Having a weird problem with my iPhone 6, fresh out of warranty. For no good reason (didn't drop my phone or anything like that), I lost connection to my carrier (AT&T). Wifi was working fine. Multiple reboots, network resets, flight mode toggle, SIM reseating (even SIM switch at the AT&T store) didn't fix the problem. I was on iOS 9.2 and had 9.3 already downloaded, so the AT&T guy suggested applying the update. I updated to 9.3, and upon reboot I had a signal and connected to my carrier. Yay ! Except, a few hours later I checked my phone and had the same problem again. Again reboots / resets / checking for carrier updates etc to no avail. I read online that some people had this issue fixed by dropping their phone. I wasn't about to do that, so I banged my phone on my knuckles a couple of times, and after yet another reboot, it connected to my carrier, and has been working since (last night). What gives ? Is there a connection inside the phone loose or something like that ? I'd prefer a more permanent fix. TL;DR: Hitting my phone (temporarily ?) fixed my connection problem.