Audio response unit

In telecommunication, an audio response unit (ARU) is a device that provides synthesized voice responses to dual-tone multifrequency signaling input by processing calls based on (a) the call-originator input, (b) information received from a host data base, and (c) information in the incoming call, such as the time of day.

Note: ARUs are used to increase the number of information calls handled and to provide consistent quality in information retrieval.

Source: from Federal Standard 1037C