When I started getting these calls, they wanted to speak with my wife (who had already told them she wasn't interested in the previous 20 calls). I let them pitch their sale then simply said "Wait, let me go get my wallet." Then, they were introduced to a full-blast of television static - enough to injure anyone wearing a headset providing they didn't have the necessary protective means. They called back two more times IN FIFTEEN MINUTES with the same results. For the last few calls, they got a guy to call me as if he'd "connect" better with me because we're men. He got the same treatment. This went on for at least 2 hours at a call roughly every 10-15 minutes. Seriously, I was doing everything I could think of to entertain myself at their expense from speaking babble to a referee's whistle to giving the phone to my 2 year old until they hung up. They called back a final time and I let my wife answer before giving me the phone (they had started hanging up outright whenever I answered) - this time, they were met with high-volume speaker reverb (what happens when you put a microphone up to a speaker). They haven't called back in four days. I guess a room full of deaf idiots painted a clear enough picture that I wasn't interested in their scam.
I know it sounds incredibly childish for a 30-year-old man, but that's what it takes when the threat of legal action does nothing but make them laugh and call back.