Looking for feedback on T1 failover hardware

We are looking to use a hardware A/B failover switch to connect our 3 T1 lines to our new Asterisk PBX servers (1 primary and 1 backup).

We will be deploying our Asterisk servers with Digium Wildcard TE411Ps.

Conceptually, we want to use Heartbeat (www.linux-ha.org) as a mechanism for indicating a hardware failure and to automatically switch routing of our T1s from the primary * server to the backup * server.

Has anyone used the PLS-345 failover switch from www.wti.com?
Does it work in conjunction with Heartbeat?

Anyone else successfully using something different?

Any comments from users with deployed T1 failover systems would be greatly appreciated.

Thanks,
AntD

have you tried with ISDNguard or foneBRIDGE2?
Both work with Heartbeat in diferent ways (pure PRI and TDMoE).

junghanns.net/en/ISDNguard_produkt.html
red-fone.com/Products/