My Android phone was frequently losing the connection to the SIM card, causing me to miss calls and text messages. Several online forums point to battery and system monitoring apps as causing the problem. I had one of these apps installed, so I uninstalled it, but the problem remained. I even tried resetting my phone to factory defaults, but that did not work either. The solution turned out to be really simple. I found a forum a few months later that suggested removing the SIM card tray and placing a small piece of tape over the back of the SIM card to hold it more securely in the tray. I did this over a month ago and have not had the error happen since then.