I ran into an issue when upgrading (patching) a CUCM 7.1.2 tonight, and I couldn't see any readme files on cisco.com explaining the problem. However, I came across a blog post mentioning something similar.
When you download patches from cisco.com, they might be big and split into two or more files.
One way to merge them is using the "copy /B" in a dos prompt.
Example: When you have downloaded the two files "UCSInstall_UCOS_X.X.X.XXXXX-XX.sgn.iso_part1of2" and "UCSInstall_UCOS_X.X.X.XXXXX-XX.sgn.iso_part2of2", simply merge them by typing: "Copy /B UCSInstall_UCOS_X.X.X.XXXXX-XX.sgn.iso_part1of2+UCSInstall_UCOS_X.X.X.XXXXX-XX.sgn.iso_part2of2 UCSInstall_UCOS_X.X.X.XXXXX-XX.sgn.iso
The process will take a few minutes, and should complete with "one files copied" (You need to be in the folder where these files are located).
Once this is done, you put the merged file in a folder which you can connect to from the CUCM.
(Tip: I use xlite as a ftp server for this purpose :)