Apple recentrly released new version of iPhone OS 4. it is called iOS 4.0 GM. Here is an update from DevTeam about iOS 4 jailbreak:
For those who can legitimately activate to the iPhone3G 4.0GM seed, the “point to previous IPSW” redsn0w trick works and will jailbreak your 4.0GM. The “trick” is to point redsn0w at the 4.0beta4 IPSW instead of 4.0GM (do this after you've updated to 4.0GM and activated through the new iTunes 9.2 on your Mac). Since the carrier unlocks aren't yet supported at 4.0, don't do this if you use yellowsn0w/ultrasn0w/blacksn0w. Many JB apps are still pretty buggy in 4.0, so again this is mostly useful only for developers of those JB apps.
Note: If you're experiencing MobileSafari crashes, double check that you're running the version at the bottom of this page.
For those without legit iPhone3G 4.0GM seed access, please wait until the full public 4.0 release for updates to the jailbreak tools.
Last week Apple has released its iPhone Os 4.0 beta 4 and redsn0w is finally updated to support this as well as beta 1. New version of jailbreak is 0.9.5.b4 and it can be applied on iPhone 3G only(!).
Redsn0w 0.9.5.b4 is targeted at developers who make jailbroken apps, and will not work if you are already using blacksn0w, ultrasn0w or yellowsn0w.
iPhone Dev-Team warns:
"You should stay clear of this beta software if you rely on a carrier unlock."
To use the jailbreak, follow the guide below:
Download redsn0w 0.9.5.b4 here. (Only Mac OS X version since app are developed on this OS).
Make sure you have already activated your iPhone 3G with iTunes and your own developer ID.
Launch the jailbreak.
Select your stock iPhone1,2_4.0_8A274b_Restore.ipsw (beta4) or iPhone1,2_4.0_8A230m_Restore.ipsw (beta1) file that you used to update your firmware.
Choose "Install Cydia" and then click "Next". Use DFU mode to install the redsn0w.
When your iPhone 3G comes back up, you will notice Cydia has a blank white icon. It also has no sources so you should go to the Sources panel and add this repo: http://apt.saurik.com/cydia-3.7 (make sure you are connected to the Internet before). When Cydia restarts, you should see its real logo now, and the standard sources should be ready to use.
Sherif Hashim has discovered an exploit which may allow unlock of the latest iPhone OS 3.1.3 baseband 05.12.01. Such unlock utilities for previous baseband versions were called blacksn0w, ultrasn0w и and yellowsn0w. MuscleNerd, the member of DevTeam, has already confirmed it is working. So the timing of the unlcok release is totally up to them right now.
Here is an official update from DevTeam:
"We’ve started to look at his crash but it’s a long road between any given crash and a fully working unlock, and we couldn’t put an ETA on it even if we wanted to. It’s not even guaranteed that an working unlock will come from this particular crash — it’s just too early to tell."
RedSn0w is an easy to use, multi-platform, multi-device jailbreaking and unlocking (iPhone 2G only) tool from DevTeam. It supports firmware 3.0 and iPhone 2G (original iPhone), the iPhone 3G (but not the 3GS) and also the iPod touch (first and second generation):
DevTeam released PwnageTool for firmware 3.0. Here is the list of supported deviced:
iPhone 2G - jailbreak and unlock
iPhone 3G - only jailbreak, use only with official unlocked iPhones
iPod Touch - jailbreak
iPod Touch 2G - not supported, use redsn0w
iPod Touch 3GS - not supported
If you are using a 3G iPhone with yellowsn0w and rely on yellowsn0w to obtain cellular service, then you should NOT use PwnageTool right now. Ultrasn0w is not included with this release and therefore your baseband will be locked and unable to use an operator other than the official one it was bought for. Ultrasn0w will be release via APT (cydia and icy) soon (update: Ultrasn0w released). If you have an original iPhone (1st generation) then 3.0 unlock works with this PwnageTool release.
Yellowsn0w in its current form will NOT work with the baseband version that is present in the 3.0 update, you will need Ultrasn0w, which will be released sometime soon, Ultrasn0w will work with all iPhone 3G models (but not 3GS), even ones that were previously unlockable, Ultrasn0w will be released via APT (this means you can get it via Cydia or Icy).
