Unknown numbers scare the hell out of me.
Like everyone else, missed call. One ring, no voicemail.

one ring. hung up.

One ring and hung up. No voicemail

Called at 12:22pm on 4-27-16, and today, 12-26-16, at 9:46am. Both times diverted by a service I subscribe to that intercepts robo-dialed calls (rhymes with SoNoHobo). I called back this time (*67) and got a recorded message, "This is Reward Redemption. You have won a $100 gift card," then offering me the opportunity to talk to them for my "free" gift or to press some number to be placed on their DNC list. Of course, I merely hung up. Since this was a second call, I blocked the number.

One ring and hung up..no message