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CUC , CER 10.5 Compatibility with CUCM 12.0.1 SU2

Anil Sharma

Hi Team,


My existing CUCM version is 10.5.2 and I am planning to upgrade it to version 12.0.1 SU2. I understand its a standard upgrade and can be done from OS Admin.


Can someone please confirm if  my existing version of CUC and CER is compatible with my Target CUCM 12.0.1

or do I need to upgrade these applications in same Maintenance window as CUCM ?





I've already checked below however its not clear if these applications are compatible or not.


Many thanks for your help.



9 Replies 9

Thanks Jonathan for your response.

Wasn't aware if AXL integration between CUCM , CUC can make any difference.

Chris Deren
Hall of Fame Master Hall of Fame Master
Hall of Fame Master

You will need to upgrade CER as well since version 10.5 is not compatible with CUCM 12, CER is never backwards compatible with CUCM as you need to select specific CUCM version you are integrating with.

Thanks Chris for your response, I thought CER 12.0.1 is backward compatible with CUCM 10.5.

I was planning to upgrade CER to 12.0.1 under once maintenance window and upgrade CUCM to 12.0.1 later next week ?




Yes, CER is backwards compatible with CUCM, but not the other way around which is what the original question was about.

So, CER 12.0 would work with CUCM 10.5, but CER 12.0 would not work with CUCM 10.5.  Needless to say when you upgrade CUCM you should plan on upgrading CER. But you can potentially upgrade CER without upgrading CUCM.

Oops, this is what I get for answering threads _while_ having coffee instead of _after_ I have had coffee. Thanks Chris.

thanks Chris , yes I mixed it up a bit.

So, I will upgrade CER first to 12.0.1 and plan CUCM later.


I am getting a very strong confirmation from Cisco TAC CER 10.5 is compatible with CUCM 12.0.1
Below is what TAC is saying ?

"This is due to the nature of the integration through CTI. There is no limitation between each other because CUCM 12.0.1 was developed to be able to communicate with older versions of CER."

Thanks for following up, this contradicts what I've been told in the past, so I would suggest you keep the email as evidence in case you run into issues and get pushback from another TAC engineer.

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