Start Tone Test (Line Monitoring) feature
From Zenitel Wiki
| Feature: | Start Tone Test |
| Default directory number: | 7885 |
| Feature number: | 90 |
| Parameter 1: | 0 (N/A) |
| Description: | Service: Run a Tone Test on all stations (2-5 minutes).
Line errors reported to the system log. This feature can be used independent of periodic tone test. |