Xperia 10 III (XQ-BT52) VoLTE issue in Australia

bought my phone from kogan and after enduring the '3G is shutting down message' before every phone call, i decided to flash the firmware to an SEA region.

after a bit of fiddling with XperiFirm and newflasher i was able to update the firmware without wiping my phone and am now using the latest 62.2.A.0.533. i typed in * # * # 4636 # * # * to see if the option to enable volte was available. sadly it's still greyed out.

i googled a bit more and a few people suggested calling the carrier to get the provisioning enabled. i got in touch with Boost and was told it was simply not supported on my device. i don't know if there's anything left to try and i guess i'll have to wait and see. some people on the internet say it'll be fine when 3G is switched off, some reckon emergency numbers might be affected, some reckon it'll be fine with 4G. it's all a bit disappointing and i'm not sure if it's xperia's decision to hardware lock the setting on this model or whether something else is the reason. i do like the phone but this has me questioning whether my next one will be another xperia. any ideas?