Not give them a big tiresome speech about how they are breaking the law, just ask them not to call anymore ("Please put this number on your courtesy do not call list"). They actually don't want to waste their time...
A lot of the calls I used to get were the ones where they spoof a phone number that has the same first few digits as yours to make it seem like a local number and then the caller is a scammer “You owe money to the IRS”, “Your computer has a virus and you have to pay to fix it”.
Engaging these callers is probably not useful.
Unfortunately, it still won’t prevent my number from being spammed. There is no human to talk to. Any indication you are alive is a confirmation your phone number is worth calling. The only thing you can do to convince them is not answer or somehow communicate a likely disconnection from a human.
The internet myth is that this marks you as someone to keep calling (because you listened), but really they will stop.
I mean, I get ~1 unwanted call a week across a couple of phone numbers (that I answer and ask to stop). Other people are saying that they get a dozen a day and giving up on their phones. My anecdotes work for me.