We are running CUCM 6.1(2)2000-1. We have two Cisco CUBEs running 12.4(20)T4 adenterprisek9_IVS-mz feature set. Call processing works fine with both CUBEs. However, when we do a failover test RTMT shows that the CUCM continues to try to use the first SIP trunk in the route list no matter which CUBE is listed first. I have tried placing both SIP trunks in the same route group with a top-down algorithm and I have tried placing the SIP trunks in separate route groups in the route list with the same results. In the enterprise parameters the "Retry Count for SIP Invite" was set to 6 but we waited two to three minutes for failover to occur and it never did. I have changed this parameter to 2 since the initial test which should decrease the time to failover. We have another setup similar to this with another customer but they are using CUCM 7.x and are experiencing no problems. I have been unable to find a bug for this in the bug toolkit so far. What could be causing this issue?