Here's how I answer telemarketer calls: "Federal Bureau of Investigation - Dallas Office. How can I help you?"
Boy, does that flip some people out when they think they're calling the FBI!
I tracked call phone numbers for a month, just for giggles. (hey, I'm retired and bored and sick of the bratty grandkids...give me a break) Every incoming telemarketer call that I used the FBI spiel on NEVER called back.
Probably unethical, pretending to be a government agency, but what the hell?! Makes me feel good that I got a
bunch of these people to stop calling.