I don't think it's supported in 5.x
The only thing in the release notes is "Cisco recommends that you connect each Cisco Unified CallManager node to an Uninterruptible Power Supply (UPS) to provide backup power and protect your system against a power failure. "
Whereas the 6.0(1b) notes has a section on graceful shutdown depending on your model of MCS:
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/rel_notes/6_0_1/cucm-rel_note-601b.html#wp263712
Also there are APC documents talking about CUCM 6.X.
The CLI command "show ups status" would appear to be missing from my 5.1.3 installation!
Sorry not much help!
Matty
