That is correct. My friend’s mobile carrier said they would disable 3G in December. Not sure why she only experienced the issue this week.
The Poco F3 supports up to 5G. I confirmed that its 4G bands are compatible with the carrier. AFAIK, this phone model was not officially released in Australia so it’s probably not on the carrier’s list of 4G compatible devices.
After entering the code to disable carrier check, the VoLTE icon shows up on the status bar and calls are now working as expected.
Damn you Nintendo.
https://lloydempty.itch.io/the-legend-of-zelda-era-of-decline