I have recieved a call from this number and others starting " did u know that the fbi' then i hang up . i recieved one on 1/23/14 and other days for the past month. It's on my cell phone, thought was private.
Received 2 calls at work (literallly within seconds of each other) from same number 720-452-6428 and no messages were left. Google Reverse Phone search 411.com returned Peerless Network landline from Denver, CO
I did not return their call.