A lot of good GSI ROMs are available. Everything works fine except VoLTE. VoLTE does not work with almost every gsi roms for exynos devices.
Though it was primarily circulated that the voice calls doesn’t work on the non VoLTE 4G roms. It’s because Samsung use proprietary IMS implementation (Which is used by VoLTE/VoWifi/ViLTE etc). The codes aren’t available in public so developers can’t enable/port over this function. Here are a few steps one can follow to use Jio sims in any non VoLTE roms.
- Download and install Jiocalls App
- Open Jiocalls and grant all the access
- Configure JioCalls
- Try calling or messaging any of your friend