At&e Corporation

Thomas D Klarquist

Michael C Park

Bruce C Nepple

Daniel C Olin

Dennis J O'Brien

Paul G Hanson

Robin R Rosas

Lawrence B Park

Kai-Dick Lee

William G Hood

A voice mail system includes method and apparatus for muting a previously recorded audio signal upon detection of a DTMF signal to differentiate between recorded DTMF signals and valid DTMF commands. A DTMF signal detected after muting is recognized as an invalid command.

Voice mail system with improved detection and cancellation

The present invention is a magnetic tape-based 'voice mail' multi-user message system. The system transmits audio prompts to callers to help guide them through the various procedures. The callers respond with Touch-Tone commands. A novel circuit is provided to detect these tone commands without significant interference from the audio prompt signals. This circuit is highly insensitive to deviations in the impedance of the incoming telephone line from its expected value. A circuit is also provided to prevent Touch-Tone commands which are recorded on tape from being re-executed when they are played back from the tape. A single L.E.D. indicator on each recipient's telephone set indicates the status of the system: idle with new message waiting; idle without new message waiting; busy with new message waiting; or busy without new message waiting.

Voice mail system on magnetic tape

Growing community of inventors

Beaverton, OR, United States of America

Thomas D Klarquist