snom M300 DECT XML Template

[ltechnet]

Hello
i want to change the Name on the Display on our SNOM M25 on a SNOM m300DECT Base to the Surname of the user.
And the Tone Set to SWI (Switzerland) which is supported by the firmware but 3cx did not integrate it on the admin page.

I found several copies of the snomM300.fxs.xml
/usr/share/3cxpbx/skel/Data/Http/Templates/fxs/snomM300.fxs.xml
/var/lib/3cxpbx/Data/Http/Templates/fxs/snomM300.fxs.xml
/var/lib/3cxpbx/Instance1/Data/Http/Templates/fxs/snomM300.fxs.xml

Which one i need to modify?
Or is there an other way? (no i dont want to exchange the names in the extensions)

Thanks in advance