The Do Not Call list works for legitimate businesses. The ones you are getting calls from are breaking the law so anyone who trust them enought to give them private information is probably going to pay the price for their stupidity.
The only thing that talking to them will do is waste some of their time. They are NOT going to give any information to you about who they are until they are sure you are really sucked into their scam, and then probably not then either. They are probably just going to steal your money and run.
The number is not valid either. It is a spoofed number. They change numbers frequently so you can't really block them.
If you talk to them they will just sell you number to someone else.
The supposed trick of hitting # several times has a downside too. That is supposed to make the autodialer think it is not a personal number, but a FAX machine. Bad idea. You don't want someone sending FAXes to you home phone or cell number. That's worse than having an autodialer call.
Your best bet is to not pick it up and complain to the FCC. Not a good option, but probably the only real option.
I wish there were some way to give these folks bogus info that would flag them by the credit card company when they tried to use it.