Hey everybody,

Been trying to figure out the best way to go to unlock an iPhone 3GS.

It is currently on ios 3.1.3 and modem firmware 05.12.01

I would like to UNLOCK it to work on tmobile in the US.

I would like ios 4.0 minimum, best would be latest 4.2.

I want an UNTETHERED jailbreak.

Any suggestions. I have done a lot of googling, and it seems my situation is a little trickier then others, becuase I do have the older modem firmware (it is an older 3GS), but I want to go to the latest ios.

Would love some guidance.

Thanks In Advance.

The two details that people always forget to mention when they ask for advice on 3GS iPhone unlocking.

Old or new bootrom???
Bootrom - The iPhone Wiki

Saved SHSH? Use tiny umbrella to check (and to save your 4.2.1 SHSH as soon as possible, Apple is going to stop signing 4.2.1 soon)

Without a saved SHSH, your options are more limited.

Thanks for your reply Olethros.

According to the document, looks my 3GS has the old bootrom. xx926xxxxxx.

I do not have a saved SHSH.

What do you think my best bet is?

Many Thanks.

You MUST check the actual bootrom version (via DFU). The serial number is only a "guess". I would say that your serial number is 99% likely to be old bootrom, but you never know unless you check.

No SHSH means, you can ONLY go to iOS 4.2.1 (and hurry to save your 4.2.1 SHSH NOW, before you do anything else!!!!!. Apple may stop signing 4.2.1 SHSH as early as later today)

You don't need to restore or upgrade your phone to save a 4.2.1 SHSH, just download and run TinyUmbrella The Firmware Umbrella - TinyUmbrella , connect your iPhone to the computer and click "save SHSH"

Many thanks Olethros. I am thrilled about being able to jump to the latest ios 4.2.1.

I'll go fire-up Tiny umbrella.

Sorry for my cluelessness here. I'm a little confused. I read the FAQ for Tiny Umbrella, and that doesn't seem to do the unlock. Do I use Tiny umbrealla before or after the jailbreak?

What should I use for the jailbreak / unlock ?

Thanks for your patience!

Alright, great. I was able to get the SHSH for iPhone 3GS 4.2.1 (8C148a). Thanks so much for alerting me. I was able to do it without modifying the phone by clicking the "Save SHSH" button. Thanks for the tip.

From reading around some more, it seems that I next can jailbreak and then unlock.

I was thinking of going Limera1n for jailbreak and Ultrasn0w for unlock. Do you think those are good bets?

You must use redsn0w + original iOS 4.0, 4.0.1, 4.0.2, 4.1 or 4.2.1 ( choice is yours, my preffered is 4.0.1 and 4.1 ) and depend of this custom FW from desired version - on custom FW modem part is missing + TinyUmbrella + iTunes ... so follow the next way:
1. Check with TinyUmbrella what SHSH you have stored on Saurik server / will be nice if you have catched some from Cydia /. Close TU.
2. put 3Gs on PWned DFU mode via redsn0w. Do not open still iTunes
3. open TU and start SHSH server.
4. Shift+Restore Custom FW via iTunes ( my Favorite is 4.1 custom - highly recomended ).
5. Boot it again via redsnow if not start automaticaly .
6. Install ultrasn0w via Cydia

Many Thanks debeliamark....I downloaded the 4.2.1 FW from apple. Can I use that? I don't know where to get the custom FW you write about.

I got SHSH for 4.2.1. There was also one for 4.3b (I think, I'm not in front of that computer right now) and a couple others. I clicked the button for "Get SHSH", and it got all the ones it could for the 3GS.

Thanks for your step-by-step instructions.

The instructions from debeliamark aren't correct. I would advise you NOT trust someone who has only 1 post on a forum.

As of right now, you don't need to do anything more in TinyUmbrella than you have already done.
It was very important that you have protected yourself for when Apple stops signing 4.2.1 (which could be as soon as a few hours from now)

Limera1n won't work for you, that jailbreak is only for iOS 4.1 and you don't seem to have a 4.1 SHSH.
What you need to do from here is to make a special 4.2.1 custom IPSW

Custom IPSW is made with a Mac OS X only tool called PwnageTool - there are no other reliable ways to make custom IPSW. If you only have windows (XP, Vista, 7 etc) then you simply need to get access to Mac.

My advice is to wait for the upcoming release of Pwnagetool 4.2 - which will make the process a LOT easier for you.
PwnageTool 4.2 is pretty much ready to be released, but the timing of when it is released is more political than technical. I would guess - within a week, maybe even within a day.

Hi Olethros, Appreciate your response and wise advice. I do have a Mac as well, so I will do some searching about creating the custom IPSW with PwnageTool. I'll just research this for now, and hopefully PwnageTool 4.2 will be out sooner rather than later!

Cheers, and Many Thanks!

EDIT: I just realized I did use Tiny Umbrella on my Win machine. I am not sure if this matters when it comes to using PwnageTool on the Mac...maybe I can create the custom IPSW on the Mac, then move it over and do the final steps with iTunes on Win (where I usually sync the phone).

Reference:
http://www.gadgetsdna.com/how-to-jai...nagetool/8685/