That's because these and other scammers do not care about the DNC. They are trying to steal your money. Why would they care about following the law.
Add on top of that, the caller ID is not reporting their real number. There is software out there that can mask a phone number, its called spoofing. On top of that there is VOIP where you can buy a VOIP phone system and get a phone number anywhere in the country that is not where you are.
While not everyone who has VOIP is a criminal. Most are just using it because its cheaper than having phone service through their local provider. But the criminals use it because VOIP is hard to trace as it goes over the internet and can originate anywhere in the world.
Called and didn't leave a message. When I called back, a recorded message answered and even though they didn't state what the call was about, it stated to press 1 if you didn't want any marketing calls. After pressing one, the message stated to wait 72 hours for changes to take place. I have been on the do not call list since exception!