If you want to start updating your iPhone 3GS or iPhone 4 to iOS 5.1.1, I am sure that you will want to preserve the baseband in order to keep your device unlocked. Unlocking, for those of you who still do not know, is the process of removing all restrictions imposed by your carrier. In this way, you will be able to use your device outside your country without paying tremendous phone bills. You also can choose what carrier to use on your device even if you signed a contract with a specific carrier. Therefore, if you want to update your iPhone 3GS/4 to iOS 5.1.1, you can use various software programs while you preserve the baseband to keep your device unlocked.
I have to mention also the fact this guide is intended only for Windows users only. In the same time, before starting the update process, you should sync and backup your personal data using the iTunes or iCloud account to prevent errors during the process.
Here you have a step-by-step guide to update your device.
1. First, you need to download Snowbreeze and extract it on your computer.
2. Launch Snowbreeze and follow the steps indicated by the program. You will have to press the blue arrow in the right corner.
3. At this point, you need to browse for an IPSW and select the iOS 5.1.1 firmware. If you have not downloaded the iOS 5.1.1 yet, you have the possibility to start downloading it now.
4. When the program correctly identifies the firmware, click on OK.
5. Now, a new window will appear and you will have four possibilities to choose from. You have the Simple Mode, Expert Mode, iFaith Mode and the Baseband Preservation Mode. Choose the Baseband Preservation Mode.
6. The program will start create a custom firmware for iOS 5.1.1 while preserving baseband intact. The process might take a while and it can last up to 30 minutes before the file is saved on the your desktop. During this time, you will have the possibility to play Pacman, as a bonus received along with Snowbreeze.
7. When the process is completed, you will need to put your device in the DFU mode for all changes to take place. Now, follow the instructions that Snowbreeze offers you.
8. While starting with the DFU mode, the iTunes window should appear.
9. In the iTunes application, you need press the Shift key and click on Restore. Be very careful what firmware you choose. You need to select the one that has “snowbreeze_” as a prefix.
At this time, you will have your device updated to iOS 5.1.1 while preserving the baseband to maintain the unlock status of your device. If something goes wrong, you have all your data saved on iTunes or you can redo all the steps from the process anytime.