They are not supposed to be calling at all if your on the federal DNC period. However, it doesn't stop the illegal ones from doing just that. And yes, they are supposed to place you on a internal DNC when asked also. Charity's, some survey's and political calls are exempt from the DNC and debt collectors have their own set of rules under the FDCPA laws.
ROT, don't answer calls you don't recognize.. And when answered, never give out your information or say yes to anything.
Called today at around 11AM. I knew I didn't know the number so I picked up and said "hello?"...2 seconds later after nobody answered, I said "good bye", and hung up. These numbers never pick up quickly as they are on to their next number before they can answer their previous number. Have no idea who or what they are but do know they are somebody I don't want to talk to.