I JUST heard about this and looked it up. Most telemarketers use computers to dial and when your phone rings it 'hands it off' to a sales person. The way this works is that it sends a signal BACK to the telemarketing computer that 'this is a non working number.' The computer deletes your number from its database. Otherwise, (if you don't answer) you are put back in rotation for another call. ARE ANY OF YOU USING THIS ALREADY? If so give me some feedback, I'm about to buy one!
Check out the link!