Cisco Unity Connection 12.x with Two CUCM Clusters

[mtaneja712]

Hi,

We have two CUCM version 10.5 Clusters . Cluster A at Site HQ and Cluster B at Site Branch.

They are connected through SIP ICT. 

Now we are trying to introduce Cisco unity version 12.x at Site HQ. 

My questions are

1) Can single Unity 12.x cluster can provide voicemail services to users in both CUCM cluster A and cluster B.

2) How the CUCM clusters would integrate to to the single unity clusters ? Would that be a direct sip connection from each CUCM cluster to unity or SCCP connection or Unity would integrate on to one cluster and calls from otehr cluster would route through SIP ICT ? How users will access the services ?

3) Limitations , if any ?

Thanks,
Mohit

[Jaime Valencia]

Yes, CUC can integrate with multiple clusters at once, using whichever protocol you choose, as long as you have available ports for each integration.

[Jonathan Schulenberg]

Adding to Jaime’s response: for modern versions of CUCM I prefer integrating CUC with a single CUCM cluster and leveraging the ICT to the other cluster. This keeps CUC clean/simple. You just have to update your ICT with the same SIP Trunk Security Profile permissions that CUC calls for in the integration guide to allow MWI traffic to cross.

[mtaneja712]

Thanks Johnathan.

One of CUCM cluster is in USA and the other is in India. Considering we put CUC cluster in USA and don't go with ICT path, what's the round trip type supported with CUC and CUCM cluster using direct SIP trunk integration ??

Also what's the supported round trip time between CUC cluster nodes ?

[Jonathan Schulenberg]

I'm not aware of a documented RTT limit on the SIP Trunk between CUC and a phone system. Standard RFC3261 timers would apply but if CUCM has a SIP trunk between the two clusters I would expect CUC will be fine.

As for RTT between nodes in a cluster, this is documented in the design guide.https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/11x/design/guide/b_11xcucdg/b_11xcucdg_chapter_01011.html

• When both the subscriber and publisher are taking calls, the maximum round-trip latency must be not more than 100 ms. When only the publisher is taking calls, subscriber is idle but replicating with publisher, the maximum round-trip latency must be not more than 150 ms.