Question Please help me look for the correct firmware for a downgrade for s21+

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Nov 28, 2021
Samsung Galaxy S21+
I own an unlocked S21+ with SD888 and I want to downgrade from One ui 4 to One ui 3.1 since samsung doesnt support VoLTE in One UI 4
I need to understand what carrier's firmware should I download to flash through Odin. Does i t make any difference or not?
Please help. ( screenshot atta
ched below)


Nov 28, 2021
I am in the same boat, I have S21+ US version with snapdragon and I came to India on a business trip and try to use JIO sim, which is a VoLTE, and as soon as I inserted the JIO Sim the VoLTE option disappeared.

I used Samsung Band Selector app to see the actual configuration and I see the VoLTE has been OFF and grayedout and unselectable/unchangeable. As soon as I insert an American carrier RedPocket SIM, the Volte is automatically on and I can toggle it.

I reported the issue to Samsung Beta team and surprisingly they have responded and suggested a solution. Here is their response, but don't know how to implement it

Any help is greatly appreciated....


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    Ahhh, I see.

    Just out of curiosity, have you tried resetting network settings?

    Settings > General Management > Reset > Reset network settings