Robo call. Don't answer or block because it lets scammer know it a working number. Put it in your contacts as " spam".
If they call again "spam" will show as callers I.D.
Here's what I heard the moment I picked up the phone: "Stop what you're doing right now because I'm going to give you a chance to listen to an incredible message that will put at least $10,000 into your business in the next ten days! Just press 1 to listen to this amazing message! Press 2 and I promise you will never here from me again." So I hung up.