The DNC list does NOT work with scammers. It's a typical worthless federal program that sounds great but has no teeth to maintain compliance. Your tax dollars down the drain or more properly into some crook lawmakers pocket!
DNC is meant for the guidance of law-abiding telemarketers. But it is not perfect and will not stop determined scofflaws and criminals. People are prosecuted under the DNC law. It's basically a good program. But it isn't perfect. That doesn't mean it's worthless. There's not much anyone can do about overseas scammers.