US PATENT SUBCLASS 379 / 282
.~.~.~.~ Voice frequency receiver

Current as of: June, 1999
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379 /   HD   TELEPHONIC COMMUNICATIONS

242  DF  CENTRALIZED SWITCHING SYSTEM {15}
258  DF  .~ Switching controlled in response to called station addressing signal {9}
268  DF  .~.~ Having shared or common switching control {8}
280  DF  .~.~.~ Including registering or storing device for call address signal {7}
282.~.~.~.~ Voice frequency receiver {1}
283  DF  .~.~.~.~.~> Dual tone multifrequency (DTMF) receiver

DEFINITION

Classification: 379/282

Voice frequency receiver:

(under subclass 280) Subject matter which is selectively responsive to audio frequency signalling tones.