AASTRA 7106a for MX-ONE EN - Manual (Page 10)

10
Do not disturb, DND
When you activate DND, calls to your extension is not shown.
Outgoing calls can be made as usual.
Activate DND:
Lift the handset and press numeric keys * 2 7 #, Replace the handset.
Deactivate DND:
Lift the handset and press numeric keys # 2 7 # Replace the handset.