a voice response unit includes a silent prompt feature in the form of an intentional delay inserted after a message is given to a caller , during which delay the caller may invoke alternative processing or interrupt current processing . if appropriate alternative or interrupt commands are not received during the delay period , then processing continues as provided in accordance with the previously played message . the duration of this silent prompt delay is carefully selected to provide sufficient response time for the caller to request alternative processing , while avoiding a perceptible or objectionable delay to the average caller not requiring alternative processing .