Or or or when they ask you to buy something or renew a subscription or whatever you say "I'm sorry could you call back later I'm performing open heart surgery on my daughter."
Sorry I didn't read this whole thread but... the best way to get rid of a telemarketer is to try to sell them something.
Example:
telemarketer: "Hello sir/ma'am would you like to buy-"
you: "Oh hi I'm glad I caught you when I did, I'm selling 'insert product' and I was wondering if you'd like...