Abstract: 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.

Abstract: A wide area paging system is disclosed in which paging messages input to the system in one local area can be broadcast to a receiver in any other local area without necessarily broadcasting the message in all areas. A local area clearinghouse in each area stores resident subscriber data including current location and receiver serial number. This data is used to transfer messages over a data network to the correct clearinghouse. The system uses a TDM data protocol. The data is encoded and transmitted at a very high rate (e.g., 19,000 baud) in short packets (256 bits/13 milliseconds) via stereo FM sidebands. Receivers are assigned to receive sequentially numbered time slots matching a portion of their address. The addresses of intended receivers are included in the data packets. Battery-powered receivers are deactivated between packets and reactivated in accordance with the sequential time slot number scheme to receive an incoming packet.