Some iOS users still do not know the difference between unlocking and jailbreaking, I want to make this clear before I go any further. So, jailbreaking means to installed unsigned codes on your software in order to change various things. On the other hand, unlocking an iOS device means to give it the ability to use any SIM card on it despite the request of the carrier. So, since all these things are clear, now we can get back to business. When jailbreak is performed, some devices might lose their unlocking status and users need to redo the whole action all over again. In this respect, developer work pretty hard to make our devices accessible and easier. Recently, a new jailbreak utility was released, namely UltraSnow Fixer which preserves the baseband for iPhone 4 and iPhone 3GS. In the same time, it supports the following basebands: 01.59.00, 04.26.08, 05.11.07, 05.13.01, 05.12.01 and 06.15.00. For those of you who already upgraded to iOS 6, this is great news.
In order to use the UltraSnow Fixer to preserve the baseband of your A4 device running on iOS 6, you need to perform jailbreak iOS 6 first. Until now, only tethered jailbreak is available. Therefore, here is how you unlock iOS 6 on iPhone 4/3GS using the UltraSnow Fixer.
Step 1: The first thing you need to do is to jailbreak your currently upgrade iOS 6 on iPhone 4 and iPhone 3GS. Since there are many jailbreak tools available, this thing should not be that complicated.
Step 2: Launch Cydia and open the Sources tab. You need to add a specific source in order to find the specific program. This is the source http://repo.iparelhos.com.
Step 3: You need to install the official UltraSnow version before you install UltraSnow Fixer.
Step 4: After UltraSnow was installed, you can search through Cydia to download and install the UltraSnow Fixer.
This is all. You do not need to do anything else. The program will do its job and you can enjoy a brand new unlocked device.