iPhone in certain regions is locked to Apple authorized network carriers and if you’ve sign-up the iPhone with the network carrier, you can only use its sim card on your iPhone and other carrier sim cards inserted will not be able to make or receive calls and use the 3G connection. To use multiple carrier sim cards, you need to install the ultrasn0w to unlock your iPhone 3G or 3GS.
Before you can install the ultrasn0w on your iPhone 3G or 3GS 3.1.2, you need to jailbreak it first with the custom firmware to preserved its baseband being updated. If you’re on Mac PC, install pwnagetool 3.1.4 to create 3.1.2 custom firmware and if you’re on Windows PC, ask your friends who are using Mac PC to help you. Download pwnagetool 3.1.4 and 3.1.2 firmware for iPhone 3G or 3GS, follow Technobuzz.net’s guide to jailbreak iPhone 3.1.2 with Pwnagetool 3.1.4.
Once your iPhone 3G or 3GS 3.1.2 is jailbroken, install the ultrasn0w.
- On your iPhone, launch Cydia installer and update when Cydia prompted to.
- After restarted Cydia installer, go to Manage, Edit and tap Add.
- Enter http://repo666.ultrasn0w.com/ to the text field and tap Add Source.
- Once the source has been updated, press Return to Cydia and then tap Done.
- On the Sources, select repo666.ultrasn0w.com from the list of Entered by User and you’ll see ultrasn0w package there.
- Select ultrasn0w, Install and tap Confirm. Cydia installer will install the ultrasn0w.
- Once installation completed, press Return to Cydia and restart your Apple iPhone.
Once it’s completed, insert other carrier sim card and you will see the network signal bar, which means you’ve successfully unlocked your iPhone 3G or 3GS.