3Com NBX 900-0208 Telephone Manual page 69

The associated status light does flash when a call arrives.
You can use the telephone to dial outgoing calls.
You can use the telephone to dial internal and external pages.
a 3Com Business Telephone or 3Com Manager's Telephone does not
broadcast incoming paging messages over the speaker.
If your telephone is part of a call pickup group, no other telephone in
the pickup group can retrieve a call that comes directly in to your
telephone. The incoming call goes immediately to the call coverage
point (voice mail, auto attendant, or other extension).
If your telephone is part of an ACD group, a hunt group, or a calling
group, incoming calls to the group ring on your telephone. Calls
coming in directly to your telephone (not directed to the group) do
not ring on your telephone. To prevent every call from ringing, you
must enable Do Not Disturb and also log out of the group.
To set Do Not Disturb on a 3Com Manager's Telephone:
1 Press the Features soft button.
2 Scroll to Do Not Disturb.
3 Press Select.
To cancel Do Not Disturb:
1 Press the Features soft button.
2 Scroll to Do Not Disturb.
3 Press Select.
You can also use the Feature Code 446 to turn Do Not Disturb on and
off.
To view your current Do Not Disturb setting even if you do not have a
3Com Telephone or if you are away from your desk, log in to NBX
NetSet > User Information > Feature Settings.
Do Not Disturb 69