You can preserve old baseband on iPhone if you are looking for to upgrade your iOS to 5.1.1 and afraid of losing unlock. This method is easy and all you need is to download latest RedSn0w version. With release of couple of tools from iPhone Dev team it is possible now to do many hacking things with iOS gadgets. Among these tools is RedSn0w 0.9.12b1 which was developed to jailbreak iOS 5.1.1 untethered. Also it can restore SAM activation ticket (in case you use SAM unlock) and update to iOS 5.1.1 preserving old baseband on iPhone. Preserving old baseband is very important move for those who unlocked their phones and didn’t want to lose it. So if you use Ultrasn0w or Gevey sim to unlock your iPhone this guide is for you. You can use Sn0wbreeze 2.9.5 to preserve old baseband while updating to iOS 5.1.1 as well but this tool is only for Windows. In case you are Mac user there is a possibility to preserve old baseband with Pwnagetool 5.1.1. However now you have RedSn0w 0.9.12b1 and you can do the same on both Mac and Windows. You can use this tool to build custom iOS 5.1.1 IPSW and restore to it using latest version of iTunes. It allows you to restore your iPhone without updating old baseband.

Requirements

• iOS 5.1.1 firmware (download here)
• RedSn0w 0.9.12b1 (download here)
• Latest iTunes (go to Apple official site to download)
• iPhone 3GS, 4

How to Preserve Old Baseband on iPhone Using RedSn0w 0.9.12b1

Note: There is no tool yet that can downgrade iOS 5.1.1 so thing twice before we start. Step 1. Open RedSn0w and go to Extras => Custom IPSW and point your just downloaded iOS 5.1.1 firmware. Step 2. If you are iPhone 4 user building of custom firmware begins automatically but if you are iPhone 3GS user RedSn0w will asks you which bootrom has your 3GS, new or old. To find out which bootrom is on your iPhone just look at the serial number where the third number means a last number of the year and then fourth and fifth numbers means week of that year. For example: 86147 where 1 is 2011 and 47 is forty seventh week of 2011 and this means that this iPhone 3GS has new bootrom so tap Yes. Step 3. Redsnow are building custom firmware so you need to wait till it finishes the process. It creates IPSW preserving old iPhone baseband and you can find it on the directory where is located iOS 5.1.1 firmware or on your desktop. Step 4. Now you need to restore your iPhone through iTunes but first you must put your iPhone in DFU mode. Here are instructions if you need or go to Extras => Pwned DFU and follow on screen instructions. Step 5. After you enter DFU mode open iTunes and holding Shift on Windows or Option on Mac press restore and select custom IPSW file with such title:

NO_BB_iPhonexxxxxxxxxx_Restore.

Step 6. Now wait till iTunes finishes restoring and enjoy you preserved old baseband on iPhone. Note: If there will be error 3194 go here to fix it. That’s it. Now you can enjoy old baseband on iPhone 4 or 3GS. If your baseband allows you to use Ultrasn0w follow easy directions to unlock iPhone using Ultrasn0w 1.2.7. That is the easiest way to unlock your iPhone. But if your 3GS is on 06.15.00 baseband and it doesn’t unlock then open redSn0w again click Jailbreak => Install iPad baseband => Next. Warning: Using iPad baseband your GPS will be corrupted and your baseband chip can be corrupted too. Also if you're using Gevey Sim and don't know how to activate your iPhone with it use this link to do it quickly. I hope this post was useful for you and you have no problems with preserving old baseband on iPhone 4, 3GS. But if there were some then let me know using comment form below and I'd try to help you.