AT&T Definity ISDN 7507 - Manual (Page 21)

Call Coverage
To answer a call for a 1 Press

xxxxx

of incoming call when ring begins or
co-worker for whom you green light flashes
are a coverage point
Note: The call is not at your voice terminal until
the light is flashing.
To leave a message for a 1 Press

Coverage Callback

while connected to the call
co-worker to call the [confirmation tone]
original caller’s extension
Note: To leave a message for a co-worker to call
you, activate Leave Word Calling instead.