Sat. Sep 18th, 2021

How to Update iPhone 4, iPhone 3GS/3G Baseband to 06.15.00 with RedSn0w for iOS 4.2.1 Unlock

As we all know, the iPhone Dev team has released the Ultrasn0w unlock for carrier unlocks. This unlock will work for the iPhone 3G or iPhone 3GS with baseband 04.26.08, 05.11.07, 05.12.01, or 05.13.04. It will also work with iPhone 4 with baseband 01.59.00.

But sadly, If your iPhone’s baseband are not mentioned in above list, then you have to update the baseband of your iPhone to 06.15.00,  which is completely unlockable with use of ultrasn0w unlock.

So here is tutorial of updating your baseband to 06.15.00 with RedSn0w, so you can unlock your iPhone 3G/3GS 4.1.2.

Step 1: First read this , before doing anything ( important than unlock):



  1. There is no way to come back down from 06.15, and there’s no hiding the baseband version from Apple.  You’ll be voiding your warranty in a very obvious way.
  2. If some future baseband comes out with a critical fix, you won’t be able to update to it if it remains down in the 05.xx sequence (then again, you wouldn’t update to it if you wanted to keep your unlock anyway).
  3. Starting with FW 4.2.1 if you have 06.15 on your iPhone you won’t ever be able to restore to stock firmware (it will fail).  You’ll need to only restore to custom IPSWs (then again, if you’re unlocker you should already be doing that).

Step 2: Make sure you have the latest version of iTunes installed on your computer. If not, update iTunes.

Step 3: Make sure you have iOS 4.2.1 on your iPhone 3G or 3GS.

Step 4: Download RedSn0w 0.9.6 beta 5 as well as iOS 4.2.1 for your iPhone 3G or 3GS. (Download link)

Step 5: Launch RedSn0w and browse for the iOS 4.2.1 firmware you downloaded in the previous step.

Step 6: Once the IPSW is identified, click Next. RedSn0w will start preparing the jailbreak data.

Step 7: Now make sure you select to “Install Cydia” and “Install iPad Baseband”. A warning will pop up. Again, make sure you read and understand the risks associated with this.

Step 8: Make sure your iPhone is turned off and plugged in your computer. If it’s not, plug it in, then turn it off. Click next, and be ready to get your iPhone in DFU mode.

Step 9: Hold the Home and Power button together for 10 seconds. Release the Power button while still holding the Home button for a few seconds. Then let RedSn0w to run its magic.

Thats it! , You successfully updated the baseband of your iPhone to 06.15.00.


If your device is an iPhone 3GS with old bootrom, you won’t have any problem after that. If however it is a newer bootrom, you will notice that you iPhone shows the “connect to iTunes” logo every time you reboot it. It’s normal. While very inconvenient, it’s the way it is.

Again launch RedSn0w, plug your iPhone in and select “just boot tethered” just like the image below. It will kick boot your iPhone.