Here is a new write of the same procedure easyer for non tech folks to follow.

Upgrading to 1.1.2 in baby steps


This guide represents a joint effort by a great hacker (W9cae) and good writer who can only manage computer stuff in baby steps (me). W9cae confirms that it is technically accurate, and I confirm that it can be followed by people who are mystified by the world of unix, ssh, etc. etc. I'm one of those people, and I have followed this guide and I now have a successfully upgraded and unlocked 1.1.2 iPhone.

As always, though, you try this at your own risk. So here goes:

What you need
• An iPhone on 1.1.1 unlocked and jailbroken
• A WiFi Connection for the iPhone
• A Computer with web browser and iTunes connected to internet
• About an hour of spare time, much of which will be spent watching, drinking, and praying while things download and install.
• This guide

1. Before you begin
1.1 Sync your iphone so you don’t loose anything
1.2 If you want to play it extra safe, you could use Installer to uninstall any third party applications, and erase all content and settings (Settings > General > Reset), and then reboot the phone. If you have erased everything, you will need to reenter to your WiFi password.
1.3 Open the web browser on your computer and go to http://conceitedsoftware.com/iphone/site/112jb.html Download the 1.1.2 jailbreak to your computer. It will download as a .zip file. Open the file and it will create a folder called “1.1.2-jailbreak”. There is a README inside that folder, but you can ignore it because anything you need to know from it is already included in this guide.

2. Preparation
2.1 On your iPhone, tap on installer (and wait for sources to refresh if necessary)
2.2 From “Tweaks (1.1.1)” find “OktoPrep”. If you can’t find these, you need to first install “Community Sources”.
2.3 Install “OktoPrep”. It will run itself and then tell you that you are ready to update.

3. Upgrade
3.1 Connect iPhone to computer and open iTunes
3.2 Click on “Update” to install FW 1.1.2 (make sure you choose “update” not “restore”)
3.3 Wait the half hour or whatever it takes to complete the download and installation. A drink and a prayer help pass the time at this point.
3.4 You now have a locked and unactivated 1.1.2 iPhone.
3.5 Close iTunes, but leave your iPhone connected to your Mac.

4. Jailbreak
4.1 On your computer, open the “1.1.2-jailbreak” folder.
4.2 If you are on an OSX Mac, double click on the “jailbreak.jar” file. If you are using Windows, double click on windows.bat.
4.3 Follow the on-screen prompts as follows:
4.4 In the first window, click on the “Jailbreak” button. No need to check the “Install SSH” box unless you want it. If you don’t know what it is, then you won’t be needing it! Another stiff drink and a prayer will go down well while watching the progress bar - about 5 minutes.
4.4 At the end of this, the iPhone will shutdown and reboot itself several times. It will look like it’s stuck in a loop, but just wait it out. It will sort itself out.
4.5 Once this is finished, you can disconnect the iPhone from the computer, because the rest is done on the iPhone through its WiFi connection.

5. Unlock
5.1 Go to Settings > General > Auto Lock, and set to “Never”.
5.2 Go to Installer, and install BSD Sybsystem if it is not already on your phone.
5.3 Go to Installer, and add a new source called http://rep.frenchiphone.com
5.4 Refresh sources, and then install Anysim 1.21u, but don’t run it yet!
5.5 Reboot the iPhone
5.6 Go to Settings and turn on the AIRPLANE mode (this is very important. If you forget it your phone will get stuck in a loop and you’ll have to go and beg W9cae for instructions on how to get it out.)
5.7 Return to the Springboard and tap on the AnySIM to run anySIM 1.21u.
5.8 Your phone is now unlocked, but you are not yet finished.
5.9 Go to Installer > Uninstall, and uninstall AnySIM 1.21u.

6. Install iWorld
6.1 Turn Airplane mode off again.
6.2 Go to installer and from “Tweaks (1.1.2)” install iWorld
6.3 Return to the Springboard, tap on the iWorld icon and follow the prompts.

7. You’re done... but...
7.1 ... you’ll want to dock and sync you iphone, it should restore from backup your settings.
7.2 ... you’ll want to verify that everything is working, calls, SMSs, emails, YouTube.
7.3 ... you’ll want to check that your EDGE settings remain. If they don’t, download the EDGE settings fix from installer (Unlocking Tools).
7.4 ... if you took the safe option of uninstalling any third party applications, you’ll want to reinstall them now.
7.5 ... you’ll want to program your voicemail button. Open the phone dial pad and tap the following code: *5005*86*xxx# where xxx is your phone company’s voicemail number. Then tap call and after a second, the code will have been set.

I had a friend using AT&T. original using 1.02, then he updated to 1.1.1 and now updated to 1.1.2. He was never unlocked the phone before.

I've just downgraded to 1.1.1 with baseband of 4.02. I tried to install BB Downgrader 1.1.2 from http://i.unlock.no to change the baseband back to 4.01 but it gave me an error message.

Does anyone could help me out with this? maybe we could use BB Downgrader 1.1.2 to unlock the OOB 1.1.2. I haven't tried it yet.

Thanks.

Thank you, it work for me!

Just wondering if anyone can explain exactly what Oktoprep does? I discovered from some other posts that under the covers it simply issues the folliwng command: mknod ~/Media/disk c 14 1

In fact, you can do this manually if you just copy the mknod binary to /sys/bin, but I just don't understand the logic.

P.S. If I don't have anything to save, ie. I backed everything up in itunes and I don't really care about any installed apps because I can easily re-install them, do I still need to run oktoprep?...and if not, can I do a 1.1.2 restore instead of update?

Thanks for any insight

Hi,
I have the brand new one from US with ori. 1.1.2, now I downgraded to 1.1.1, upgraded to 1.1.2, follow your instructiuons but anySim fails everytime!
Idea?

I am frustrated!

Oktoprep is required for unlock procedure to work. It has nothing to do with your settings or restoration of your apps, music, etc.

OTB 1.1.2 cannot be unlocked because of new bootloader. This has been posted numerous times already. Please read stickies and all applicable threads before posting. Thank you.

It's amazing how so many repeat the same mistake day after day. I wonder how many brand new phones are damaged in this way?

__________________
3G iPhone 8GB

Yes, I know that much...I was just trying to get some explanation as to what oktoprep does...maybe a slightly more technical answer than, 'is required for unlock procedure'. Thanks for you effort anyway!

OktoPrep is a file that one puts on there unlocked FW 1.1.1 iPhone. It is not changed or modified due to its permissions on UPGRADE to FW 1.1.2. Now that your on FW 1.1.2 this file OktoPrep is used to break into the iPhone in a similar way the safari hole was used. So without OktoPrep your not abe to activate & jailbreak your FW 1.1.2 phone old or new bootloader. If you do a restore the OktoPrep file is wiped out and you have to go back to FW 1.1.1 jailbrake etc and start the process except for sim unlock.

I hope that has cleared up your question.

New bootloader phones are not able to unlocked just activated.