If you feel the DNC list doesn't work (which it does), why do you keep adding your number to it? Which you don't have to do, by the way. Once you add your number to the list, it's there until you remove it.
Got called twice from this number, first time they didn't leave a message, second time I answered and it went to a ringing phone that nobody on the other end picked up. I called back twice and it went to a fast busy signal both times.