Telephonic communications – Call or terminal access alarm or control – At substation
Patent
1988-10-14
1990-05-15
Dwyer, James L.
Telephonic communications
Call or terminal access alarm or control
At substation
379188, 379375, H04M 166
Patent
active
049264702
ABSTRACT:
An inexpensive, reliable telephone answering device screens out undesirable calls, screens the calls that are dialed out and inhibits preprogrammed call prefixes from being dialed, adds the "hold" function and a simulated call transfer function to all telephones (activated by depressing a TOUCH TONE key on a standard telephone set), provides a way to use the telephones in the home as an intercom system, and provides other advanced PBX functions at low cost in a home or small business environment. A power off failsafe feature prevents power loss to the device from interrupting normal telephone operation. Several caller access codes and several dial inhibit codes can be programmed from a conventional unmodified subscriber Touch Tone telephone set, and a personal access code prevents system programming from being changed by unauthorized persons or accidentally. These and other advanced functions previously available only in a complex, expensive telephone PBX system are made available in a low cost, optimally designed device.
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Motorola Linear/Interface Devices, manual, pp. 3-36.
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