Yes, you can manually add a list of telephone numbers to the Blacklist memory of your Blocker. 

There are 3 ways of adding numbers to the BLACKLIST.
1) Wait for the unwanted call to ring, and press the "BLACKLIST" button (Recommended)
2) Follow step 5.0 in the 
manual at
3) To add these numbers to the blacklist, follow these steps:

a) Connect a telephone to the PHONE port for your Blocker.

b) Dial a number you want to block using the dial-pad of the telephone connected to the PHONE port (you can hang up).

c) Now, press OUT button to view the outbound calls.  Then use the scrolling Left/Right buttons to find the number you just dialed.  Press the “Blacklist” button to add it to the backlist memory. Repeat these steps for each number you want to block.