Failover

The failover functionality also requires Microsoft DNS Load Balancing functionality. When integrating MX-ONE and Exchange UM, the same configuration is valid for both failover and load balancing.

In a scenario where 2 Exchange UM servers are used and one of the servers is unavailable, the first call will be attempted to set up to the first server, but it will be redirected after a few seconds and answered. Then subsequent calls will be redirected and answered in the second Exchange UM.

The reason why it takes some seconds before getting answer is that the INVITE is sent to the first server, then the system waits 4 seconds for an answer. If no answer is received, the host is grey- listed for 32 seconds and an INVITE is sent to the second server.

For more details, check MX-ONE SIP Route command description in the CPI or sip_route –help, parameter remoteport.