I just don't understand the recorded messages with no contact details! I've had one, and I listened very carefully for the company name (so I could lay a complaint about their advertising methods).
If I had actually wanted to give them my business how would I contact them?
I try and answer the telemarketing (or market research) calls, because DH will be quite short and hang up. I go for "Sorry, I'm not interested" or "Sorry, we have no need of that", interrupting them as soon as I can, so as not to waste their time.
Often this involves "Excuse me, but are you looking for donations? Yes? I'm sorry, but *whatever reason is appropriate*. Have a good day!"
It irks me when people are rude to people who are trying to do their job, even if that job seems designed to annoy.
But then again, I'm friendly and polite to people giving me fines and companies who have given atrocious service. Although for the latter the 'friendly' may slip after the 3rd phone call