Upgrading 3GS to 4.2.1

[estranged12]

Hi all,

I currently own a jailbroken/unlocked 3GS @ iOS 4.0.1, baseband 5.13.04 and NEW bootrom (and for now I rely on my unlock to use my phone). I also have SHSHs all the way from 3.1 to 4.1.

I would like to upgrade it to 4.2.1 while preserving my unlock. I checked out the dev team blog, but it was unclear whether I should just upgrade using a stock IPSW or I should find a custom one in order to do this. Please help.

Thanks

[pratt1503]

Hi all,

I currently own a jailbroken/unlocked 3GS @ iOS 4.0.1, baseband 5.13.04 and NEW bootrom (and for now I rely on my unlock to use my phone). I also have SHSHs all the way from 3.1 to 4.1.

I would like to upgrade it to 4.2.1 while preserving my unlock. I checked out the dev team blog, but it was unclear whether I should just upgrade using a stock IPSW or I should find a custom one in order to do this. Please help.

Thanks

You need to build a CF with redsn0w and this will keep your baseband as it is, so you would have 4.2.1 with 5.13.04 baseband and there for unlock with ultrasn0w.

So you need to download the latest redsn0w
A clean 4.2.1 firmwear
and make sure you dont check the option that installs the iPad baseband.