With the iPhone Dev Team’s inability to find a usable baseband exploit for the iPhone 4 and release a stable unlock for basebands 2.10.04, 3.10.01, and the newer 4.10.01, several alternate iPhone 4 unlock solutions have sprouted.
The first option was the Gevey SIM Interposer. Similar to a Turbo SIM, the Gevey SIM Interposer worked by adding a EEPROM chip to your SIM card. You would then call 112 from the Emergency Dialer screen. Once the call connected you would hang up then toggle Airport mode on and off. When the network connection resumed, your iPhone 4 would be unlocked.
This method would provide a “tethered” unlock, meaning that after you reboot your iPhone, you would need to repeat the unlock process. While the legality of the unlock solution was questionable at first, Dev Team member, MuscleNerd, confirmed the unlock method was illegal. Read More