If you are an AT&T post paid customer, be advised AT&T has just launched a free product to address these very issues. It is an app named CALL PROTECT. So if you have an AT&T post paid account you can download it for your smart phone. It will hopefully be available soon for pre-paid accounts (a/k/a GoPhone).
I have been opted into a list due to an inquiry about short-term health insurance. I've received 10+ calls from a combination of this number and several other in the past hour despite asking to be removed from this list.