Also, if you want to waste some time, but really have fun, you can turn the tables on the telemarketer:
Telemarketer Counter Script
Telemarketers use scripts. Why not use your own? Does your telemarketer have good dental coverage? Even if you won't use the Telemarketer Counter Script, check it out. It's a hoot.
Oh my word, Burmashave, I just used this counterscript on a telemarketer, it was hilarious! He opened right up and started talking. I don't think he knew what hit him!!!
He was apprehensive at the first question "how do I spell your name" but I just moved on in the easy to follow script. It was a hoot! I had total control over the conversation!

He makes $9.75/hour occasionally bothering someone like me! Doesn't like his job, uses Colgate Total toothpaste, what a riot!

Thanks for that link.