My current OS is 4.1. that wht i mistakenly did. now my phone is locked and wid unsupported SIM. nothing i can do. i'm from bangladesh. my prevous OS is 4.0.2 and dat was unlocked and jailbroken. if i perform 'erase content and settings' on iphone what will happen then? will it delete my current firmware, baseband? after deleting that may i able to restore to 4.0.2 or any other iOS? what will happen in os and base band. will i be able to jailbreak older os? Plz some one let me know. thank you.