Inside, you’ll find a brief tutorial that shows you how to verify if you qualify for an unlock, and how to go about unlocking your iPhone with UltraSn0w 1.2.5…
Step 1: Make sure you have a qualifying baseband.
To check this go to Settings > General > About and check the “Modem Firmware” section at the bottom of the page. If you are on an iPhone 4 and the Modem Firmware says 01.59.00, you can unlock. If you are on an iPhone 3GS and your firmware is any of the following: 04.26.08, 05.11.07, 05.12.01, 05.13.04, or 06.15.00 you can unlock.
If your baseband doesn’t meet the above requirements, stop here. You are not eligible for unlock. iPhone 4S is currently not unlockable.
Step 2: If you haven’t already, upgrade to iOS 5.0.1 and preserve your baseband when doing so.
Step 3: Jailbreak your iPhone 5.0.1.
Step 4: Go to Cydia and search for “UltraSn0w”. Install UltraSn0w 1.2.5.
Step 5: Remove your old SIM card and replace with new SIM card e.g. a T-Mobile SIM. You may need to cut your SIM to fit the micro-SIM slot. See the video for more details.
Step 6: Give your iPhone a few seconds, and it should now be on the new network, courtesy of the UltraSn0w 1.2.5 iOS 5.0.1 unlock.
Unless you got an iPhone 4 at launch and you were very careful to preserve it all of this time, it’s fairly unlikely that your baseband still qualifies. I know mine doesn’t.
Are you eligible for an unlock? Have you unlocked your iOS 5.0.1 installation as of yet? Let us know.