iPhone 3G iOS 4 Jailbreak and Carrier Unlock Guide

IMPORTANT: Due to changes in iTunes 9.2+ iOS verification model, you have to backup your “SHSH blob” first before continuing. Fortunately we have a dead-easy step-by-step guide for you guys. Once you are done, come back and continue.

Welcome to the world’s first iPhone iOS 4 Jailbreak and Carrier unlock guide. Let’s just dig right in!

NOTE: This guide is continually updated based on conversations in the comments section as well as updated software like redsn0w coming out and fixing problems for people. Please let us know in the comments if there is something else we need to update/add/clarify to make this guide easier.

This guide is ONLY for the people who meet the following criteria:

  • You have an iPhone 3G (NOT 3gS)
    • 3GS doesn’t work because you cannot jailbreak it as of yet.
      • Update #1: PwnageTool 4.01 (Mac OS X only) was released and supports jailbreaking the iPhone 3GS. For Windows users, we need to wait a bit longer. This is not a guide will not work for PwnageTool or for 3GS’s!!
    • If you have an original “2G”/EDGE-only iPhone, we have a new 3.1.2 guide for you! You can’t get iOS 4 unfortunately.
  • You are currently on OS < 4
  • You are currently on baseband 05.13.04 or less
    • Check your version by going to Settings > General > About > Modem Firmware
  • You did not use the spirit jailbreak

We will continue updating this guide as known good pwnage is released.

This how to guide is in two sections, jailbreaking and carrier unlocking. If you are an AT&T user, please stop after completing the first section – there is no “carrier unlock” for you because AT&T is the official carrier in the US. If you are a T-Mobile user please continue all the way through as you will need to “carrier unlock” your device to have it work on T-Mobile’s US network.

If you are not in the US you can replace the instructions above where “AT&T” represents the official iPhone-compatible network in your region and “T-Mobile” represents the unofficial-but-technically-compatible network in your region.

Required Items

First Download iTunes 9.2

Then download redsn0w 0.9.5b5-5

Download the iPhone IPSW (iPhone1,2_4.0_8A293m_Restore.ipsw)

Step 1: Jailbreaking

Update your iPhone to iOS4 via iTunes 9.2.

NOTE: If, by the time you are working through this guide, there are newer versions of iOS 4 available via iTunes (like 4.0.1, 4.1.0, etc.) and you are unsure if the guide will work on those newer versions (and we haven’t posted an updated guide yet), you can use this iPhone OS download utility to download the exact firmware version you want.

iOS 4.0.1 NOTE: A few readers have pointed out that you can successfully install 4.0.1 by applying the update through iTunes, but using redsn0w to jailbreak an iOS 4.0 IPSW file and flash that to your device instead during the Jailbreak step. You will still have iOS 4.0.1 on your phone, but the core jailbroken parts will be from the 4.0 IPSW file.

REMINDER: You need to have backed up your “SHSH blob” before doing this next step. We have a guide for that here (it’s a new thing with iTunes 9.2+). When done, just come back and continue.

Plug in your iPhone

Go to the iPhone within iTunes SHIFT+Click the Restore button

  • This allows you to manually select the .ipsw file you previously downloaded
  • Update the iPhone

NOTE: If you are reading this tutorial long after iOS 4 has been out and there are newer versions like iOS 4.1, please check the site for an updated guide as Apple has a habit of re-locking-down future releases of OS’s that lock basebands. So you just want to be aware of the challenges before doing it.

Open and run redsn0w.

NOTE: Make sure iTunes is no longer running at this point.

Windows Tip: Do not run redsn0w from your desktop. If you are using Windows 7, right-click on redsn0w.exe, go to Properties and set it to run in XP Compatibility Mode, and then right-click on the executable and “Run as Administrator” when launching.

  • Select the .ipsw file you previously downloaded
  • Select the desired options

Then hit Next, and following the prompts on the redsn0w screen, turn OFF your phone but leave plugged in:

Follow onscreen directions to set your phone into DFU mode:

Click “finish” and let the jailbreak complete:

That’s it! your done!

At this point if you are on AT&T (or whatever official carrier is in your area) you are all done. Your iPhone has iOS 4 on it and you are ready to get started with the new iPhone features!

If you still need to “carrier unlock” your iPhone to get it working on an alternative network, keep reading!

Step 2: Carrier Unlocking (e.g. T-Mobile)

Alright, you have your phone updated to iOS 4 and now it’s time to carrier unlock it so it works on other GSM networks, so let’s get going!

Go into Settings > General > Network and Turn off 3g:

Run Cydia (it may need to update and restart itself a couple of times, don’t rush it)

Search for the “ultrasn0w” application  <– the “0″ is a zero

NOTE: If you do not see ultrasn0w listed in Cydia directly, you may need to register the default ultrasn0w repository (http://repo666.ultrasn0w.com/). Reader ‘Gaf’ has provided instructions on how to do that down below.

Install ultrasn0w:

Now reboot the device. Insert the unsupported SIM (e.g. T-Mobile in the USA is a common one) and… Wait for it…..waaaaaiiittt for it……

There!… your good to go.

That is it, can you believe how easy that was? We just ran the ultrasn0w app and it cracked our baseband for us wide open so our iPhone can be a good citizen of other GSM networks!

Hope you enjoyed this guide! If you run into problems, please post the issue in the comments and we’ll see if we can help.

T-Mobile Cellular Data Network Settings:

Your mileage may vary, some users are reporting success, some not.


  • APN: epc.tmobile.com
  • Everything else blank


  • APN: epc.tmobile.com
  • Username:
  • Password:
  • MMSC: mms.msg.eng.t-mobile.com/mms/wapenc
  • MMS Proxy:
  • MMS Max Message Size: 307200
  • MMS UA Prof URL: http://www.apple.com/mms/uaprof.rdf

Internet Tethering:

  • APN: epc.tmobile.com

Misc MMS Problems

Reader Shah found a solution to folks having MMS/low-resolution picture problems:

Open Cydia and make sure http://www.sinfuliphonerepo.com is added to your sources
Tap on Sections > SiNfuL iPhone and install T-Mobile iOS4 MMS Fix

After installing and rebooting…
- Go into Settings -> General -> Network -> Cellular Data Network
- Make sure your settings are as follows…

Cellular Data
APN: epc.tmobile.com
(Choose the correct APN depending on what kind of account you have)

APN: epc.tmobile.com
MMS Proxy:
MMS Max Message Size: 1048576

Saving SHSH Blob

Reader BANK below points out that the iphone-dev team (the guys behind all the cracks we use for these guides; they know what they are doing) has recommended that users start saving their “SHSH blobs” for future Jailbreaks and Unlocks:

Cydia starting to save your SHSH blobs too, just like it does for iPhone3GS, ipt3G and later devices. That’s because starting with 4.0, Apple started putting a “soft” SHSH blob check in the firmware. The SHSH blob check is very real in the sense that if iTunes can’t get your blobs (because the Apple signing window has closed), the iTunes restore will error out. But it’s “soft” in the sense that those devices can always use redsn0w or PwnageTool to get past the error (the bootroms themselves for those devices don’t require blobs to be in the firmware files, unlike the newer bootroms).

Fortunately Cydia has built-in functionality to do this for you by saving out your phones SHSH blob to the Cydia’s server.

NOTE: This will cause device-identifying information to be saved to an external server. Just be aware of this before clicking the button.

iPhoneHeat has put together a guide on how to use Cydia to save your SHSH blob to the Cydia servers if you decide this is something you want to do.

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