Apparatus is provided for operating a dictation unit as a telephone-answering device. The dictation unit has a movable record medium upon which an announce message is recorded at a predetermined portion. Switching circuitry is selectively operable to condition the dictation unit to operate as a telephone-answering...http://www.google.es/patents/US4309571?utm_source=gb-gplus-sharePatente US4309571 - Telephone-adapter apparatus for a dictation unit
