I am very confused by the usually great iClarified tutorial on unlocking 4.2.1 with redsnow.
I have a 3G jailbroken and unlocked on 4.0.1. I only have windows available so can't easily make a custom ipsw.
I want to go to 4.2.1, BUT reading the tutorial suggesting a shift restore to 4.2.1 makes me believe that I will inadvertently upgrade baseband currently 05.13.04. If that is the case then I would have to go the iPad route to unlock, which I do not want.
Have I understood correctly or will redsnow preserve baseband at 05.13.04 because it doesn't seem obvious to me.
If I am being obtuse apologies but any help in giving me comfort that I can follow tutorial safely would be appreciated.

3G jb/unlocked 4.0.1
Windows vista

Originally Posted by GranpaD

I have a 3G jailbroken and unlocked on 4.0.1. I only have windows available so can't easily make a custom ipsw.
I want to go to 4.2.1, BUT reading the tutorial suggesting a shift restore to 4.2.1 makes me believe that I will inadvertently upgrade baseband currently 05.13.04. If that is the case then I would have to go the iPad route to unlock, which I do not want.
Have I understood correctly or will redsnow preserve baseband at 05.13.04 because it doesn't seem obvious to me.

You are correct, the iClarified procedure will update your baseband to 5.15.04 - do not follow this procedure if you want to keep your baseband at 05.13.04

Custom IPSW is your ONLY way to prevent baseband update.

However just because you have windows doesn't mean you can't make a custom IPSW.

You have a few options, not all easy.

1. Find a friend with a mac, get them to make the custom IPSW and send it to you (or better yet make it yourself if your friend lives nearby)
2. Set up OS X in a virtual machine (virtualbox is free from Oracle). Then run pwnagetool in that virtualised install of OS X- the other half of hackint0sh is dedicated to explaining how to do things like this
3. use xpwn and the 3G bundle from pwnagetool 4.1.3 to manually make a custom IPSW. Xpwn is cross platform, command line and open source.

Don't rely on sn0wbreeze, for all currently released versions - it does not produce the same result as pwnagetool does. This is why we don't recommend it.

Thank you for confirming that. Will add a comment to iClarified to help clarify the consequences.

Hey there, not sure where to post this but my problem is similar and I have a few questions..

I have an iPhone 3GS on iOS 4.0.1 and Baseband 05.13.04 and I unlocked it using ultrasnow and had jailbroken it using jailbreakme. Now I would like to upgrade it to iOS 4.2.1 but without upgrading my Firmware to 06.xx.xx is it possible? And would I be able to jailbreak it, as I need to unlock it?? I'm using Windows 7.. Also, if I upgrade and jailbreak it and eventually unlock it, will I have to connect it to the computer everytime I want to boot up my phone???

Sorry for the trouble.. Thank you for your assistance.. :-)

Originally Posted by marioff21

I have an iPhone 3GS on iOS 4.0.1 and Baseband 05.13.04 and I unlocked it using ultrasnow and had jailbroken it using jailbreakme. Now I would like to upgrade it to iOS 4.2.1 but without upgrading my Firmware to 06.xx.xx is it possible? And would I be able to jailbreak it, as I need to unlock it?? I'm using Windows 7.. Also, if I upgrade and jailbreak it and eventually unlock it, will I have to connect it to the computer everytime I want to boot up my phone?

You haven't mentioned if you are new or old bootrom 3GS or if you have a 4.1 or 4.2b3 SHSH saved.

We don't yet recommend 4.2.1 jailbroken for those who have new bootrom 3GS.

See http://theiphonewiki.com/wiki/index.php?title=Bootrom for details on how to use dfu mode to identify bootrom.

TinyUmbrella can help you find out what SHSH you have saved. If you haven't already started saving SHSH and you want to remain unlocked/jailbroken then you are playing Russian roulette - if your iPhone stops booting and you have no saved SHSH then you risk being forced to update baseband and losing untethered jailbreak.

I have an iPhone 3GS, FW 4.0, BB 5.13.04, Old Boot Rom. The phone is already JB and unlocked. I'm on T-Mobile. I want to upgrade to FW 4.2.1 while keeping BB 5.13.04. Can I upgrade? What is my best option to upgrade and stay unlocked or upgrade and unlock again? Thank You! BTW I use MacOS X Lion.

I should also mention that I tried to upgrade using pwnage to make a custom FW 4.2.1 IPSW but iTunes told me that the FW was not compatible with my iPhone.