| 379 / | HD | TELEPHONIC COMMUNICATIONS |
| 67.1 | DF | AUDIO MESSAGE STORAGE, RETRIEVAL, OR SYNTHESIS {13} |
| 88.22 | DF | .~ Message management {3} |
| 88.23 | ![]() | .~.~ Controlled by subscriber or caller {2} |
| 88.24 | DF | .~.~.~> By generated tone |
| 88.25 | DF | .~.~.~> Message storage in centralized location (e.g., central office, PBX, etc.) {1} |