US PATENT SUBCLASS 379 / 236
.~.~ D.C. signalling over trunk

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

219  DF  PLURAL EXCHANGE NETWORK OR INTERCONNECTION {6}
229  DF  .~ Interexchange signalling {6}
236.~.~ D.C. signalling over trunk {1}
237  DF  .~.~.~> Pulse or digital signalling {2}

DEFINITION

Classification: 379/236

D.C. signalling over trunk:

(under subclass 229) Subject matter wherein the control or supervisory signal is represented by the presence or polarity of the current or voltage in a particular circuit.