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iPhone 3G SIM unlock guide – yellowsn0w unlocks iPhone 3G for any GSM network

By: , IntoMobile
Sunday, January 11th, 2009 at 4:52 PM

Welcome to IntoMobile’s iPhone 3G unlock tutorial. In this step-by-step DIY guide, we’ll walk you through the steps needed to unlock your iPhone 3G’s GSM baseband (cellular modem) for use on any GSM network in the world.

The software-unlock solution, curiously dubbed “yellowsn0w” by the iPhone-hacking gurus on the iPhone Dev Team, is fairly straight-forward and low-risk. But, be warned, whenever you fiddle around with anything that involves the “baseband,” you’re running the real risk of turning your precious handset into little more than a paperweight – the iPhone 3G is no exception.

The yellowsn0w utility requires that you update your iPhone 3G’s baseband firmware to the newer 02.28.00 firmware version that comes bundled with the iPhone 2.2 OS. The iPhone Dev Team had previously warned against updating the baseband firmware (modem firmware), in hopes of preserving the older firmware. But, thanks to breakthroughs made by the iPhone Dev Team, yellowsn0w works with the new 02.28.00 baseband firmware. In fact, yellowsn0w will only work with the new iPhone 3G modem firmware version – so you may have to update your iPhone 3G to iPhone 2.2 OS (or do a “Restore”) using iTunes. – [Update] yellowsn0w will ONLY work with the 02.28.00 baseband, regardless of which iPhone OS you are running. Update to iPhone 2.2.1 OS through PwnageTool or you will lose any chance of using yellowsn0w. yellowsn0w has been updated to v0.9.7

For clarification:
The yellowsn0w utility isn’t an “application” per se. It is a command string that executes itself upon reboot, and it’s completely invisible to the user. You’ll never see a yellowsn0w icon or any GUI, but you’ll know it’s there when you pop in your pre-paid international SIM card and your iPhone 3G locks on to a tower.

So, with the formalities out of the way, we present to you the iPhone 3G software unlock tutorial:

  1. Ensure that your iPhone 3G is fully (or at least 80%) charged.
  2. Update your iPhone 3G to the iPhone 2.2 OS through iTunes (no Shift-Click or Option-Click required).
    • Do NOT update to iPhone 2.2 OS through PwnageTool or any other jailbreak utility.
    • If you are already running a jailbroken version of iPhone 2.2 OS, you can simply “Restore” your iPhone 3G through iTunes (no Shift-Click or Option-Click required).
    • If you are sure you already have the 02.28.00 baseband firmware installed, skip to Step 3.
    • You an check to see what modem firmware (baseband) version your iPhone 3G is running by navigating your iPhone to Settings>General>About>Modem Firmware
  3. Jailbreak your iPhone 3G using Pwnage Tool 2.2.1. (Find the tutorial here)
  4. Once your jailbroken iPhone 3G reboots, you’ll want to fire up either Cydia or Installer (both of which were automatically installed by PwnageTool (see Step 3).
    • Add “” to your Cydia “Sources” list (repository list)
    • Add “” to your Installer “Sources” list (repository list)
  5. Search for “yellowsn0w” in either Cydia or Installer.
  6. Install “yellowsn0w”
  7. Return to homescreen by pressing “Home” button
  8. Reboot iPhone 3G
    • Hold down “Power” button, then “Slide to Power Off”
  9. You should now have a fully unlocked iPhone 3G!

About The Author

Will Park

Will hails from The City of Angels - Los Angeles, California. He spends his time playing with his numerous gadgets and looking forward to seeing what future holds for mobile technology. An avid promoter of a fully "digital" life, he promotes the widespread adoption of truly mobile, paper-less living. He dreams of the day when he can go completely digital. No more snail mail, paper receipts, bound books, notepads/spiral notebooks, credit cards, hard currency. He's a digital warrior - fighting for the converged life. He is an idealist and a realist - he has a perfect view of what the world should be but knows that the world is not perfect. Can we ever hope to see Will's dream become reality? We'll see...