Looks very much like another "4 ring phone call"  Wherein the phone rings only 4 times - then the call is gone.  Naturally, like a growing number of people on this site, I refuse to answer any call(s) from numbers I don't recognize - and I encourage others to do the same.  So, naturally, I don't know who called, but I would be willing to bet the mortgage money it's just another scumbag criminal trying to steal money via some scam.  800 notes - keep up the good work !
BTW. - the Washington Post is soliciting comments from readers, on a variety of subjects that they want to write/publish articles about.  And, guess what ?  One of the subjects is "robocalls".  DO write to them, and give them your thoughts.  "The Post" is a widely published, prestigious newspaper, read by many members of Congress.  Here's our opportunity to have our opinions read by people who can actually do something about this. Go people!!!