Unlock your iPhone 3GS (04.26.08 – 06.15.00) running on iOS 5.0.1 using ultrasn0w 1.2.5

If you’ve been searching for a tutorial for unlocking your iPhone 3GS running on iOS 5.0.1 then you’re in luck, the Dev-Team have released the new version of Ultrasn0w as expected.
To unlock a phone means to remove it’s carrier restriction. Unlocking is technically reversible so you don’t have to worry about voiding your warranty too much. If your phones start acting weird you can restore it through iTunes and send it to be repaired, but only if you actually can restore it, that is, if it works to the point that it can be restored. Legally, you can unlock your phone, it is not protected under the DMCA agreement but it can void your warranty if the seller finds out. Also important to note is the fact that some carriers have no problem with unlocking, to be sure just call them and ask. Some even unlock the phones themselves for a fee.
With this 1.2.5 version you’ll be able to unlock your iOS 5 but there’s a catch, it will only work on the following basebands:
- 4.26.08
- 05.11.07
- 05.12.01
- 05.13.04
- 06.15.00 (Special iPad Baseband)
If you don’t know what a baseband is or how to check your version don’t worry about it, i’ll explain it to you. A baseband is a word that describes a range of frequencies that your phone uses in order to make and receive calls through your carrier, it’s basically your phone’s Cellular Modem.
But that is just a random fact, in our situation we just have to check the version of our Baseband which can be found in Settings – > General -> About and look for the field entitled Modem Firmware. If you have one of the above posted versions then continue scrolling down to the guide showing you how to unlock your iPhone3GS running on iOS 5.0.1.
Important! Do not upgrade your iPhone to iOS 5.0.1 using iTunes as this will update your baseband as well. You need to create a custom IPSW through RedSn0w or Sn0wBreeze. Click here for more info
Note: While this is not mandatory or required it would be good if you can sync and backup your iPhone with iTunes to make sure you’ll save all your important data (photos, music, documents, settings and contacts)
Step 1. Firstly, your phone must be Jailbroken in order to do this.
Step 2. After your iPhone has been jailbroken go ahead and launch Cydia.
Step 3. Do a search for ultrasn0w 1.2.5. If you find it there then proceed to step 6, If not then you have to add it manually. But don’t fear because this is really easy to do. Proceed to step 4.
Step 4. Just go to Manage , then Sources
Step 5. Tap on Edit and then on Add. After this write down the following URL http://repo666.ultrasn0w.com
Step 6. Install Ultrasn0w 1.2.5 by clicking install and then confirm
Step 5. Once UltraSn0w is installed you must restart your iPhone 4 and run RedSn0w to boot tethered, you’re done!