how can I sim unlock Cricket Galaxy S4 (SCH-R970C) or flash other gsm network
I have a Cricket Galaxy S4 (SCH-R970C) with baseband version R970CVVUAMI3
I tried to sim unlock my phone through this method http://forum.xda-developers.com/show....php?t=2283068
I did follow all the steps but when I insert another sim (T-mobile), I got an "Invalid Sim" pop up message.
I am thinking of trying this method, but I don't know if it is safe to do so.
is there any way to back up my phone(baseband, etc...) just in case everything screwed up during this process?