Telemarketers
In Indiana, we have a "No Call" law where telemarketers are prosecuted and or restricted from doing business in the state for calling us at home with spam shit.
Only problem is that if you have already done business with the company, they have a sort of exemption and can call us.
However, if you are on the No Call list and want to help, the State's Attorney General has a website where you can enter all the non-welcome callers numbers you have received and from what I have seen they shut them down.
Biggest problem I have is that I use AT&T and every single day they text me with crap and sometimes call to inform me of upgrade possibilities. I can not get that shut down. I have even added the numbers they call to my "contact" info so that I can block them, but they just keep using different numbers.