Possible Upgrading

[mcinsane]

My iPhone is currently at v3.1.2 and I want to upgrade to the new OS4, but I want to stay jailbroken. Is there anyway to stay jailbroken and upgrade Or am I stuck at 3.1.2?
I am a MC model also, which is why I'm at 3.1.2.

[i.Annie]

Which iPhone is this?

[mcinsane]

3gs

[i.Annie]

SHSHs determine whether you can upgrade or not. If you have saved SHSHs before and have 4.1, it's possible for you to go to 4.1 and maintain baseband to keep the unlock. You also need to figure out the bootrom version of your device, whether it is old or new. Old boot devices can simply go up to 4.2.1 via custom firmware and be untethered.

If you're having trouble following, you should answer a couple question first so that the best route can be determined for you.

1) Is it a new or old boot device
2) Do you need to unlock
3) Do you have any SHSHs saved
4) What machine are you running

Find out your bootrom by following this guide:

How to Check iPhone 3GS New Bootrom / Old Bootrom (iBoot) Version | Redmond Pie

359.3 is old and 359.32 is new

Find out if you have SHSHs by going to thefirmwareumbrella.blogspot.com and downloading TinyUmbrella. Click "Save SHSH" and see what the log below tells you.

[mcinsane]

1) old bootrom
2) no
3) SHSHs saved
4) Win 7

[i.Annie]

Old boot and no unlock, my dream come true My favorite lol.

Hit upgrade in iTunes, it'll take you to 4.2.1.

Download Redsn0w 0.9.6b6 and a stock 4.2.1 firmware. When the restore has finished, run Redsn0w and browse to the 4.2.1 ipsw you downloaded. Select Cydia and if you want multitasking and wallpaper, select those too. If you don't want them, don't select them. Then just follow the on-screen instructions.

Be sure after you restore to activate your phone first before jailbreaking because you want to avoid hacktivating. So plug it into iTunes after you restore and let it activate, then run Redsn0w.

[mcinsane]

Thank you! Its jailbroken now :-P

Now to my knowledge it cant be done, but i wanted to ask.

My brother just got a new iphone, 3GS, which probably means that its a new bootrom, no SHSHs saved. Its activated and unlocked though. Is it possible to jailbreak his phone? or no.

[i.Annie]

When you say "unlocked" do you mean he is using another carrier besides the official one for the phone/or that it is factory unlocked?

You can likely jb it, it's just whether it's tethered or not. Check the firmware version.

[mcinsane]

hes with the official carrier.

He has firmware 4.2.1

[i.Annie]

If it's a brand new 3GS then it's got the new boot which means it is gonna be tethered jb on 4.2.1.

If he would like to proceed with jb, redsn0w 0.9.6rc8 will do it.

[mcinsane]

what do you mean exactly by "tethered jb on 4.2.1."

[i.Annie]

it means whenever your device shuts off or reboots you have to use Redsn0w to boot tethered so that it will boot up again.

[StealthBravo]

So do not let your battery die or restart your device unless you have your computer near by