It's a Memphis area code but the calls aren't originating from Memphis. VOip (Internet phone service) has changed the game in telemarketing. Now telemarketers can register for numbers all over the country and use them to target homes in the same area code. You're more likely to answer the phone if the call appears to be originating from a local number.
They don't pay attention to that list. To receive that list is just a way for them to get your number. And they could care less about getting caught. Which they probably never will. Who's the DNC police anyway?