Sharp UX-51 Operation Manual page 73

<P=002>
Blocking Reception of Unwanted Faxes
4
Enter the full number you want to block
(max. of 20 digits).
5
Press the START/MEMORY key.
6
Return to Step 3 to enter (or clear)
another number, or press STOP to exit.
72
5 5 1 2
5 3
(Example)
START/MEMORY
STOP
Step 3 or
4