How to Downgrade iOS 6 iPhone 4S Baseband 3.0.04, iPhone 4 Baseband 4.12.02 Or iPhone 3GS Baseband 5.16.07

Apple iOS 6.0 firmware which was released earlier yesterday also brought some new baseband for iDevices. iOS 6 brings new baseband 3.0.04 for iPhone 4S, baseband 4.12.02 iPhone 4 and iPhone 3GS Baseband 5.16.07.

Many iPhone users who rely on unlock may have stuck on these baseband by upgrading iOS firmware to iOS 6.0. Now the question is that is there any possibilities to downgrade your iPhone iOS 6.0 baseband to other unlockable baseband. See detailed answer after the break.

iPhone 3GS Baseband 5.16.07

If you have a 3GS (made before week 28 of 2011), it’s possible, but it involves some steps which I will write-up soon.
If you have an iPhone 4, it’s not possible, unless if the iOS is still being signed by Apple. For instance, if you have already installed iOS 6 on iPhone 4 that has baseband 4.12.02, you can downgrade to iOS 5.1.1 which has baseband 4.12.01, for as long as iOS 5.1.1 is still being signed by Apple. Apple will close the signing window within 24-48 hours after a new iOS is released so probably this won’t work for you anymore. You can never downgrade the baseband to 4.10.01 or lower even if you have the SHSH. Chip replacement is the only possibility if yours can’t be factory unlocked.
If you have an iPhone 4S, no, Apple pretty much blocked any method of downgrading the baseband or iOS for iPhone 4S.
iPhone 5? Zero possibility of downgrading of any sort (more details soon…)

UPDATE :How To Downgrade From iOS 6.0 To iOS 5.1.1 On iPhone, iPad, iPod touch

via beijingiphonerepair

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2 thoughts on “How to Downgrade iOS 6 iPhone 4S Baseband 3.0.04, iPhone 4 Baseband 4.12.02 Or iPhone 3GS Baseband 5.16.07

  1. My iPhone 3gs with early serial number and late ROM was unlocked, jailbroken and working fine until it updated to io6 by itunes which resulted in an error that I forgot but the phone was searching for a network and failed to activate by itunes or wi-fi.
    Currently the installed firmware version is: 6.0gm
    and the baseband version is: 06.15.00-6.4_M3S2

    itunes error recommended I revert to the the backup which I tried and now I have an itunes error : there is no SIM card in the installed in the ipone you are attempting to activate.

    there is no SHSH backup

    following instructions to downgrade form 6.15 to 5.15 with redsn)w o9,0.1b2 I selected the current iPhone2,1_6.0_10A403_Restore.ipsw from my Mac iTunes files but redsnOw does not support it.

    I had downloaded a number of different 5.1 ipsw files to downgrade to with the intent of unlocking but can’t get that far.

    Apsinthe did not support the attached device.

    Is my io6 baseband different than the 6.15 Ipad file?

    Am I using redsn0w correctly by targeting the currently installed 6.15 file?

    Can I downgrade to 4.0 then up to the iPad 6.15 then down to an unlock able 5.1?

    Is this phone now junk?

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