Who are these people? They keep calling my cell phone and not saying anything

This ph number call  my cell all the time and the person on the other line will not say a thing.

On June 28, 2012 at 2:37pm PST, 650-419-5566 phoned our home number, our caller ID only had "California" and the number.  We were waiting for a call from a California State agency, thinking it was them, we answered.  It turned out to be a telemarketer, who tried to sell us something?  Unable to understand what right off, they said we had called them asking about their product, which was a total lie, as we had not!  We are on the DNC list.  The only nice thing... it was not early morning or right at dinner time like they mostly do!

Got called from the # 650-419-5566 says that I ordered something but the order didnt go through so he will help me out to complete the order but I said I didnt order anything  and he hang up...............

Call and don't leave a message. I call the number back and get a message that it isn't a working number.