Update to iOS 4.2.1 While Preserving Baseband 01.59.00 on iPhone 4

For those of you who own an older iPhone 4 there is a method which you can easily use to upgrade your OS to iOS 4.2.1 while keeping your baseband the same that is 01.59.00. This baseband is unlockable using Ultrasnow 1.2.

The method is only to be used with iPhone 4 (with an older baseband), and is not to be used with any other iOS device.

Here is how you do it:

The very first is to download the iOS 4.2.1 firmware ISPW files. The link to the download can be seen below:

Now, navigate to the following location:

  • · C:\Windows\System32\drivers\etc\

Open the hosts file using Notepad or any other reader which might read the file. Once the file is open, add the following command syntax to the very bottom of the file. This is done to trick the Apple server into thinking that the iTunes is watching Apple servers, while in reality it watches Saurik’s servers (Cydia).

  • gs.apple.com

Once you have added the above command to the “hosts” file, save it (look at the screenshot below).

Now, the third step involves you opening iTunes and clicking on your iOS Device.

iTunes will now prompt you to choose the location of your firmware files. Navigate to the area where you previously saved the iOS 4.2.1 firmware files. Select the ISPW file and click on “Open”

Now, just sit back and relax while iTunes does the work. Also, you may encounter a “1013″ error, if you do so, ignore it as it happens due to some technical error, but there is really no harm done.

Now, since your iPhone will be stuck in recovery mode, you’ll have to get it out of that mode. To do so, download TinyUmbrella from the link given below and click on the “Exit Recovery Button” inside the program, once you run it.