I've heard twice now that the majority of telemarketers work out of India. I got it from two friends who work for American Express since they have to deal with AMEX's telemarketing division (based in India). They say that all major credit card's telemarketing divisions are run out of India and most 1-800 numbers route to India.

Now I'm not saying this is true, I still don't really believe it. But they told me that the way you tell is the slight tmie differece between the conversation, and the accents. The Indian workers are told to speak in the most American accent possible and since they call hundreds of people a day they get alot of pracitce and quickly develop the accent. But you can usually still hear inflections on certain words.

Anyway next time you get a call try to see if they have an accent, or just ask them if they are in India, I haven't tried that yet.