**I did not pick up the phone and my answering machine is off so they do not know whether it is a live number or not.**
Sure they do. They didn't get a telephone company "number disconnected or not in service" message, so they know your number is good, regardless of whether you answered it or not.
This was a call to see if you wanted to get in on the lawsuit for the IVC blood filter. First would trust a law firm that robocalls people talk about a twist on the term ambulance chaser. Sure they will have their class action suit and you will get nothing. This is just a SCAM do not fall for it!!!!