Changing the Language for the Phones in the UC
Download the UC500 IP Phone Localization @ https://upload.cisco.com/cgi-bin/swc/fileexg/main.cgi?CONTYPES=UC500
Save the file in C:\Program Files\Cisco Systems\CiscoSMB\Cisco Configuration Assistant\appdata\phoneloads\
Which is specified in the CCA on Configure -> Telephony -> Region : Location of Language Files
Select the Language you need to use, and click apply
Setting the Voice Mail Language
Using WinRAR or similar software, extract SCUE-UC520-7.0.3.zip file from UC520-7.0.3.zip
extract all the contents of SCUE-UC520-7.0.3.zip file into any folder on CCA PC. Copy the cue-vm-de_DE-langpack.ise.7.0.3.prt1 that is available @ https://upload.cisco.com/cgi-bin/swc/fileexg/main.cgi?CONTYPES=UC500 to the same folder.
Go to Maintenance > Software Upgrade window. Select UC500 you want to localize, and
click “Upgrade Settings.” Select cue-vm-k9.ise.x.x.x.pkg file, click Open
Click Yes and then Upgrade
And wait for 40 min
Until everything is completed
And save the configuration!