Users who have iPhone 4, iPhone 3GS or iPhone 3G over jailbroken iOS 5.0.1 and want to unlock through recently released Ultrasn0w 1.2.5, must follow guide below to know about unlock process.
Unlock iPhone over iOS 5.0.1 using Ultrasn0w 1.2.5
Your iPhone over iOS 5.0.1 must be jailbroken to work with Ultrasn0w 1.2.5. Check links to guides below to jailbreak iOS 5.0.1, if you iPhone is not jailbroken already.
Sn0wBreeze 2.8 b11 to Jailbreak iOS 5.0.1, Ac1dSn0w Jailbreak tool for iOS 5.0.1, RedSn0w 0.9.9b9b iOS 5.0.1 Jailbreak
On your iPhone tap on Cydia
Tap Manage > [...]