Snom 220 - Manual (Page 41)

Call Register
41
The numbers to be denied are displayed here.
Key mapping:
Scrolls to the next number.
Scrolls to the previous number.
Deletes the current number.
Pressing this on <New Item> will add a
new entry.
CANCEL
Returns to the idle state.
Or use the web interface “Address Book” page:
The numbers to be denied are displayed and marked with contact type
“deny”.
Adding a number
While you are being called you can press the deny list key . This
will not only deny the present all, but will also add the number to the
deny list.