I figure that wouldn't do anything, so when I have the energy to even pick up the phone for these assholes, I usually just fuck with them. My favorite is the scam about renewing your car's warranty, because I don't own a car and never have. So I get them on the line and say, "Oh, no, my warranty is about to expire? Which car are you calling about?" And they pause, confused. "Well, I have two cars, which one is about to expire?" They always respond with, "The most recent purchase, sir." And then I go, "Well, I bought them at around the same time many years ago, I don't remember exactly which one was more recent. If you're calling about the warranty, surely you know the make and model, right?" That's about when they hang up.
One time I got a scam call trying to make me freak out by saying someone bought a $1,000 iPhone on my Amazon account and I needed to work with them to take care of the fraud. I just said, "Oh, no, I bought that! There's no fraud, nothing to worry about!" There was a very long (and amusing) pause, and then the click of disconnection.