I found this via digg, though I don't remember the link. Still this is quite interesting.
Telemarketers make use of a telescript - a guideline for a telephone conversation. This script creates an imbalance in the conversation between the marketer and the consumer. It is this imbalance, most of all, that makes telemarketing successful. The EGBG Counterscript attempts to redress that balance.
Keep this handy and start following the script right after they shoot the first question. Best of luck.