The time interval between the instant of occurrence of a specified input condition to a system and the instant of completion of a specified operation. In communications, computer, and information processing systems, the time interval between the instant a request for service is received from a user and the instant of final release of all facilities by the user or either of two users. In communications systems conference calls, the time interval between the instant a request for service is received from one of a group of concurrent users and the instant all but one of the users have released all facilities.

Productive time available after Down Time Losses are subtracted. Operating Time increases as Down Time Losses are reduced.

The time required for dialing a call, waiting for the connection to be established, coordinating the transmission with the personnel or equipment at the receiving end, and disconnecting after the transmission.

(relay) (device/circuit) The time interval between satisfaction of the specified input conditions and the occurrence of the specified operation.