CUCM 12.X to 11.5 OS downgrade Is it possible?

[baechangmin]

Hello

CUCM 12.X to 11.5 OS downgrade Is it possible?

What OS should I get from Cisco homepage?

Can you give me a downgrade guide?

[Jaime Valencia · Accepted solution]

No such thing as a downgrade, closest thing is to rollback to whatever version is in the inactive partition (losing all the changes made after switching the partition) 

[kschoi7281]

If I can't downgrade
We need to erase the existing 12.x and install a new 11.5.
Thank you for your reply

[Jaime Valencia]

Bear in mind that if this is a new purchase, the licensing is version specific and pre-12 uses PLM while 12+ uses smart licensing.

[Anthony Holloway]

Just curious, why would you downgrade?

[kschoi7281]

Our client wants to install the version.

[Anthony Holloway]

That clears it right up. Thanks.

[H-Alashi]

Hello  baechangmin,

kindly note that the downgrade concept is not supported on CUCM.

you can switch versions in between the active and inactive partitions.

and no lower version can be uploaded to the CUCM than the current on the both partitions.

Regards,