I'm registered on the do-not-call list which means nothing these days. When I called the number back to be removed from "their" calling list, I listened to a 22 minute sales / marketing presentation that wanted me to pay between $1000 to $20,000 to get plugged into their marketing system and earn thousands of dollars per month. At the end of the presentation they have you leave your name and number and a level of interest (Lead generator) so that someone can call you back to give you further information, a web site address, and sign you up to get your money. I left my name and number and asked them to remove me from their auto-dialer call list, and asked how they screen numbers to see if they're on the do-not call list. I don't think I'll be getting a call back...lol.

By engaging them, you ensured, that you will receive more calls from them, but other scammers, as well.  No one compelled you to call them back, and listen to them.  Why would you call back thieves, in the first place?