International direct dialing (IDD) or international subscriber dialling (ISD) is placing an international telephone call that is dialed directly by a telephone subscriber, rather than by a telephone operator.
The term international subscriber dialling was used in the United Kingdom and Australia until the terminology was changed to international direct dialling. Since the late 20th century, most international calls are dialed directly.
Calls are initiated by dialing the international call prefix for the originating country, followed by the country calling code for the destination country, and finally the national telephone number of the destination.
When telephone phone numbers are published for international use, the international access code is omitted, and the number is listed to start with a plus sign (+) followed by the country calling code. The plus sign indicates that the country code follows, and that an access code may have to be dialed in the originating country.
The first transatlantic direct dial telephone call was made by Sally Reed in Dedham, Massachusetts to her penpal, Ann Morsley, in Dedham, Essex, in 1957. It was witnessed by Reed's teacher, Grace Hine, Dedham's former chief telephone operator, Margaret Dooley, and several representatives of New England Telephone and Telegraph Company. In March 1970, the United States introduced a new nationwide system, called International Direct Distance Dialing (IDDD), as an extension of Direct Distance Dialing (DDD) that was inaugurated in 1951 in Englewood, NJ.
referenceEver curious about what that abbreviation stands for? fullforms has got them all listed out for you to explore. Simply,Choose a subject/topic and get started on a self-paced learning journey in a world of fullforms.
Allow To Receive Free Coins Credit 🪙