International Direct Dialling
(IDD) is the term used to describe an international telephone call
dialled by the caller rather than going via an operator
(see list of country calling codes
). The term International Subscriber Dialling
(ISD) was used in the United Kingdom
until the terminology was changed to International Direct Dialling.
Up to the late 1990s, international outgoing calls in India
were expensive so most landline subscribers did not opt for this facility. After reforms in the telecom sector initiated by the Government of India
in 2000, the ISD facility has become ubiquitous. A public phone booth marked ISD
has the facility to make international phone calls.
+List of international call prefixes