Where to start? Upgrading jailbroken 3gs on 3.1.3 to 4.2

[eagle2k]

Hello all,
I've been reading through some of the stickied threads but after having read a number of walk through, I'm still not 100% sure what set of instructions I need to follow. I have an iPhone 3GS with OS 3.1.3. My baseband is 05.12.01. The phone is currently jailbroken (which I did a while ago, so I don't remember what program I used to do so). I'd like to upgrade to OS 4.2 and jailbreak the phone. I don't have to have a carrier unlock as I have AT&T service, but I wouldn't mind having the option available it's feasible. I also only have a Windows PC. Any guidance on how to proceed/which part of the "General Info" thread to follow would be appreciated!

Thanks!!

[iYeow]

If you have the new bootrom, you are better off with IOS 4.1 ( with saved shsh blob) to get untethered jailbreak.
You can see your shsh blob on the front page of Cydia.
You restore to stock 4.1 fw by running Tss Server from the feature of Tiny Umbrella with already saved 4.1 shsh blob and then run itunes : Shift + restore to 4.1 fw. Jailbreak it with Limera1n or GreenPoison.

This method doesn't preserve baseband for unlock.
Remember to update your itunes too , the latest is fine.

[Mes]

Good thinking .... retain the baseband for a future unlock. Easy to do.

To keep the current baseband a custom firmware built with PwnageTool (Mac) is required. No problem, x98car (PM) has links & redsnow (PC) can set-it up (Special DFU mode) for iTunes to shift/select CF/restore.

There is one issue with 4.2.1 & 3GS. New bootroms (most) will be tethered. An untethered version is almost ready. Likely just a few days away.

[eagle2k]

Just checked and it shows my bootrom version as 359.3, which I believe is the old bootrom.

[Mes]

Note: 4.2.1 is currently being signed by Apple so no SHSH worries. But to get untethered, a lower version is needed (at the moment).

Just checked and it shows my bootrom version as 359.3, which I believe is the old bootrom.

I'm not really sure, but if true the jb will be untethered. x98car is sending links to custom firmwares and trustworthy. 4.2.1 plus an old baseband is good stuff

[Simon]

Sent. Restore to that, then use redsnow to install cydia.