so i upgraded my 3gs to 5.1.1 and jailbroke/unlocked, and downgraded modem firmware to 05.13.04 .
my phone shows t-mobile now on top next to a full bars signal. but however, every single time i make a phone call or receive a call,as soon as i hang up the service gets lost and starts "searching".
it usually finds signal again within a minute. but it does this every single time.
im guessing the problem has something to do with the ICCID saying NO SIM.
also the carrier says "carrier 12.0" dont know if this means anything.
i need help on how to fix this problem. i dont know whats wrong and/or of i missed any steps.