Hi,
I think you can record a whole new language using the... 'Prompt development kit'. Which you need to order from Ericsson.
Its a lot of work to produce a new language... have a listen to the wav files on the OB DVD
\Telephony Server\Install\Server\Prompt\U_law_8k\Prompt00.WAV
This is over 40 mins of speech that has to match the system functions, then you need to do the default Call Processors, and VIM.
You can change a few prompts via a phone when logged on with the admin mailbox (9999).
Regards
Isinor