International Direct Dialling

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International Direct Dialling (IDD) is an international telephone call dialled by the caller rather than going via an operator. The term International Subscriber Dialling (ISD) was used in the United Kingdom and Australia until the terminology was changed to International Direct Dialling. Since late in the 20th century, most international calls are direct dialed.

International calls are made by dialling the international call prefix for the country one is in, followed by the country calling code for the country one wishes to call, then the phone number within that country. When phone numbers are published for use abroad, they typically include the country calling code, but replace the international call prefix with "+" to signify that the caller should use the prefix appropriate for their country.

[edit] See also

• Subscriber trunk dialling