Hi Doug,
The 7825H2 is only supported for the "Bridge" upgrade approach
to CUCM 8.5. have a look at the requirements
Supported only for "bridged upgrade" to migrate to newer hardware. In a bridged upgrade, you upgrade to the specified Cisco Unified Communications Manager version, make a backup of your software configuration via the Disaster Recovery System utility, reinstall the Cisco Unified Communications Manager version on new hardware, and restore your software configuration from backup. This server is not supported for any other use with Cisco Unified Communications Manager other than this "bridged upgrade" procedure.
Supported Cisco Unified Communications Manager Releases by Server
Bridge Upgrade
The bridge upgrade provides a migration path for customers who want to migrate from discontinued Cisco Unified Communications Manager server to a server that supports the newest release of Cisco Unified Communications Manager.
Servers that are no longer supported, but are permitted to function as bridge upgrade servers, can upgrade and boot but will not allow Cisco Unified Communications Manager to function.
When you attempt to upgrade your Cisco Unified Communications Manager version on a discontinued server model, Cisco Unified Communications Manager inserts a message into the upgrade log. The upgrade log is displayed on the web browser when the upgrade is initiated through the Cisco Unified Communications Operating System Administration window, or you can view it through CLI if you used CLI to perform the upgrade. This message notes that you can only use the new version to obtain a DRS backup. The warning message in the log is followed by a delay that allows you to cancel the upgrade if you do not want to do a bridge upgrade.
When the system boots the new Cisco Unified Communications Manager version, a warning appears on the console that tells you that the only thing you can do with the new Cisco Unified Communications Manager version is to perform a DRS backup ("This hardware has limited functionality. Backup and Restore is the only supported functionality."). Because of the restricted visibility of the console, the warning displays during both CLI and GUI sessions.
Use the following procedure to perform a bridge upgrade:
Procedure
Step 1 
Perform an upgrade to the new Cisco Unified Communications Manager version on your discontinued first node (publisher) server. Refer to the preceding sections in this chapter that describe the kind of upgrade you want to do. Observe the warning on the console that tells you that the only thing you can do with the new Cisco Unified Communications Manager version is to perform a DRS backup ("This hardware has limited functionality. Backup and Restore is the only supported functionality.").
Step 2 Perform an upgrade to the new Cisco Unified Communications Manager version on your subsequent node (subscriber) servers. Refer to the preceding sections in this chapter that describe the kind of upgrade you want to do.
Step 3 Verify database synchronization between all nodes. You can use the CLI commands utils dbreplication runtimestate and utils dbreplication status. For more information, refer to the Command Line Interface Reference Guide for Cisco Unifed Communications Solutions.
Step 4 Using the new Cisco Unified Communications Manager version on your discontinued first node server, perform a DRS backup. The DRS backups are encrypted using the cluster security password provided at install time. You must remember this security password as the "old" password, because you may be prompted to enter this "old" password at the time of restore. Refer to the Disaster Recovery System Administration Guide.
Step 5 Disconnect your discontinued server from the network.
Step 6 Install the new Cisco Unified Communications Manager version on your new supported first node server. You must obtain and install a new license on this server. Refer to the guide Installing Cisco Unified Communications Manager. You will be prompted to enter a "new" security password, a password that is different from the "old" password you noted in Step 4. The guide Installing Cisco Unified Communications Manager describes the requirements of a "new" security password that Cisco Unified Communications Manager will accept. You must remember this "new" security password.
Step 7 Using the new Cisco Unified Communications Manager version on your new supported first node server, perform the Disaster Recovery System Administration Guide procedure "Restoring the First Node only (Rebuilding the Publisher Alone)". First, select only select the first node for restore. You can only select the subsequent nodes for restore after the completion of first node restore. Use the discontinued server's backup file that you created in Step 4. You will be prompted for the "old" security password that you noted in Step 4. For further details, refer to the Disaster Recovery System Administration Guide.
Step 8 On your new supported first node server, reactivate all services that used to be active on your discontinued first node server before the bridge upgrade. Refer to the Administration Guide for Cisco Unity Connection Serviceability.
Step 9 Verify database synchronization between all nodes. You can use the CLI commands utils dbreplication runtimestate and utils dbreplication status. For more information, refer to the Command Line Interface Reference Guide for Cisco Unifed Communications Solutions.
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/cucos/8_0_2/cucos/iptpch7.html#wp1058411
Cheers!
Rob
