How to Unlock iPhone 4 4.2.1 after Jailbreak with Greenpois0n RC5 Baseband 1.59.00

STEP 1: Download TinyUmbrella [You must be registered and logged in to see this link.].

STEP 2: Open TinyUmbrella then click on "Start TSS Server"

STEP 3: Open iTunes.

STEP 4: Now, Click on "Restore" NOT "Update"

STEP 5: Now you will get "Error 1013" which means that your baseband has been preserved.

STEP 6: Exit iTunes.

STEP 7: Now you have to jailbreak your iPhone 4 with the Greenpois0n RC5, follow our guide [You must be registered and logged in to see this link.].

STEP 8: Finally you can unlock your iPhone 4 running baseband 1.59.00 using Ultrasn0w 1.2, follow our guide [You must be registered and logged in to see this link.].