I tried that method on my daily GS290. So there was a SIMcard installed.
I think that is a great nuance that I needed to share.
Perhaps somebody can still shine some light on the VOwifi and VOLTE subject
these are just setting switches and are not a guarantee it really will work.
Still I think the gs290 very likely does VoLTE/VoWifi in its target market (EU) at least in stockrom and if it fails to do so in a customrom could be debugged for why it fails to do so. Its very close sibling the Volla Phone was said being able to do so. But I don’t have the device to put weight behind that statement.
I tried to translate from the website @tcecyk suggested, and what I understood (which might be wrong ) is that, in 2021, a user complained about issue with wifi, and another answered that his GS290 had /e/OS, that did not support vowifi …
Perhaps things have changed since then, so, if anyone can tell me whether GS290 can support vowifi and volte, that would help me a lot.
until now i have NOT found any way to make Wifi-Calling run on GS290. Sorry.
I tested it for some hours. (The GS290 says it is “ready for Wifi-Calling”, but it complains about “no connection” when try to register WiFi-Calling.)
VoLTE works fine. From my point this is the more important point.
Thank you very much @User100 for your efforts and support.
VoWifi is an important feature as well to me (when in areas of poor coverage / indoor, I can call and send / receive SMS by using the wifi), which is a reason why I have waiting for some feedback before buying the device…
I do not want to bother you any longer, let’s see if any other users have some feedback.