Everywhere else on the planet, in order for a device to be cleared for sale, that specific model undergoes heavy testing for regulatory compliance by a government agency.
“The specs said it was fine” is literally never going to be a valid legal defense, and making that argument will get you laughed out of court. Either it’s actually certified to be used as you’re allowing it to be used, or you get the hammer dropped on you, as you should.
That is simply not true. What you get is standards. Standards bodies exist. In this most recent debacle all that is needed is compatible bands and VoLTE to make it compatible.
If these two exist, then it works.
Don’t listen to me, here is a reference. https://www.whistleout.com.au/MobilePhones/Guides/Will-my-phone-work-in-Australia-carrier-network-frequencies
