379 / | HD | TELEPHONIC COMMUNICATIONS |
FOR 112 | DF | TELEPHONE LINE OR SYSTEM COMBINED WITH DIVERSE ELECTRICAL SYSTEM OR SIGNALLING (E.G., COMPOSITE) (379/90) {8} |
FOR 115 | DF | .~ With transmission of a digital message signal over a telephone line (379/93) {4} |
FOR 119 | .~.~ By voice frequency signal (e.g., tone code) (379/97) {2} | |
FOR 120 | DF | .~.~.~> By modulated audio tone (379/98) |
FOR 121 | DF | .~.~.~> Having acoustic link (379/99) |