Hey Guys, here is pH (Pedro Henrique Franceschi). Today, I developed a tool to Downgrade your iPhone Baseband from 02.30.03 to 02.28.00 based on GeoHot’s method. The tool is called pHaseBanDowngrader and works great. You may need to downgrade your baseband to use Yellow Sn0w to unlock. As you may know, YellowSn0w only works on 2.28 baseband. Previously, those of you that upgraded to 2.2.1 could not use YellowSn0w. Now you can.

Okay, here is some simple instructions about how to use it:

1. Download the .zip in the end of the post.
2. SSH into your iPhone and put the downloaded folder (phasebandowngrader) inside the folder /Applications/.
3. In MobileTerminal.app, type “login” and enter “root” as user, the default password is “alpine”.
4. Now, type “cd /Applications/phasebandowngrader && ./phasebandowngrader”. Follow the screen instructions.
5. Enjoy!

Many guys from irc.osx86.org had tested it and they are loving the downgraded iPhone. To use that tool, you need to have an iPhone with the Bootloader 5.8. If your iPhone was manufactured before September 2008, you are 5.8. If your device is 2.2.1 OOB (Out Of Box), you can’t downgrade the Baseband because you have bootloader 5.9.

If you want to know what is your Bootloader version, check this link in TheiPhoneWiki.org. Also, read the README that is in the .zip.

Click here to Download pHaseBanDowngrader 1.0 for iPhone 3G!

Enjoy, :D !

Bye!

PS: I’ll work with BigBoss in a GUI version of this tool, but you can use this for now, :) .

1) If you are on tmobile USA you should disable 3g in settings or sbsettings.
2) YellowSn0w does not work with a SIM PIN. You  must disable your SIM card pin lock.

As I said, if YellowSn0w is not working great for you, keep checking their web site for updates.

If yellowsn0w isn’t working for you take out your sim card and look at the numbers printed on it. There are 4 horizontal rows of numbers and 1 vertical. Look at the first 2 digits of the vertical row of numbers if it starts with 36 or higher you will not be able to use yellowsn0w (yet). Dev-Team is aware of the problem and is working on fixing it.

There is also a user-generated success and failure report here.

1) You must be on 2.2 with modem firmware 2.28.00. If you are on 2.2 firmware but used pwnage you probably have baseband modem firmware 2.11.07 (from 2.1) or something earlier. This will not work. SO first step is to check your modem firmware: settings, general, about, read modem firmware. If you are on 2.28.* then you are done and can skip to step 3.

2) Restore to 2.2 in iTunes and jailbreak with quickpwn. You cannot use pwnage for this. You must restore in iTunes stock. Pwnage disabled baseband update. It will not help you.

3) After you are jailbroken repeat step #1 to verify you are on 2.28.00 modem firmware. If so, fire up Cydia and go to sources and add the dev team’s cydia source. (Note: dev team asked for no one to link the source directly. You can get the link from their post here at the bottom under “Release Info” heading).

4) Install yellow snow app and reboot your iPhone with your new sim card installed. Wait 60 seconds or so for carrier lock. If it doesn’t connect, try pulling the sim and inserting again and waiting another 60 seconds.

Note this is an unobtrusive unlock. In the past, the baseband was flashed. There is no baseband flashing for this. It should be safer as nothing is being flashed so nothing can be bricked. The unlock installs an activate daemon that runs on boot. This actively injects necessary data to keep the device unlocked. If you uninstall the unlock you should be back to where you started without any harm.

This is still in beta stages and actively being developed. If it’s not working well for you check back in Cydia every few hours and see if there is an update.

Check the dev team blog here for details, news and updates on this.

Troubleshooting:
For those that cant get this to work, and don’t want to wait for dev team to stabilize it, you can try messing with it in the command line. Reboot iPhone with no sim card inserted. Pull up mobile term and type: yellowsn0w -s and then insert the sim card. Wait a bit and it should connect.

Also make sure your SIM PIN is disabled.

Quick question and answer:
Q: Will this risk ruining my baseband?
A: No, it does not flash your baseband. It is a program that stays running on your iPhone. It is safe.

Q: Does the daemon take up a lot of CPU or drain the battery?
A: Probably not. It seems to say 0% cpu and 600kb RAM used. I would not worry about it for now.

Q: How can I update my baseband to 2.2 without restoring in iTunes
A: Right now you cannot. Maybe later someone will release something with bbupdaterextreme and a fls image but no such package is available, has been developed or tested for you.

Q: Can I use pwnage instead of quickpwn?
A: No, pwnage disables baseband update. You must restore a stock firmware image.

Q: Where do I get the firmware image?
A: If you click restore in iTunes, iTunes will automatically download the latest firmware. Or you can get it from my firmware page.

Remember this is still beta software so if it is not working well, it is likely not something you did wrong. Check for updates.