Has called me cell.  Some kind of poll research. What can I do to stop th?

These ppl are persistent. I have asked that the put me on a do not call list. However, they call about once or twice a day.  It is a survey company. It is not known if they do surveys for other companies but when they called my number is was for Alfa Insurance. They were not buying or selling. Just conducting a survey. I did not do the survey. I just hung up.

who called me

Somebody called my cell phone from this number

Called home phone with Caller ID listing stated Name Blocked.  Did not leave a message on machine.