High Quality Content by WIKIPEDIA articles! With the development of computerized telephone dialing systems, many telephone calls which previously required a live operator can be placed automatically by the calling party without additional human intervention. Before the advent of automatic exchanges, an operator's assistance was required for anything other than calling telephones across a shared party line. Callers spoke to an operator at a Central Office who then connected a cord to the proper circuit in order to complete the call. Being in complete control of the call, the operator was in a position to listen to private conversations. Direct Dial (DDD) systems were developed in the 1920s to reduce labor costs as usage increased, and to ensure privacy to the customer. As phone systems became more sophisticated, this sort of direct intervention by the telephone operator was needed less and less.

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