Got my ATT iPhone5 unlocked on switfunlocks but when I tried to use with a TMobile SIM card the phone works for 5 minutes and then goes to No Service. I took the phone to TMobile and we tried 3 different SIM cards and they all do the same. Took the phone to Apple Store and spent 2 hours with the Genius and they could not figure out what is wrong. The phone shows as unlocked and unblocked as the genius guy checked. He tried the SIM card on another iPhone from the store and phone works fine. Phone works fine with ATT SIM card. Any ideas what may be going on?