OF course the No Call List doesn't stop them. It's not a call blocker and they're scammers who ignore the law. Invest in a real call blocker or at the very least, don't answer calls from numbers you don't recognize and don't call numbers back "just to find out who called." If they don't leave a message, they aren't worth your time.
They called, I answered, silence on the line and they hung up after about 5 seconds. I called them back and the automated answerer gave me to option to remove myself from their list if I am no longer interested in receiving their offers or promotions. I selected to be removed, then blocked their number.