When telemarketers called, I used to actually try to talk sense with them. Along the lines of “I don’t want what you are pushing on me”. Generally this doesn’t work. They basically start arguing with you.
Now, I’ve got a really surefire way to deal with such calls. I start talking to them, maybe even answer a couple of the unimportant questions, then I simply slowly and peacefully hang up, as I am still talking to them. It has this very surreal detached feeling to it. Very theraputic. Everyone should try this. They don’t call back.