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iPhone Compatible Cable
iTunes
Gevey Blue Turbo Sim

Have you stupidly upgraded to ios 5 without knowing it upgrades your baseband to 4.11.08, You can still unlock Hopefully.

You will be downgrading your baseband in this tutorial.

1. Download and install iTunes 10.4 or earlier. You will need to remove iTunes 10.5 first.

2. Download iOS 4.3.5 IPSW for iPhone 4 from Apple Website.
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3. Put your device into Recovery Mode aka DFU Mode.

4. Connect to iTunes and it will say that your device is in recovery mode and needs to be restored.

5. Then click shift+restore (Windows) or option+restore (Mac). Select the IPSW you just downloaded.

6. iTunes will verify with Apple server and begins restoring your device. Once completed you will need the official SIM card to activate it.

7. Now download custom iOS 5 from here. Reinstall iTunes 10.5 in the meantime.
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8. Download latest redsn0w from the Dev Team’s website or from this link.
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Start redsn0w, go to Extras > Pwned DFU, This allows your iPhone to accept custom firmware. If you don’t do this, you will get error 1604, 1600(other error codes)

9. Connect your iPhone to your computer.

10. Click shift+restore (Windows) or option+restore (Mac) and select the custom iOS 5 IPSW you just downloaded.

This time your baseband will be preserved while running on iOS 5 and you can unlock it with Gevey Blue Turbo SIM.
Again – do it now because once Apple stops signing iOS 4.3.5, you will be stuck forever!

THANKS FOR READING AND I HOPE IT WORKS FOR ALL OFF YOU, PLEASE LEAVE A THANKS IF I HELPED MUCH APPRECIATED.

you cant do this. i tried.

apple no longer signs the 4.3.5 or anything in the fw 4.

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Please research (Y)
before just copying and pasting old crap

Everyone know it but he C&P this and don't read that part :p