| 379 / | HD | TELEPHONIC COMMUNICATIONS |
| 90.01 | DF | TELEPHONE LINE OR SYSTEM COMBINED WITH DIVERSE ELECTRICAL SYSTEM OR SIGNALLING (E.G., COMPOSITE) {8} |
| 93.01 | DF | .~ Having transmission of a digital message signal over a telephone line {9} |
| 93.05 | DF | .~.~ Terminal interface circuitry {2} |
| 93.07 | ![]() | .~.~.~ To plural lines or networks |