It basically marks a station as busy when turned on. If busy or busy/no answer forwarding is active on the station, then calls to it (internal or external) will immediately forward to the forwarding destination without ringing the phone. When DND is turned on, essentially no calls can reach the extension, including paging.

The DND button on the attendant's station is not actually do not disturb. The function of this button changes to controlling the day/night mode instead.


Ed Vaughn, MBSWWYPBX