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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)


Assistant Forum Admin
Staff member
Jan 30, 2006
NSW, Australia
Samsung Galaxy Note 20 Ultra
Who said OneUI 4.1 doesn't support VoLTE? It DOES support it. It's a standard feature.

When you updated, did you download the firmware and flash manually? It sounds like you may have flashed the wrong region firmware, if VoLTE isn't working.


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