PwnageTool will NOT work for the iPhone 3GS. PwnageTool WILL work for Original iPhone (1st Generation), Original iPod touch (1st Generation) and the iPhone 3G.
WARNING: This tool is NOT a toy. Just use it if you can’t use yellowsn0w on your 2.2.1 iPhone 3G. Otherwise, DO NOT INSTALL IT JUST TO TEST! YOU HAVE BEEN WARNED!
This software is for iPhone 3G users who upgraged to 2.2.1 firmware, but still need yellowsnow unlock. Yellowsnow doesn't work with 2.2.1 firmware's 02.30.03 baseband. So we need to downgrade it to version 02.28.00, that was used in 2.2 firmware. To downgrade it you need this software, that you can install via Cydia. It is very easy to use. Just download it from Cydia (called 3G BaseBand Downgrage), open the app and click Go.
The 3G Baseband Downgrade just works on iPhones 3G with Bootloader 5.8, that can be detected using minicom. If you don’t know how to use minicom, there’s a “simple” way to know if you are 5.8 or 5.9 (but this is not 100% sure). If your iPhone was manufactured before September (2008), you are 5.8. Otherwise, you are 5.9 (that can’t be downgraded).
iPhone 3.0 OS is jailbreakable on all devices. It’s just those using 3G yellowsn0w that have to show some restraint and wait for PwnageTool to create a custom IPSW that avoids the baseband update. If you are using yellowsn0w, do not update or restore to iPhone 3.0 firmware. You will lose yellowsn0w and find yourself unable to revert the baseband to get it back.
DevTeam updated yellowsn0w to version 0.9.8. It will not work with regular 2.2.1 firmware. If you want 2.2.1, you need modified (!!!) firmware 2.2.1, in which old baseband from firmware 2.2 is preserved.
Version 0.9.8 adds strability and fixes some bugs. So If everything works fine, I reccomend just leave it like it is. For example, I use 0.9.6 and feel happy with 2.2 firmware.
Yes, DevTeam released new version of their software. First of all, please, do NOT use unofficial software from unknows sites (f.e. quickpwm.com). We recommend to download from torrent or official mirors.
We regulary publish latets software and firmware links. Use them or the same ones from DevTeam site.
iPhone 3G + NO UNLOCK: If you do not need unlock, you are using your iPhone with one carrier or you hae factory unlcoked iPhone, just restore or upgrade to 2.2.1 using iTunes and use QuickPwn to jailbreak and add Cydia and Installer.
iPhone 3G + UNLOCK: you need to preserve current baseband software. Preserving the baseband will ensure that you can still use “yellowsn0w” the iPhone 3G unlock application. To upgrade your phone to 2.2.1 and preserve the state of the baseband you need to create a custom .ipsw with PwnageTool. This custom .ipsw will not contain the baseband update but of course will still allow all the cool new stuff from 2.2.1. PwnageTool is only available for Mac OS X.
DevTeam updated yellowsn0w to version 0.9.7 to work with modified (!!!) firmware 2.2.1, in which you preserve old baseband from firmware 2.2.
Apple has just pushed out Firmware 2.2.1 for iPhone and iPhone 3G, iPod touch, iPod touch 2G. You can download them here. Firmware 2.2.1 cannot be jailbroken at this time, so unofficial application users should wait for new version of QuickPwn from DevTeam. Unlock (yellowsn0w) also doesn't work for 2.2.1.
This update contains bug fixes and improvements:
Version 2.2.1 (Build 5H11)
Modem Firmware 02.30.03
Improved general stability of Safari
Fixed issue where some images saved from Mail do not display correctly in the Camera Roll
Fixed issue that caused some Apple Lossless (ALAC) to skip during playback
Unofficially Apple fixed SMS bug: users suddenly experience inability to send SMS text messages on the iPhone 3G, receiving the message "error sending" upon attempting to send.
Dev Team finally made it. They created software called yellowsn0w, that unlocked iPhone 3G. Now you can use any carrier you want. I successfully unlocked my US version.It works much more stable than sim proxy method.
Please, back up everything on your iPhone before you start, just in case. Everything you do is your responsibility. I had to go through all 4 steps to make my iPhone 3G work. I used only my new sim without sim proxy.