Bidroh, SIM would not be an issue here (you can cut with scissor or buy the SIM-cutter ..i would personally buy SIM cutter because it comes with the adapter that you can switch to regular SIM phone) If you have the earliest iphone 4 (ie. with firmware 4.0.1) then you are lucky meaning that can be jailbroken and unlocked. Newer than that (4.1 and 4.0.2) cannot be jailbroken and unlocked at this time.