Hi there, My girlfriend's iPhone 4S is having the same problem as several people have reported over here, there is no mobile signal after upgrading to iOS7 and it only comes back after shutting down and starting up the phone several times... it's so annoying. I've performed a search in the forum and done some of the things suggested to try to fix it, to no avail. I haven't tried restoring iOS from scratch yet because she would lose all her data and apps so that's the last resort. Is there any "easy" solution to this? Could It be that the SIM card is somewhat malfunctioning and it's not a software problem?