Cisco Unified Communications Virtualization supports multiple applications co-resident on the same Cisco UCS server. For small and mid sized business with upto 1000 users, the following UC applications can be co-resident on one low cost Cisco UCS C200 server:
CUCM 1000 users
CUC 1000 users
CUP 1000 users
CUCCX 100 users
For further details or other supported UC virtualization deployments, pleae refer Unified Communications Virtualization Sizing Guidelines http://docwiki.cisco.com/wiki/Unified_Communications_Virtualization_Sizing_Guidelines#Introduction