My samsung galaxy s24 ultra says unregistered sim and sim 1 not allowed, when I turn the sim off and back on in the settings it works fine for a few minutes but goes right back to not working, I've tried factory reseting it, I've tried a different sim and I've tried putting my sim in another phone, the sim works in the other phone but not in mine, it was working fine with no issue up until yesterday when I woke up and noticed it wasn't working.
Same thing happened to my Ultra S22 ... I hope you have insurance because you need a replacement phone ... even with insurance , I had to pay $200 & something for my REFURBISHED replacement phone ... At&t told me it was RARE for this to happen , but I've seen quite a few other people have these "rare" issues ... š¤ Good Luck !
