CUCM-CUC SIP Integration

[Harish Inuganti]

I have a general question on SIP integration between CUCM and CUC. I am planning to use "Run on All Active CM Nodes" both on the Route-list and SIP Trunk pointing to the Unity Connection. With this feature I understand that the CUCM local to the calling device (i.e phone) will be used on outbound calls to Unity Connection. So, i believe I'll need to add all the servers under SIP Server set-up in Unity Connection. Is there a particular order in which i'll need to add these SIP Servers under Port-group or would all the servers get an order of "0". Does it matter at all? I am a bit stumbled upon how the communication would happen the other way around (i.e. Unity Connection to CUCM). If CUCM uses the node that the phone is registered to communicate with UCN. Would UCN also use the same CUCM node to talk-back to or would it now pick another node based on the order of SIP servers listed in port-group set-up?

[Jonathan Schulenberg · Accepted solution]

The order only applies to INVITE (ie calls such as notification destinations) and Unsolicited NOTIFY (eg MWI) from CUC to CUCM. The order has no impact for calls from CUCM to CUC.

CUC has no knowledge of the CMG assigned to a phone/trunk/gateway so this is all traffic from CUC to CUCM, excluding the in-dialog traffic of calls from CUCM to CUC of course - that will always be replied to the calling parties’ CUCM node.

[Harish Inuganti]

Thanks for the clarification Jonathan. So theoretically in case of a HA cluster which is clustered over WAN, I can create separate Port Groups listing all the CUCM servers (local CUCM's first) under each port group. 

[Jonathan Schulenberg]

I wouldn't bother with separate port groups. Just balance out the order to include CUCM nodes in both DCs.