Hello friend! hope it can share u some knowledge:
For the V100R006C00, V100R006C01, V200R006C00, V200R006C01, and earlier versions:
Load a software version. The C0X version determines the voice protocol used on an ONT: SIP is used if X is an even number and H.248 is used if X is an odd number.
For the V300R012C00 and later versions:
Choose Voice > SIP/H.248 Protocol Conversion from the main menu on the web page.
Good day!