QUOTE(petpenyubobo @ Jan 25 2022, 10:38 PM)
These China branded phones very few of them made it into Maxis VoLTE and VoWifi compatibility list in time many will become eWaste soon even though thy support 4G networks.
Actually I poked around on some Xiaomi phones before in their modem config files
I noticed on older phones (Mi Max 2) only profile is for YTL (Yes 4G)
On some slightly newer ones (Mi A2), got profile for U Mobile
Only on rather recent phones that get updated (such as Mi 9T), got profile for Maxis.
On some newer models you can access a hidden config tool to force a profile from a different carrier and it might work.
Otherwise you're on the default "other" profile which might not work for your carrier.
For me on U Mobile and Mi Max 2, no VoLTE.
And no modem config tool either on this sadly.
Unless you want to go system file modifying and modify modem files (at your own risk), older phones are not gonna get volte sadly.
But with that said a part of the blame is also on the Chinese oems not updating their phones.