Hello, I am looking to get a Mitel 5000 HX or a NEC SV8100 phone system....plan is to have a T1 line with PRI for service. However if that T1 line goes down then we are with out phones...What would be a good solution to have in place as a backup? I was thinking perhaps having another T1 line? so in case the main one goes down it would failover to the backup...is that the best solution for redundancy?