I didn't investigate a lot but it seems french prompts are incomplete and I talk about core asterisk prompts.
So I guess there are not the official ones, right ?
If you get them from asterisk-france, note that they are for 1.2 version not 1.4.
I will have a look soon to this issue and will let you know more details.
With asterisk 1.4, Digium provides indeed french prompts for core and extras and they can be downloaded from digium. These sounds may be freely distributed and are free for use with Asterisk. You have to pay only if you need custom prompt with the same voice.
My question was:
Why elastix don't use these prompts ?
Currently, the provided fr prompts cannot be used as some are missing even core messages.
So it seems better not to include at all french prompts or use complete ones from digium.