ISP Failover with Bandwidth.com

I was wondering if someone can help figure out a solution for isp failover with Bandwidth?

Let me explain our setup:
We have two isps coming to our office (Verizon Fios and Comcast) with a block of 5 static ips for each. Verizon is our primary isp and comcast is our secondary isp. Freepbx has 2 nics installed in the machine. One nic goes directly to our primary isp. The second nic goes to a switch with all our phones connected to it.

The questions I have is:
1)Do I need to install a third nic in the freepbx box for the secondary isp?
2)Since you have to give Bandwidth an ip for your PBX, how do I have it automatically failover from Bandwidth? We use “DNS made easy” for our mail server failover and it works great. Can I use something similiar for voip?
3)If I have to install a third nic, do I need to make any routing changes for Freepbx to work correctly?

Thanks
-Dimitry

What’s the reason for not having proper dual homing, i.e. your own autonomous system number?

Before trying for poor man’s work rounds, one ought to explore the proper solution.