A voice response unit (VRU) 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...http://www.google.com/patents/US7260187?utm_source=gb-gplus-sharePatent US7260187 - Voice response apparatus and method of providing automated voice responses with silent prompting
