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Private automatic branch exchange system and apparatus

  • US 4,028,498 A
  • Filed: 10/07/1974
  • Issued: 06/07/1977
  • Est. Priority Date: 10/07/1974
  • Status: Expired due to Term
First Claim
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1. Apparatus for selectively coupling a telephone central office circuit to subscriber equipment, comprising:

  • first solid state means having a control circuit which is operatively coupled to said central office circuit and responsive to a ringing signal on said central office circuit to provide a signal on a ring detection circuit which is electrically isolated from said central office circuit;

    switch means connected to said central office circuit and selectively operative to complete a circuit interconnection between the central office circuit and a subscriber circuit;

    second solid state means having a control circuit which can receive a line pickup signal which is electrically isolated from said central office circuit and which is operative in response to said line pickup signal to control said switch means to complete said circuit; and

    third solid state means having a control circuit which is connected to be responsive to current flow through said central office circuit and through said switch means to provide an output signal on a line pickup acknowledge circuit which is electrically isolated from said central office circuit.

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