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Analog telephone circuit for digital telephone system

  • US 4,759,059 A
  • Filed: 06/01/1984
  • Issued: 07/19/1988
  • Est. Priority Date: 06/01/1984
  • Status: Expired due to Fees
First Claim
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1. An interface circuit for interfacing between a digital connector of a digital telephone system for servicing a digital telephone device, and an analog peripheral telephone device, the digital connector interconnected to the digital telephone system through a digital communication path for transmitting/receiving control information, and an analog communication path, the analog communication path having an associated internal impedance matching that of the digital telephone device, and the analog peripheral telephone device having a different associated internal impedance, than the digital telephone device, comprising:

  • power supply means for supplying power to the analog telephone device, independent of the digital telephone system and the digital telephone device and supplying power for forming a loop termination therefor;

    summing means for adding the analog output of the analog telephone device with said interconnected analog communication path through said digital connector, to provide a full duplex audio path between the analog output of the analog telephone device and the digital telephone system, and the digital telephone device;

    impedance matching means for providing a sound-transmitting match between the associated internal impedance of the analog output of the analog telephone device, and the associated internal impedance of the analog communication path of the digital telephone system and the digital telephone device, the analog telephone device having an off-hook mode to allow analog communications between the analog output of the analog telephone device and said summing means, and an on-hook mode to prohibit analog communications between the analog output of the analog telephone device and said summing means; and

    the digital telephone device providing a digital interface between the digital communication path interconnected with said digital connector of the digital telephone system during the off-hook mode of the analog telephone device, such that control information can be passed between the digital telephone device and the digital telephone system through said digital connector and said interconnecting digital communication path.

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