Have had nearly two dozen calls to my cell phone from different numbers beginning with "720-320-xxxx," typically with no one on the other end or no messages left. This latest call came with a robo-message about a free cruise, cleverly asking me over and over again to say "okay" before I could hear their offer.  When I remained silent, the call was disconnected. (Remember the scam warnings where if you say "yes," "okay," "all right," etc., then you're considered to have committed to something?)