You can call your local police department and tell them that you want to file a 'harrassing phone call" report. Give the officer as much detail as you can along with the phone number that shows up on your caller id.
I just received the same call. Caller left voicemail saying that they are with the CDC (Center for Disease Control conducting a survery on my cell number was randomly chosen to participate in a survey on smoking and tobacco use and that they would call back at a later time.
I called the number back that showed up on my caller id and after a few calls finally go a live person. I spoke to a lady name Carla, and told her that I wanted to be taken off of the calling list. She asked said that she would make a note not to have my number called anymore. I told her that if I received anymore phone calls from them, that I woud file a police report for harassing phone calls using her name as the person contacted.
(To file a 'harassing phone calls" report, just contact your local police department and give the officer all the information that you have on the call including the number that appears on your caller id, if you spoke with a person, provide their names as well.)