As time is getting closer to the release of untethered iOS 4.3.1 jailbreak tool, many of our loyal reader start asking us how they can update their iPhone 4’s to the latest firmware iOS 4.3.1 without updating baseband to the latest one so they can unlock their device with ultrasn0w. So here is the simple guide on how they can update their device while preserving their basebands.

 

Follow the below given steps carefully:

Step 1: First of all you need to download TinyUmbrella and iOS 4.3.1 (Direct Link)

Step 2: Now, Connect your iPhone 4 via USB and run the downloaded TinyUmbrella, it should automatically detects the device and start showing the current firmware.

Step 3: Before proceeding to the next step, must check that you have save your SHSH blobs for iOS 4.3, if not then click on “Save SHSH” to save SHSH blobs offline.

Step 4: Now Click on “Start TSS Server” and you’ll see “TinyUmbrella’s TSS Server is running” under the Log tab. This will automatically force iTunes to quit but keep TinyUmbrella open.

NOTE: If you receive an error here, DO NOT continue. Your restore will not preserve baseband if the TSS server cannot be started.

Step 5: Now again open iTunes and navigate to the restore option, now press and hold the Shift/Option key and click on restore, it will prompt you for iOS 4.3.1 .ipsw file that you have recently downloaded, select the file.

Step 6: During the process of restoration iTunes may throw you an error “1013”, just ignore it and click ok and close the iTunes.

NOTE: if you get a 16XX error then first enter DFU mode and then restore.

If your restore does NOT give you “error 1013?, it means your baseband was updated, because you did not carefully read the warning in Step 5.

To enter DFU mode, hold down both Power and Home buttons for 10 seconds, then release the Power button while still holding the Home button for 5 more seconds.

 

Step 7: Now download fix recovery for 4.3.1 via links below and run it. (You’ll see some scrolling text on your iPhone 4 when it’s running)

 

That’s it, Congratulations you have successfully updated your iPhone 4 to the latest iOS 4.3.1 without updating iPhone 4 baseband. Now you can unlock the old baseband with ultrasn0w