redirecting incoming phone calls to /dev/null on the FRITZ!Box

Within the last couple of weeks I have had business calls from  a specific phone again and again. The first couple of calls were quite polite. But they all went the same way and ended unpleasantly. Now finally I created a call forwarding rule on my FRITZ!Box, that makes all calls from that phone number to go to my message recorder (that's almost like "/dev/null"). I guess that will help my peace of mind a lot.