Nothing that you do will stop them from calling you. The calls will continue since the major money is being made with what is called a CNAM revenue-sharing program through companies like http://www.telephonemanagement.net and http://www.CallerID4U.com.
If you want to stop these calls then you need to dry up their revenue source. These scum are making money by sending bogus Caller ID information to your phone company. Telephone numbers are Calling Name (CNAM) provisioned and stored in a special database accessible to other telecom utilities. This means that for any outbound call that transmits a special code corresponding to one of their phone numbers, these criminals collect a fee for transmitting the caller ID information to the Local Exchange Carrier receiving the call. When you see a phone number in your caller ID (along with some name like Card Services), your phone company has to reimburse the caller for downloading that info from the database where it’s stored.
They are making money even if you don't answer the phone. If someone does make the mistake of answering the phone and falling for their con then it is just icing on the cake for them.
What To Do When You Get an Illegal Robocall; http://www.ftc.gov/bcp/edu/microsites/robocalls
1. Hang Up. Do not press 1 or any other numbers to get off the list.
2. Consider blocking the number
3. Report it at http://www.fcc.gov/complaints
4. Report it at https://www.ftccomplaintassistant.gov
5. People should continually file complaints with their Attorney Generals office.
Register your phone numbers online at http://www.donotcall.gov or call (888) 382-1222 (must call from # you want removed).
Here is an excellent blog site that I found that explains how these companies are getting away with this activity. http://telemarketerspam.wordpress.com