If you call the number back, the first thing they ask (by recorded message) is if you want to be removed from the call list.  I called from my work phone and just pressed 1 but they called on my cell phone.  I am trying to see if it is true what I heard that once you press 1 then they know it is a valid number then they will sell it to others.  If I start getting spam calls at work, I will know that's true and I will update this post.  FYI - they never say anything else when you call this number.  They just keep asking if you want to be removed from the list.  So even if you don't press 1, you never get to a person or know what this scam is all about.  I guess you have to answer it to figure that out.