Downgrade Baseband 4.11.08 to 4.10.01 of the iPhone 4 on iOS 5.Unlock baseband 4.11.08 is not possible till now .Did you upgrade to iOS 5 with the stock IPSW file without taking in the consideration that it will update your baseband to 4.11.08 which not unlockable with the Gevey SIM or Ultrasn0w. The solution in this case is to downgrade the Baseband 4.11.08 to 4.10.01which is lockable with the Gevey SIM .And here’s how to downgrade Baseband 4.11.08 to 4.10.01.
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One of our readers has tipped us with this way to downgrade Baseband 4.11.08 to 4.10.01, and he told us that it works 100% .
Required downloads to downgrade Baseband 4.11.08 to 4.10.01 :
Download iTunes 10.4.1
Download iOS 4.3.5 for iPhone 4 .
Download TinyUmbrella .
Download iOS 5 for iPhone 4 .
For Mac users Download Redsn0w 0.9.9b5 .
For Windows users Download Sn0wbreeze 2.8b8 .
Download iTunes 10.5 for windows and mac .
How To Downgrade Baseband 4.11.08 to 4.10.01 :
Step 1 : Downgrade iTunes 10.5 to 10.4.1, check how to from here .
Step 2 : Put your iPhone 4 into DFU mode :
Hold the power button quickly and then while doing so you have to hold the home button too. After holding for a few seconds let go of the power button but keep pressing on the home button until the screen becomes black .
Step 3 : Start iTunes 10.4.1 and click on your iPhone 4 icon then click shift & restore (For Windows) or option & restore (For Mac) and point the stock iOS 4.3.5 .
Step 4: Wait until iTunes verify the iOS 4.3.5 on you iPhone and once completed you will need the official SIM card to activate it or you can use TinyUmbrella to confirm that your baseband is 4.10.01.
Step 5 : Start Sn0wbreeze 2.8b8 (Windows) or Redsn0w 0.9.9b5 (Mac) to build custom ipsw . Check how to do it from here .
Step 6 : Install iTunes 10.5 again .
Step 7 : Put your iPhone 4 into DFU mode again, and start iTunes 10.5 and click on your iPhone 4 icon then click shift & restore (For Windows) or option & restore (For Mac) and point the custom iOS 5 that you have built in step 5 .
Now your baseband will be preserved while running on iOS 5 and you can unlock it with Gevey SIM
Step 8 :Install the Gevey SIM on your iPhone 4 :
1:Insert the Gevey Sim in your iPhone 4 as shown below :
2:Turn on your iPhone 4 and wait for the Sim welcome menu , then Click Accept
3: Wait for 15 seconds , Then Call 112 and hang up within 2 seconds .
4:Go to Setting and Turn on the Airplane mode and turn it off right away.Now you will see “SIM Failure” message on your iPhone and then you will see “No SIM Card Installed” .
5:Now again you have to turn on the Airplane Mode and turn it off right away again until the “No SIM Card Installed” message shows up. Now you will see ‘SIM Failure’ message and after few seconds the signal will show up.
Now your done, enjoy your unlocked iPhone 4 on iOS 5.
Note : We didn’t have time to test this method, so if you want to do it, do it on your own risk, and we are interested to know if it works, so please inform us via comments below .
Stay tuned with us for another way to Downgrade Baseband 4.11.08 to 4.10.01 or may be unlock Baseband 4.11.08 by new tools by the iPhone hackers .