Voice mail system on magnetic tape

A voice mail system for recording audio messages transmitted by a user over a telephone line to the system and for subsequently forwarding the messages to recipients designated by mailbox identifiers transmitted by the user, comprising:

• a magnetic tape divided into a plurality of message cells;
• means, coupled to said telephone line, for recognizing an incoming call and placing the system in an active state;
• decoder means coupled to said telephone line for decoding control signals including mailbox identifiers transmitted on said telephone line;
• processing means coupled to said decoder means for controlling the operation of said voice mail system;
• message recording means, controlled by said processing means and coupled to said telephone line, for recording audio messages in said message cells;
• memory means, controlled by said processing means, for storing cell locations in which messages have been recorded and mailbox identifiers associated with the stored cell locations;
• means for switching the system to an idle state after an audio message has been recorded and after the memory means has stored the cell location and mailbox identifier;
• indicator means located at a location remote from the message recording means, controlled by said processing means, for indicating the presence of a new recorded audio message in the system in association with a recipient's mailbox identifier;
• means for the recipient to switch the system to an active state;
• playback means, controlled by said processing means and coupled to said telephone line, for playing a message recorded in a cell in response to a recipient's generated control signal which includes the mailbox identifier associated with the recorded message;
• and
• means for returning the system to the idle state following the playback of a message.

In a voice mail system for connection to a telephone line, the system including a decoder coupled to the telephone line for decoding incoming dual tone multiple frequency command signals and including a prompting device coupled to the telephone line for transmitting outgoing audio voice prompt signals, means for preventing the outgoing prompt signals from interfering with the decoding of said incoming command signals, said means comprising:

• transformer means having a first and a second side, the first side being coupled to the telephone line;
• first voltage divider means having an input connected to the output of the prompting device and an output connected to the second side of the transformer for producing at the second side of the transformer a voltage corresponding to approximately one-half the voltage output from the prompting device;
• amplifier means having an inverting input, a non-inverting input, and an output, the inverting input being coupled to the second side of the transformer and the output being coupled to an input of the decoder, for providing to the decoder a net signal voltage equal to two times a voltage applied to the non-inverting input minus a voltage applied to the inverting input by the second side of the transformer;
• and
• second voltage divider means having an input connected to the output of the prompting device and an output coupled to the non-inverting input of the amplifier means, for producing at the non-inverting input of the amplifier means a voltage equal to one-fourth a voltage output from the prompting device, whereby the amplifier means provides to the decoder a net signal devoid of voice prompt signals.