Hi
UCSS is ordered on a per user basis rather than per server. You also need to decide what length of contract is required (1, 2, 3 or 5 years).
If you have access to the Cisco Configuration Tool use the top level part code UCSS-UCM and select the number of users and contract duration.
For example if you have 100 users on your CUCM system and wanted a three year contract then you would need to order the following:
UCSS-UCM Top level SKU, Unified CallManager Software Subscription
UCSS-UCM-3-100 UCSS for UCM for Three Years - 100 seats
Note that to order UCSS you need to have an Essential Software (ESW) contract in place. ESW is licensed on a per server in the cluster basis.
More details at the link below:
http://www.cisco.com/en/US/products/ps9158/index.html
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