Cisco CallManager does not function properly if the Microsoft Windows hostname is changed after the installation of the Cisco CallManager on the Media Convergence Server (MCS) because the Structured Query Language (SQL) database does not support the hostname change.
If a hostname change is inevitable, then the entire Cisco CallManager should be re-built.
However, changing the IP address of the server is supported. To change the IP address of the Cisco CallManager server, follow the directions in
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a0080094601.shtml