Numerous calls in a day, numerous days in a week, and they leave no message. I don't bother answering the call when I don't know the area code or number.
Always call, never respond when you answer. I guess as scamers they know no one is going to buy in to their crap. so they just hang up. any real company would allow you to contact them back. So clearly a scam. Blocked this number on my phone.