Science Fair Project Encyclopedia
Direct distance dialing
In telecommunication, direct distance dialing (DDD) is a network-provided service feature in which a call originator may, without operator assistance, call any other user outside the local calling area. DDD requires more digits in the number dialed than are required for calling within the local area. DDD also extends beyond the boundaries of national public telephone networks.
Direct distance dialing (DDD) is a North American Numbering Plan term, and considered obsolete as calls are now rarely completed in any other manner. In the UK and other parts of the British Commonwealth, the equivalent term is or was "STD", for subscriber trunk dialling.
Source: partly from Federal Standard 1037C and from MIL-STD-188
Last updated: 08-11-2005 08:00:31
10-26-2009 08:16:03
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details