Attended messaging machine

Abstract

An attended messaging system having an audio message recording and playback device connected in series between a telephone base unit and a telephone receiver handset or headset. The recording and playback device includes a solid-state audio memory chip for storing a message and pairs of operational amplifiers connecting the memory chip of the recoding and playback device with the telephone base unit and with the speaker and microphone of the telephone receiver handset or headset in a differential circuit of audio signal channels. The recording and playback device is manually-actuable by means of buttons or switches to operate in a recording mode, in which a message spoken into the handset or headset microphone is stored in the audio memory chip, or in a playback mode, in which the previously recorded message is communicated through the telephone base unit and telephone line to a designated remote telephone station with which audio communication has been established by the telephone base unit. When the recording and playback device is inactive, i.e., in neither the recording or playback mode, a person can communicate with a party at the remote telephone station through the telephone receiver handset or headset. Excessively loud sidetone in the handset or headset speaker is avoided by arranging the polarity and signal strengths of the sidetone signals from telephone base unit and recording and playback device to combine in phase opposition in a 2X--X manner.