left no message

Got a call from this number today (7/28/2016) at around 8:30 PM.  Caller ID showed "Out of area 1-303-536-6706".  I let all "Out of area" calls roll thru to voice mail.  They left no message.  Now I've added that number to my phone's Call Block List; so they won't even get to ring thru anymore.

It's that robo survey call.  It asks you some questions and then you are given the opportunity to send them some money so you can have your free gift.  It might be a gift card, discount vacation, free solar assessment, etc.  It's a scam.  Block it.

Received a call from this number, but didn't answer because I didn't recognized the number.
They left no message. I called 303-536-6706 and it's a survey service which offers you the opportunity to be removed from their call list.
I added them to my "Blocked call" list.

Just got call from this number, didn't answer, no message left of course, added to block list.