As I wrote back in 2001, I still respond to telemarketers with, "Please put me on your do-not-call list," and I hang up.
But I think I'm going to occasionally try something new. When they pause, I'll say:
I don't do business with lawbreakers.
You're breaking the law by calling me.
Please put me on your do-not-call list.
And then I'll hang up.
Perhaps they will try to say, as they sometimes do, "But we spoke last year, and you asked me to call you back later."
That will give me the perfect opportunity to say, "I also don't do business with liars," and I'll hang up.