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Time independent data transmission system having capability for accessing a plurality of data devices

  • US 4,654,868 A
  • Filed: 12/05/1985
  • Issued: 03/31/1987
  • Est. Priority Date: 08/23/1984
  • Status: Expired due to Fees
First Claim
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1. An apparatus coupling a plurality of data devices and a telephone instrument at a first location to a telephone transmission line so as to enable the communication of data between a selected one of the data devices at the first location and a second location without interfering with normal use of the telephone instrument, comprising:

  • first means coupled to each of said data devices for selecting one of said data devices in response to a code signal transmitted over said telephone transmission line;

    second means, coupled to said telephone transmission line, said telephone instrument and said first means and normally connecting said first means to said telephone transmission line, for disconnecting said first means from said telephone transmission line connecting said telephone instrument to said telephone transmission line in response to any of selected ones of a plurality of first electrical signals transmitted on said telephone transmission line, said first signals each being indicative of a call from a caller on said telephone transmission line, said second means preventing disconnection of said first means in response to a selected one of said first signals;

    third means, coupled to said telephone transmission line and said first means, for detecting any of said first electrical signals transmitted on said telephone transmission line without answering the call and for generating a second electrical signal when any of the first electrical signals on said telephone transmission line has terminated, indicating that the caller has hung up;

    said selected data device being adapted to communicate data via said first means and said second means in response to the generation of said second electrical signal after said selected one of said first electrical signals has terminated.

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