Laptop is doing it again... somewhere around 1809 update, but can't say for sure that was it (since I use cellular sporadically).

I removed the SIM and inserted it into a spare cell phone. Could not make calls with it or access data.

Somehow the SIM is getting damaged or locked. Any clue? I tried unlocking it, but AT&T's website says it's not recognized to be unlocked. Perhaps I should put it in the Motorola phone again and try again.