Chosen Solution
My s4 normally reads my SIM card no problems, until about a month ago, when it started intermittently losing access to the SIM card, blocking it from the network and preventing calls. Sometimes a reboot would make it work again for a bit. I tried a few other SIM cards with the same results. The strange thing is I find if I remove the phones back plastic chassis exposing the main board the phone reads my SIM card no problem, and will work continuously until I put the back chassis back on. I also found if I carefully put the back chassis back on the phone, but leave one side not fully clicked in place, the phone still reads the SIM card OK, until I click the last few bits in place. I bought a replacement back chassis and found that the phone works properly with it fitted, using other SIM cards. But once I put my own SIM card in it wont read it properly again. My SIM card works fine in other phones. Any help or info much appreciated.
Very odd. I just had this same thing happen on my iPhone 5. What carrier do you use? I use a Verizon reseller and a month or so ago, it started giving me pop-ups every couple hours that said “No SIM” or “Invalid SIM” and wouldn’t let me access texting, calling, or data (Wifi still worked) and would stay like that until I restarted. I contacted the Verizon reseller and they said I needed to buy a new SIM (just got this one in the last 6 months). I didn’t want to pay for that so I just waited and it hasn’t done it again in at least a month. How long has this been going on? Have you checked if the chassis pushes on the SIM or board? I don’t know much about Samsungs so pardon my question, can your phone tell if the cover is on or not? If not then it has to be a physical problem since taking the cover off helps. You could also try contacting Samsung, your carrier, or wherever you bought your SIM; probably won’t help but it’s worth a try. Let us know if you figure it out.
