Zenfone 8, Firmware 33.0210.0210.332, not rooted, occures always when roaming.
Since VoLTE finally worked with my home carrier H3G_AT ("3" Austria) after changing the SIM Card i still can't use VoLTE when I'm in any other country. Doesn't matter if it's EU or other countries like USA. Data connection always worked. Roaming, mobile data, data roaming and VoLTE is always turned on in the settings but i could never use VoLTE in any other country than with my home carrier in Austria. I know that with different phones all is working. So it must be an issue with the software or the phone. It's really exhausting that because of the missing VoLTE support regular phone calls are still not working in the USA!