They call every other day. I finally heard the recorded message. Like others have mentioned, they are offering security services. At the end of the message, they tell you to press 1 to speak with a rep, 2 to be removed.

I have hit 2 twice. I have also blocked the phone number locally on my phone in addition to in my Verizon account.

The number still gets through...which is a clear indication that the 602 number is just spoofed...that is not the true phone number that is calling you.
 Jan 08th, 2014
Received call from this Arizona number, I live in NJ. They didn't say a word...just sat there for 60 seconds quietly
 Jan 02nd, 2014
some sort of security system company
 Dec 26th, 2013
No reason to hear from area
 Dec 26th, 2013
was talking about the fbi reporting break ins and then asking to allow them to put a sign in my yard and installing surveillance tech
some guy
 Dec 11th, 2013