Update on my situation:
Yes iodeOS team got back to my support request and pointed out the APN name settings.
Once I got that setup, I can now send and receive 5G calls but wi-fi calls still don’t work at all.
At least I have functionality now as I’ve set calls to use 5G only and that works. But it’s very sad that Wi-Fi calls don’t work. So is this a hardware issue then???
I’m using amaysim - which is part of the Optus Network in Australia - so maybe Optus are an issue also?
Update: Optus is not the problem - this BraX3 Telco Compatibility – Rest of the World says fully supported