Sharp FO-DC500 - Manual (Page 186)

Blocking Reception of Unwanted Faxes
184
5
Entering: Enter a 2-digit number from “01” to “50” with the numeric
keys. This number identifies the fax number that you will enter in the
next step.
Clearing: Enter the 2-digit number that identifies the fax number you
want to clear, and go to Step 7.
6
Enter the fax number.
7
Press .
8
Return to Step 5 to enter (or clear) another fax number, or press
repeatedly to return to the date and time display.
START/
ENTER
STOP