I've tried to Google it but had difficulty finding a concrete answer for Australia in 2022. My idea is to port my mobile number to a relatively stable/well known enterprise VoIP provider and use a 4G equipped tablet as a phone, always with me for the more advanced features and larger screen size. I know I could hotspot a tablet but don't really want to carry two devices everywhere.
Issues I've thought about so far: Text messaging (which I actually do more than call), lack of calling facilities (would need a headset or have to use loudspeaker), camera not as good as my phone, might not always be pocketable (I was thinking on the smaller tablet end like iPad Mini or smaller), VoIP provider might disappear, additional cost of a mobile data plan and VoIP plan, connectivity with devices particularly smart watch.
If you've any thoughts for or against or have done something similar I'd love to hear from you. This could all be a very bad idea that blows up later or it could be neat.
I would buy samsung fold instead or some other similar device