So i concluded that if you are reading this article, you want to unlock your Iphone to be able to use it with another network. Here is how you can do it.
Before you do that however, i need to remind you that once you connect to Itunes, it automatically checks your latest Iphone software update. It is strongly advisable to turn off the automatic update on your Itunes! Do NOT update to the latest version unless you are sure that ultrasnow is updated to cover the changes. As i mentioned in my earlier posts, it is not only about Jailbreaking (allowing installation of apps other than Itunes store ones) it is mainly about unlocking (I can really care less about apps from outside the Itunes store cause i have all what i need from there, but i want to able to use my phone with a mobile provider of my choice).
So, by updating to the last firmware for your Iphone, Apple smartly works on two components: The software version, and the modem firmware (Baseband). Although your Iphone can be still Jailbroken (Iphone software updated to version 4.1 for example) you will find out that it got locked again, and all what you will have is a fancy Ipod touch until a way is found to unlock it again.
Anyways, i learned the hard way so here is the easier way!
After installing limera1n and Cydia, you are almost set. Press Cydia to launch the application.
Select the Manage tab at the bottom of the screen
Select the Sources button
If the ultrasn0w repo is not present press the edit button at the top right of the screen.
Once the source is added, press the return to Cydia button
Press the done button at the top right of the screen.
Press to select repo666.ultrasn0w.com from the list.
Press to select the Ultrasn0w from the list of packages.
Press the install button at the top right of the screen, then press the confirm button at the top right of the screen.
After the completion of the installation, return to Cydia.
Press the home button then the power off button and slide to turn off your Iphone. Press the start button to power on again.
The Iphone may take some time to get back on but don’t worry because you already unlocked it and can use the SIM of your choice!