:-) My wife plays along with them. Drives me nuts. Usually something like this:
Telemarketer: "Is [xxx] there?"
Wife: "May I ask what this is in reference to?"
T: "Oh, well we have blah, blah, blah and ..."
W: "Is he expecting your call?"
T: "Well, he did sign this card asking for information."
W: "I'm sorry to say I haven't seen him."
T: "Do you know when he'll be back?"
W: "Unfortunately, no. He died last week."
Or just anything without really saying whether the guy lives there or not.
I like to switch up foreign languages:
"Is [XXX] there?"
"L'Hopital de Notre Dame, Department d'urgences."
"Excuse me?"
"What?"
"Is [XXX] there?"
"Nyet, nyet...ya nye panimayu. Gavariti pa russki?"
"Pardon me?"
"What the hell do you want?"
"Is [XXX] there?"
"Quoi! Qu'est'ce qu'il n'y'a encore?"
Heck, at that point, accuracy doesn't even matter, as long as it's foreign-sounding.
Great fun!
I have a very young sounding voice. I have had relatives and friends ask for my mom when I answer the phone. So, I use it for telemarketers. One yo-yo from the New York Times called asking for my parents. I said my mom lived somewhere else and my father was dead. He still had the nerve to try and sell his paper.