no message left

Got a call from this number yesterday (9/28/2016) at around 7 PM.  Caller ID showed up as "Out of area 1-720-862-3915".  Let it roll thru to voice mail.  They didn't leave any message.  Tried calling the number back today.  It goes to an automated phone system with a generic message about what their office hours are -- but doesn't give any indication of a company name.  If they try calling back again and don't leave a message, I'll add the number to my Call Block List at that time.

I received a call from this number yesterday and today. The caller didn't leave a message. I called the number back today and a man answered, I hung up on him and blocked the number.

Called 9/28/16 @ 4:28 PM. Left no message.

Called our "unlisted" number, did not leave a message.  Annoying!!!!!!!!!!!!