Hi guys! There are have been a lot of requests on how to unlock iPhone's that do not have working WIFI. There have been a few other tutorials similar to this but often people find them very unclear and hard to work with. I will do my best to make this as simple as possible.
First of all, there are a few things we need to clear up. For this tutorial we will be using Ultrasn0w 1.2.5, this means it will be compatible with the following basebands: iPhone 4 01.59.00, iPhone 3G/3GS 05.11.01, 05.12.01, 05.13.04 and 06.15.00. Your iPhone will need to be jailbroken with either Pwnage Tool, or Redsn0w, this will not work with Spirit.
Here we go.
1. Prep - You will need to download the following two files.
DiskAid (ether Mac or PC) Ultrasnow 1.2.7 deb + MobileSubstrate
2. Connect iPhone to computer using USB cable
3. Open DiskAid(or your iDevice exploring software of choice)
4. Click on the folder 'Root' on the right hand side. Your screen should look the same as below.
11. Simply restart your iPhone twice and Ultrasn0w will be installed and running. (Restarting once installs Ultrasn0w, restarting a second time will start your phone with Ultrasn0w running). Insert your simcard and you will be good to go!
If you have any questions or need clarification with any of the steps, feel free to ask them below and we will answer them as soon as possible!
Source : iPhoneBlogr.com