Yes they sell it to the telemarketers to scrub their lists.  How else would they know which numbers not to call?  Perhaps they should hire Kreskin to use ESP?  This is simple, legitimate telemarketers abide by the law, just like honest citizens abide by the law.  Since the people calling you are probably criminals, they ignore all laws.  Plus I have a very good idea that you have no idea what the DNC does and does not cover because you can't comprehend the information on that site (since this is a survey, not a telemarketing call).  Or possibly you don't want people to sign up so that you can legally call them.