Samsung Galaxy S3 “SIM Card Not Found” error is most likely your fault.
I just spent 3 hours or so trying to figure out why my S3 suddenly stopped reading it’s SIM card. I must have jostled it when I was pulling the battery during a freeze up. The reason I was getting that error: I hadn’t seated it properly. The SIM cards are spring-loaded, designed to pop out after you push down on them. You gotta jam the card way down in the slot, farther than you can reach with your fingers until you hear it click or you feel it reach the end. No man’s land. It’s an act of faith. Do it, it’ll work better than fucking with your cell settings which weren’t wrong to begin with.
For all you Verizon users, a SIM card is this fucking tiny slab of metal and paper that is totally not necessary for CDMA devices since they can’t be unlocked to become GSM devices anyway. The rest of the world uses them to store settings and shit so you can swap phones and save your info, or something. I donno I’ve used Verizon for 15+ years. But I’m headed to Metro soon, fuck $80+/month