No need to build a "terminator," just get a little digital recorder, find an unworking phone number and record the "the number you have reach etc., message, and if you have caller ID, when you see a number you don't want, pick up the phone and play that message, it's the tones that does the trick.  Then hang up.  I just picked up the recorder today, and am going to try it.
I didn't answer this number, I don't answer unknown numbers, if I miss something - SO BE IT!!!