Please tell us some basic information before asking for help:
Model Name: x00t
Firmware Version:438
Rooted or not:not
Frequency of Occurrence: android 9 and android 10 issue
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Lastly I got volte on android 8 on x00t after updating to android 9 and beta 3,4,5 volte is not getting for bsnl.
When I unlock my bootloader and flashed custom rom e.g. pe A10 and A11, volte is working.
But in stock roms bsnl volte is not working
Solve this problem fast