you must adhere to the compatibility matrix. While integrating UCCX with an unsupported CUCM might work, there would be no guarrantees that such integrations would be free from errors. And of course, Cisco won't talk to you when you raise a support ticket if they find out this is an unsupported configuration.
Some UCCX versions will support multiple CUCM major versions. You will have to reference the latest CCX Compatability matrix. If you're upgrading to CUCM 10.5, you may not have a choice, but upgrade to UCCX 10.5.
UCCX 8.5(1)SU4 supports up to 9.1(1)SU1.
8.5(1)SU2 and prior only supported up to CUCM 8.6(2a)SU3
I'm not able to access my old voice mail messages all of a sudden. The recording says something like 'the message is currently not available'. This has never happened before in all the years I have been using this system. I have t...