My cousin figured out a great way to get on their "do not call" list. Normally they didn't care about being on this list and would just keep calling. So instead of blowing them off, he decided to listen to them. Let them run through their script, talk about everything and anything related to their product. 30-45mins later, depending on how much he felt like screwing with them, they would ask, "So can we count on you for subscribing/signing up/etc for this?"
He would tell them, "No but it sounds like a great product, you can add me to the no call list and let your friends know if they dont want to waste an hour talking to someone that won't sign up"