Do SIMs go bad?
 

I have s Telus SIM in a Telus handset (Galaxy SIIx, so not LTE which Telus didn't offer at the time) and the phone is intermittently losing the signal. I either get a circle with line through it in the status bar, or "SIM unregistered" (or something like that). At that point I can't make a call or...

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