How to add an UM language pack
There is a list with all available UM Language Packs for Exchange Server 2007, you can check this out at: http://technet.microsoft.com/en-ca/exchange/bb330845.aspx
After downloading the file we can add it to our current UM server, using the following command:
Setup.com /AddUMLanguagePack:<Language Code-Country> /S:<source directory where the Language Pack was installed>
In the figure below I'm installing Canadian French support to the UM Server, after that we can start play with Auto Attendant and Dial Plan using the new language.