unlock Iphone 3gs Ios 5.01 baseband 6.15.00
hello my dear brothers
I bought an used Iphone 3gs with IOS 4.1 it was working well and accepting any sim card (without jailbreak and even cydia and SAM was not installed on it when working)
I upgrated it to 5.01 so now it locked and dosen't accept my sim card
if I will downgrade it again to 4.01 will it work ?
dos that mean my Iphone was official ?
please could you help me to unlock it with a way that preserve my battery when using it
sorry for my poor english
thank you very much