Upgrading CUCM from 11 to 12.5

[nicanor00]

Hi

I need to upgrade CUCM/CUC 11.0.1.21900-11 to version 12.5.1.10000-22

I have server ucsc-c220-m4s and Esxi 5.5

I first plan to upgrade ESXI 5.5 to 6.7 : I will like to know if my server can support ESXI 6.7

Kindly help with documentation or yutube tutorial that you use for the ESXI upgrade and CUCM/CUC upgrade 11.x to 12.5

Thanks so much

[Jaime Valencia]

That information is on VMware's compatibility site, you can find it very easily, as well as the ESXi upgrade instructions, you can find all you need with just a few minutes in google.

As for CUCM/CUC upgrade:

Mandatory reading regardless of what upgrade path you choose, all for target version 
 
A) Upgrade and migration guide
B) Release Notes 
C) Compatibility matrix (depending on product might be a standalone doc, or within any of the other docs I mention) 
D) README from ova
E) HW/ESXi compatibility 
 
After reading all of the above, you'll have all the information to plan the upgrade. 

[Roger Kallberg]

Apart from the amazing information already received from Java I would recommend you to upgrade to a newer version of CM 12.5 than the one you have listed as that is the base release of the 12.5 release train. There are 6 SU releases out there for 12.5, my advice would be to go for 12.5 SU6.