Missed call... did not leave a message

Called my cell, but didn't leave a message.  The call came in very early.  Around 6:15 AM if they were calling from Colorado.  Caller ID showed "United States".  I suspect this call originated from outside the country.  Just another useless scammer.

Called , left no meassage,,, 'UnKnown Caller'

Called 6:30 am -no message

Call answered at 0544 on 1/19/17.  Caller stated he was located in Colorado and working for Microsoft.  Said his I.D. # is MS3210.  His intent was to help me prevent a computer hacking attempt that occurred 2-3 weeks ago.  All I had to do was turn my computer on.  He had my computer 32 digit ID number and struggled to sidestep questions put to him.  He ended the call by saying I was wasting his time.  I want a way to stop these frauds from hurting people.  What can be done?