things to "Watch out for"

[macphoneguy]

We Currently have a redundant 2k system with 11 remote Nodes, we are adding a 2nd 2k system in a different building for "Fault tolerance" i.e. something happens to the building that the 1st Main Controller is in the calls can still go through the 2nd controller, I cant think of any immediate concerns other then there being enough fiber to the Locations but are there others ?

 

[gphone]

Since you are using a digital system (not a 3300 w/VoIP) the resilency of having a second 2000 to operate the other 11 nodes may not work. Unless you are stating that the 11 nodes are actually 11 remote sites, each having an sx2000. In that case it is pretty much gravy.
You can even set route optimization on the links to switchover real time in the event a link goes down.
Also, the 2 main SX2000 systems will be networked via T1/E1, not necessarily fiber unless it is multiplexed. As long as the second 2000 has all the MSDN options and the programming fro all the other nodes is done to include the second 2K, you're good to go.