Today we are upgrading our iPhone 4 GSM (SIM-Locked) to iOS 5 while preserving the baseband.  Preserving the baseband allows Gevey to continue to work without issue.  We have confirmed that this works with baseband 4.10.01, but should work just fine with others.  Please follow the steps very carefully.  If you are not careful you could easily upgrade your baseband, resulting in losing your preserved baseband and of course, your unlock.

Our setup:

iPhone 4 GSM

Gevey Interposer (We are using the standard one, not ultra Gevey)

Baseband 4.10.01

Macbook Pro

*** NOTES ***

After we upgraded to iOS 5 on our iPhone, we got this message in iTunes:

"The SIM card inserted in this iPhone does not appear to be supported"

We popped out our foreign SIM, put the original SIM back in (AT&T in this case), and setup the iPhone.  Then once it was setup, we put Gevey back with our German SIM and it worked fine.  

If you don't have an original SIM which your iPhone recognizes (i.e. the SIM that came with the phone originally), you probably shouldn't try this guide as we are not sure if you will be able to get it activated.

If you already upgraded to iOS 5 directly with iTunes, you probably upgraded your baseband and this will not work for you. You have to wait for an official unlock.

*** NOTES ***

Step 1

Download redsn0w 0.9.9b5.

Download iOS 5, you can do that here (Only for iPhone 4 GSM users).

Download iTunes 10.5 here if you don't have it already and install it.

Once you have all your tools, open up redsn0w. Then select "Extras".

Step 2

Click on "Custom IPSW".

Step 3

Select the iOS 5 IPSW that you just downloaded.

redsn0w will start working on the IPSW to create the custom one with the preserved baseband. This takes just a minute or two. 

Once redsn0w finishes, it will show this dialog. Please make note of the area indicated in red.  Press OK.

Step 4

Now we are ready to put your iPhone into DFU mode.  In redsn0w, select "Pwned DFU".

Turn off your iPhone 4 and plug it into the computer.  Do not click on next, as we will enter DFU mode by ourselves.  

Press and hold the Power button AND the Home button for exactly 10 seconds. Then release the Power button WHILE continuing to hold the Home button down.  If you correctly get into DFU mode, your iPhone screen should be completely black (NOT showing an iTunes cable on the iPhone screen) and this message should appear in iTunes:

redsn0w should also change to this screen: (make sure this screen appears before continuing).

If your iPhone is showing an iTunes cable on it's screen, you are NOT in DFU mode, you are in Recovery mode. Repeat the last step until you get into DFU mode.  If you try restore your iPhone and you are not in DFU mode, you will upgrade the baseband and lose your unlock.

If you are sure you are in DFU mode, please continue:

Step 5 - The Scary Part

• Open iTunes.
• Click on your iPhone in the left pane.
• Hold the OPTION key down and press the "Restore" button.
• iTunes will then prompt you to find the IPSW file. DO NOT SELECT THE IPSW YOU DOWNLOADED. You need to select the custom IPSW file that starts with NO_BB_ then select Open.

iTunes will check the IPSW file and then ask if you want to Erase and Restore your iPhone to iOS 5.0. Select Restore.

Now iTunes will attempt to extract the software and install it onto your iPhone.

IF YOU RECEIVE THE FOLLOWING ERROR:

The iPhone "iPhone" could not be restored. This device isn't eligible for the requested build.  

Click here for instructions on how to fix it, then come back and re-try step 5.

IF YOU DON'T RECEIVE ANY ERRORS:

Everything should be automatic at this point.  It will take 5-10 minutes to restore your iPhone with the custom iOS 5.0 IPSW.  Once that is done, your iPhone should restart and when it turns back on it will be ready to be setup.

Once you complete the setup, you can test your unlock with Gevey.

When you go through the Gevey instructions, usually you press "Accept", then wait for 1 bar to appear, then dial the "special" number.  With iOS 5, the 1 bar never appeared for us, so after we pressed Accept, we waited 15 seconds and then dialed even though it said "No Service".

It took us 3 tries to get Gevey to work.

Our Sim Locked AT&T iPhone 4 running baseband 4.10.01 and the public release of iOS 5 with Gevey Sim.

(For some reason the model shows as MC603DN)

Questions, thoughts, comments?