This tutorial will teach you how to unlock iPhone 4, using a Gevey SIM on the iOS5.
In order for your Gevey SIM to work on iOS 5, please make sure you have the latest version, using a custom firmware created with Redsnow 0.9.9b5 (iOS 5 jailbreak). Using this tutorial you will keep your original baseband so it could be unlocked with the Gevey SIM. If you have another iOS 5 baseband, the unlock with Gevey SIM will not work on your iPhone 4.

After you have successfully installed the iOS 5 custom firmware, you have to carefully follow… Continue to Gevey SIM on iOS 5