It doesn't protect you from the illegal callers, scammers and frauds, otherwise it works as it should which is keeping the calls toned down and non existent from real business's that would be adding much more calls to you and everyone else.  

Consider buying a call blocking device or phone..
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=call+blockers
************************************
Report them here:
https://www.ftccomplaintassistant.gov/#&panel1-1
https://esupport.fcc.gov/ccmsforms/form1088.action
https://complaints.donotcall.gov/complaint/complaintcheck.aspx?panel=2
http://www.consumerfinance.gov/complaint/

Caller left message on machine saying he is "Dave" from US Gold and Silver Advisors (yes we actually do have an answering machine and not voicemail).  Almost sounded live, but I think it was a robocall.  We've never done business with any silver/gold outfit.  So annoying that the Do Not Call registry doesn't really seem to work that well.

Who is calling and hanging up