In the past, I managed to keep a scammer on the phone for an hour or more simply by leaving it on speaker phone and making various "oh really, interesting tell me more" sounds while half paying attention. On more than a few occasions I eventually caused the scammer to either crack up laughing-- after I got tired of stringing them along and hit them with a devastating pun-- or freak out screaming at me.
But in the last two years I've _never_ been able to bait one out long enough for them to have scammed me if I had been an eligible mark and not for the lack of trying. The majority of the scam calls just end up hanging up before I ever get to a human, the majority of those that do make it to a human hang up as soon as they hear my voice. The majority of those that don't immediately hand up, do after a couple back and forth interactions.
"You've been selected to get $1000 back from the IRS for being a great taxpayer!" "Oh man, thats great!" <click>
"You've been selected to get $1000 back from the IRS for being a great taxpayer!" "Really? How did that happen?" <click>
"You've been selected to get $1000 back from the IRS for being a great taxpayer!" "Whos this again?" <click>
I'm wondering if they're now doing some kind of demographic profiling using my voice-- e.g. I don't sound enough like an aged or mentally impaired pensioner, or perhaps even have some kind of machine-learning time waster voice identification. ... or maybe there is some kind of meta-scam where someone is charging another scammer to handle these calls but aren't actually doing the work.
Regardless, I'd like to encourage all of you to do your civic duty and waste a scammers time. It can be done with very little effort on your part and it almost certainly protects real potential victims (even with my frequent hangups, my actions are almost certainly extending protection via false positives, if nothing else). I have confirmed that these actions have not increased or decreased the rate of scam calls I get relative to my SO who doesn't engage in this practice (because she simply does not answer unrecognized numbers at all).