How to Update Your iPhone 4 Without Upgrading the Baseband (Windows) 4.2.1 with Help of TinyUmbrella
Since the new GreenPois0n RC5 iOS 4.2.1 Untethered Jailbreak tool by Chronic Dev Team is out all iPhone 4, iPad and iPod Touch owners / users can now jailbreak their devices even on the latest iOS 4.2.1
For those of us iPhone 4 users who are still on 4.0.1 or 4.1 and still would like to keep our unlock the basebands must remain at the same version or the iPhone will be bricked.
If you will update your iPhone to the latest iOS 4.2.1 your basebands / Modem Firmware will be updated as well and you will not be able to unlock your iPhone for the use on other carriers such as T-Mobile, Fido, Rogets, etc.
This tutorial will show you how to upgrade your iPhone 4 to 4.2.1 without upgrading its baseband using TinyUmbrella.
Please Note: This ONLY Works with the iPhone 4!
Download TinyUmbrella from here Also make sure to download the iPhone 4 iOS 4.2.1 which you can find here. in our Firmware Download Section. (NOTE: Please make sure you download the right file/firmware for the right device)
If you do receive an error, DO NOT continue. Your restore will not work if the TSS server cannot be started.
iTunes should give you error 1013. This is what we wanted, as it notes the baseband has not updated Click Ok and close iTunes.
If you get a 16XX error then try entering DFU and go to step 5.
If your restore does NOT end in a 1013, it means your baseband was updated. This is likely because you did not have the TSS server running OR you updated without TinyUmbrella OR you are working with a device OTHER than iPhone 4.
You are now ready to follow our Greenpois0n tutorial which will jailbreak your device and bring it out of DFU mode. **Note: You do not need to put the device into DFU mode after press the Jailbreak button in Greenpois0n as we have already done this
Your iPhone will now be on 4.2.1 with the 1.59.00 baseband! (Which means you can now unlock using ultrasn0w Click Here for Detailed Unlocking Tutorial)