1. AC Question's Avatar
    I bought a Galaxy S4 from carphone warehouse which is unlocked , but ever now and again it says (mobile network will be unavailable until you restart with a valid sim card inserted ) I have a 02 sim card in it and it switches on and works
    01-21-2015 03:53 AM
  2. belodion's Avatar
    It may be a bad SIM or a problem with the SIM tray. Take it to O2 and ask their advice.
    Also, a Cache Partition wipe may be worth trying.

    Posted via the Android Central App
    01-21-2015 07:17 AM
  3. Jazz S1's Avatar
    I am a new guy at it also and my s4 started saying restart sim i tried rebotting etc and was going to get some to root it etc as it was driving me crazy
    But i kept looking at all solutions until i was came acrossa guy who cleaned the sim and sim boot with rubbing aclhol i had some of the spray bottle of rubbing alchol right next my computer i opened the phone took the sim out sprayed 2 squirts of rubbing alchol and and blew the excess out right away i inserted the Sim and its as good as new
    I had asked my indian enginess friend they said change the sim slot etc etc
    Anyway i was so lucky i dont know but it worked for me
    01-24-2015 09:20 PM

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