Upgrading your iPhone 4 to iOS 4.1 will update its baseband from 01.59.00 to 2.10.4 and baseband 2.10.4 is not unlockable at the moment. PwnageTool is an option to preserve iPhone baseband but at the moment it doesn’t support iOS 4.1. Second option to preserve baseband of iPhone 4 is TinyUmbrella, using this utility you can save SHSH blobs of your iDevices and also preserve iPhone 4 baseband 01.59.00. Lets see how to update iPhone 4 to iOS 4.1 without updating baseband.
Note: I have tested this guide on my iPhone 4 and working fine, If you are brave enough then you can try it at your own risk.
Connect your iPhone 4 with computer and save SHSH blobs, check this link how to save SHSH blobs iPhone 4.
- On TinyUmberella click the “Start TSS Server” button and keep it running.
- This will kill iTunes.
Run the iTunes and make sure TinyUmbrella’s TSS Server is running which we have started in step-3.
Hold the “Shift” key on Windows or “Alt” key on Mac then click on “Restore” button on iTunes and choose iOS 4.1 firmware file that you have downloaded in step-1.
iTunes will start the iOS 4.1 upgrade process on iPhone 4. You may see the following message, don’t worry about it just click OK.
When iTunes finished the upgrading process close the iTunes.
Go back to TinyUmberella and hit the “Kick Device Out of Recovery” button.
You are done! you successfully upgrade iPhone 4 to iOS 4.1 without updating its baseband.
How to jailbreak iOS 4.1 on iPhone 4, iPhone 3GS, iPod Touch 3G, iPod Touch 4G.