Single Unity with Multiple CCM clusters

[jsailers]

I know this horse has been beat to death, but I couldn't find a specific answer to my question.

I understand with Multiple clusters, Calls from each CCM to Unity go over the Ports configured as such in each cluster. I also understand that MWI notification is sent out the highest numbered port and works it's way down until it's successful. What I don't understand is how transfer out of Unity to a subscriber's extension works. How does Unity know which CCM Cluster to send the call to? Does it send it out the primary cluster and that cluster is responsible for routing the call over an Inter-Cluster Trunk? Or does it behave like MWI where it tries to send calls out from the highest numbered port until it is able to place the call?

[mrmccann · Accepted solution]

All calls initiated by Unity (transfer and message notification outdials alike) are just made on one port, the call is not retried on other ports like MWIs.

The difference is that for notifications, Unity will just use the last available port on the last cluster. So you need to have the ICT set up correctly so the call can get routed to the correct phone on another cluster.

For transfers, Unity will initiate the transfer using the same port the call came in on. So if the transfer is supposed to go to a phone on a different cluster, again you need your ICTs set up between clusters so that Unity can transfer a call from one cluster to another.

In both cases, Unity is just dialing, it doesn't know whether the phone is in the same cluster or a different cluster. So you need to make sure the dial string Unity is using, together with the dial patterns in CCM, get the call routed properly across the ICT.