US PATENT SUBCLASS 379 / 237
.~.~.~ Pulse or digital signalling

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  DF  .~.~ D.C. signalling over trunk {1}
237.~.~.~ Pulse or digital signalling {2}
238  DF  .~.~.~.~> Having signalling repeater
239  DF  .~.~.~.~> Using register-sender

DEFINITION

Classification: 379/237

Pulse or digital signalling:

(under subclass 236) Subject matter wherein the control or supervisory signals are represented by the time pattern of abrupt variations in a specified signal.