Zoom ADSL X6v 5697 - Manual (Page 48)

Outgoing Call Blocking
This feature applies to both VoIP and standard telephone calls.
On the User Configuration menu, click Outgoing Call
Blocking to prevent certain phone numbers from being dialed
from the X6v.
At the Block Listed Outgoing Numbers option, select the
Enable check box. In the Blocked Call List, enter up to 30
complete numbers or numbers starting with particular digits. For
example, to block all 900 numbers, enter 900x.7. This will block all
numbers that start with 900 followed by 7 digits.
To remove a number from the Blocked Numbers List, delete it.
To remove all entries from the list, at the Block Listed Outgoing
Numbers option, select the Disable check box.
ADSL X6v User Guide 48