Failover solution involving two T1s

Hi all,

We’re looking to replace our firewall/VPN box.
It’s a netscreen 25. The goal is to get a box that does firewall/VPN and can handle failover.
The layout right now is that we have two T1 lines.
One is voice and data and the other just data.
We want to connect both T1s to a firewall/VPN box.
In the event of the T1 (just data) line drops, the box knows how to auto failover to use the other T1 VPN tunnel(with policies setup). Preferably a cisco solution.

Thank you. Any help appreciated.