This post was published 3 months 4 days ago which may make its actuality or expire date not be valid anymore. This site is not responsible for any misunderstanding.

Before we get to the good stuff I should warn you that hacking your iPhone WILL void your warranty and following these instructions could very well get you a higher than normal bill from AT&T or whoever your carrier is that does not support iPhone tethering officially.  You could potentially screw up your phone and if you follow these steps, iPhone MVP and myself are NOT liable for anything you screw up.

This tutorial is for those of you who ARE currently jailbroken. I’m going to assume you have Cydia already installed an running for this tutorial as any good jailbreaker should. I will have a different tutorial for stock iPhones right here. Everything you need is just past the break!

1. First, we need to open up Cydia.
2. Next, tap on Manage and you should see the following:
   
3. Now we need to tap on Sources and you should see this (or something similar depending on your installed sources):
   
4. Now we’re going to tap on edit, then hit the Add button.
   
5. In the popup, type in blackra1n.com and hit Add Source.
   
6. Cydia will do its thing and add the blackra1n source to your phone and download a list of available packages to install.  Once this is done tap on Return to Cydia and then Changes down at the bottom and you should be presented with 1 new package to install:
   
7. Go ahead and install it.  Instead of forcing you to reboot or respring your device, the CommCenter (phone) process will be killed and restarted automatically so there is no waiting involved.
   
8. Now go ahead an exit out of Cydia and open up Mobile Safari.  Direct your browser to tr.im/312tether.  This is a shortened URL I created which will redirect you to the hacked carrier profile which will enable tethering.
   
9. Go ahead and tap on Install then confirm that you want to install this unsigned profile.  Once that is done, hold down the home and power buttons to reboot your iPhone.  This will take a bit longer than normal so don’t freak out, everything is fine.
   
10. Once your iPhone reboots, go ahead and go to Settings > General > Network > Internet Tethering and flip the switch to On.  Once you do that, go ahead and follow the directions on the screen and you’ll be all set to go!
    
11. Congratulations! You have successfully enabled tethering on your iPhone 3G/3GS!  Just remember, be careful how much you use this because I’m not responsible for your AT&T bill if you get charged for pay per use tethering.