I normally answer my phone "This is M... C..., how can I help you?" and
> telemarketers utterly clam up when they hear it, as if I had been casting
> spells on them in the Unknown Tongue.
To be precise, here's how it goes:
"This is M... C..., how can I help you?"
(long pause) "Uh..." (long pause) "Is this M... C...?"
"Just what I said. How can I help you?"
"Uh... uh..."
I presume telemarketers are only trained to talk, not to comprehend speech.