Browsing through the webpage CH28 posted I found this, it's basically saying I just need to update my baseband to be able to unlock it. So how do I update my baseband from 3.10 to 6.15 ?? I'm a little confused by the numbers now, you're saying that the 3.xx baseband is newer than the 6.xx ??
http://iclarified.com/entry/index.php?enid=4253
"These are instructions on how to unlock the iPhone 4, iPhone 3GS, and iPhone 3G for use with any GSM cellphone carrier using UltraSn0w. This will work with the iOS 4.2.1 firmware if you are on the 06.15.00 baseband.
Before you can follow these instructions you must have a jailbroken iPhone and you must be on the 04.26.08, 05.11.07, 05.12.01, 05.13.04, 06.15.00, or 01.59 baseband(modem firmware)"