Did not recognize number

March 29, 2012...received a call from this number on my Magic Jack Phone...not my reg. inline phone or cell...I did answer it because I'm using that phone for a business line...I said hello a number of times, but heard nothing on the other end.  Many times, these people will clearly leave a number on the ID, but not speak when you answer, hoping that you will call them back.  If you DO this, and you're on the NO CALL list, you won't be able to report them because YOU were the one who called THEM.   I'll know not to answer this number next time.