The national DNC registry does work, but unfortunately the people who are some of the largest abusers (Politicians / Poll Takers / Newspapers / Charities) are not subject to the list. Therefore all the FTC did was reduce the competition for people's time to answer a phone call.
If you want to remove yourself from all lists, you'll want to register with the National DNC list, as well as make sure that you take down the date / time / name of company / name of person who have called you after having requested them to explicitly take you off their calling list. And if someone does actually call you, don't give them money, or your time for even the most heartwrenching subjects. Otherwise, you'll have simply opened yourself up to around 2 to 3 years of non stop monthly or weekly phone calls from everyone and their brother.