Where do you live? I'm referring to the United States' National Do Not Call Registry found here
I live in Canada, and we have the same system here. The problem resides in living in a major urban center near the border. On the east coast, large centers like Boston, Chicago, Detroit, Montreal, Toronto and to a certain extent, New York are so close to each other, and the long distance calling rates are so low, that when these "Do not call" registries came into effect, the larger telemarketing outfits resorted to setting up operations across the US/Canada Border. If a telemarketer is based in Canada, the FCC can't do anything, and the opposite holds true, if an American Outfit calls people in Canada the CRTC can't do squat.
The local talk radio morning man has run 2 hour segment about this tactic when it became a prevalent practice, because it is his pet peeve. According to the specialists he had on the show, it's pretty much the same gimmick in all big urban centers along both the Canadian and Mexican borders, from the Atlantic to the Pacific. The morning team have even has a running joke about winning a cruise when the weather's bad...
Since mid 2012, myself, I've "won a cruise" every two~three months, according a to robot-calling machine.... What can you do....