Sharp UX-B30 Operation Manual page 78

Caller ID (Requires Subscription to Service)
Blocking voice calls
If you have turned on Caller ID, you can use the Anti Junk Fax function
described in Blocking Reception of Unwanted Faxes in this chapter to block
voice calls as well as faxes from your specified Anti Junk Number.
In this case, when a voice call or a fax comes in from the number you have
specified as a "Junk Number", your fax will terminate the call as soon as it
receives the calling phone number from the caller ID service. The caller will
hear a 3-second high-pitch tone to signal the call's termination. In Australia
the call will not break off until the caller has hung up.
To use this function, enter the number that you wish to block as explained in
Blocking Reception of Unwanted Faxes (see page 78). Only one number can
be blocked.
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