Unlock iPhone 4 4.2.1 : How to Do it Safely

To unlock iPhone 4 4.2.1, you must first do the jailbreak process. Once your iPhone is unlocked, so that the unlocking process will be a piece of cake. When it comes to open the Apple smartphone, which depends on the band performed by the device. So check out the band before you unlock the iPhone 4 4.2.1.
For the iPhone 4 4.2.1, the UltraSn0w 1.2 is the right choice for the opening band iPhone 1:59:00 4. If your iPhone 4 does not have the kind of band, you must update the device or search for a new version of UltraSn0w. In the meantime, if this is your band, you can start Cydia and search for UltraSn0w. Then download the application opens. When you have completed the download and installation process, restart the iPhone 4 and insert your new SIM card, because they have managed to unlock the iPhone 4 to complete the process.
Please note that you need to Jailbreak iPhone 4 before opening. First, download the jailbreak program you want on your computer. Connect the iPhone 4 on your PC and remember to turn off. Jailbreak run the program follow the instructions carefully. Choose your iPhone 4 to firmware IPSW file. After a few seconds, hold the "Power" and "Home". This means that you put a iPhone 3G in DFU mode programming. The iPhone will reboot and now you can use Cydia iPhone unlocking and create 4 processes.