Bob, I long ago quit blaming the person on the phone for the phenomenon of telemarketing. They're folks earning very little money who have others monitoring their phone calls and saying stuff like "You gave up too quickly. When they say they're not interested, ask them if they don't care about saving money. Remind them that the first 3 months are FREE, yada, yada." It's the phenomenon I despise, not the human on the end of the phone.

I HAVE however gotten to the point where I've said (as pleasantly as possible) "I think you should give up now and say goodbye" or "I'm going to hang up now - bye-bye." and then hung up.