Union, United Kingdom, China, India)0000 64 3 477 4000
Kenya, Singapore, Tanzania, Uganda000000 64 3 477 4000
Guyana, Mongolia001001 64 3 477 4000
Australia00110011 64 3 477 4000
Nigeria009009 64 3 477 4000
Japan010010 64 3 477 4000
Countries that follow NANP (incl. United States, Canada)011011 64 3 477 4000
Cuba119119 64 3 477 4000
Belarus, Kazakhstan, Russia, Tajikistan, Turkmenistan810810 64 3 477 4000
Systems that allow the plus symbol (+), e.g. mobile networksauto-generated+ 64 3 477 4000

See alsoEdit


  1. ^ "E.164 – 12" (PDF). International Telecommunication Union (ITU-T). Archived from the original on 2019-06-20. Retrieved 2015-08-19. See page 22 for a list of exceptions
  2. ^ "International landline dialing prefix by country". T-Mobile. Archived from the original on 2005-11-26.
  3. ^ "E.123 - 7.1" (PDF). International Telecommunication Union (ITU-T). Archived from the original on 2012-10-12. Retrieved 2009-05-28. See page 9