NEC Univerge SV8100 Features And Specifications Manual page 544

Issue 12.0
3. Dial the DND option code.
0 = Cancel DND
1 = Incoming Trunk Calls Blocked
2 = Paging, incoming Intercom, Call Forwards and Transferred Trunk Calls Blocked
3 = All Calls Blocked
4 = Call Forwards Blocked
Single Line Telephone
1. Lift the handset.
2. Dial 747.
3. Dial the DND option code.
0 = Cancel DND
1 = Incoming Trunk Calls Blocked
2 = Paging, Incoming Intercom, Call Forwards and Transferred Trunk Calls Blocked
3 = All Calls Blocked
4 = Call Forwards Blocked
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UNIVERGE SV8100
Do Not Disturb