When I assign functions to phone buttons if I write Label in Russian it’s stored empty. I have try with BLF and Speeddial. But if I change XXXXXXXXX.cfg file manually the Label is applied correctly. This means the phone support Russian labels and autoprovision works correctly.
Step by step - Click FreePBX Settings - EndPoint Manager - Brands - Yealink - template name - Available Phones (SIP-T23G). Assign BLF to Line Key1 with some extension number and Russian Label. Save Model. Click to phone model again - function and it’s value (extension number) assigned but Label is empty. If the Label is in English it’s saved correctly.