Sadly, as has been pointed out before, these calls are from foreign countries - they fake the caller ID so you think they are domestic but they, for the great majority, are not. Therefore our USA Do Not Contact list is useless. Our government has no real clout for the most part, those countries don't/won't follow our laws - I mean, IF they are going to scam you why would they care about breaking the DNC list?
The DNC list will protect you against legitimate, honest USA based companies who are willing to adhere to it. Charities, surveys and political calls are exempt too so it really doesn't do much at all.
A new interesting twist on Robo Calling Spammers: (AreaCode) 555-0xxx. Every number has the 555 and 0xxx in common and all are fake if try to return the call,
Here is the list started this week on my block list:
760-555-0160
907-555-0173
414-555-0128
623-555-0147
802-555-0163
They called some Indian guy who can barely speak English talks about something with your computer and I responded back I don't own one and he was confused as hell.