AT&T 7406BIS - Manual (Page 47)

Self-Test ✓
To test lights and 1
ringer of your voice
terminal
2
3
Press [ Shift ]
●
Green light goes on
Press and hold [
Drop
]
●
Ringer sounds
●
All columns of lights next to buttons above and to
right of dial pad go on
● Display is activated
Release [ Drop ] to end test
●
Ringer and lights return to pretest state
Note: If ringer or lights do not respond during test,
notify your System Manager.