A toll service that permits customers to place their own long distance calls without the aid of an operator.

A service that lets a user (personally or via modem) dial long distance telephone numbers without operator assistance.

Any switched telecommunication service (like 1+, 0++, etc.) that allows a call originator to place long distance calls directly to telephones outside the local service area without an operator.

A telephone system which enables users to directly dial telephone numbers outside the user's local exchange area without the aid of an operator.

Direct Distance Dialing (DDD) or direct dial is a telecommunications term for 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 or area code. DDD also extends beyond the boundaries of national public telephone network, in which case it is called International Direct Distance Dialing (IDDD).