i bought SAMSUNG GALAXY S4 SPH-L720 witch rom cyanogenmod 11 nightly. Something is wrong, galaxy has simlock and seller says to me, that is unlocked. I can make calls but when someone called to me, nothing happened. So i decide that I want back to stock rom. But i don't know the number of previous version android. Cyanogenmod 11 is based 4.4.2 android, so i must install stock rom 4.4.2? I prefer install older android, i want to unlock simlock. My modem is L720VPUAMDC.