FreePBX 13 language setting for PJSIP trunk

Hi,

How setup language for PJSIP trunk?

FreePBX 13.0.35 - Asterisk 13.6.0

What do you mean exactly?
FreePBX 13 has the menu "Sound Languages"
There you can create the language with your language code.

After this you can set your default language global for everything on your freepbx

I did so. But at an incoming call, language of messages remained english.