FaceTime feature gives users the possibility to make  voice calls. Apple restricted this feature to Wi-Fi only. Today it became possible to use it over 3G!

Setup Instructions:

1. Jailbreak your iPhone 4 via www.jailbreakme.com ^[1].
2. Download and upgrade to the latest Cydia package.
3. Open Cydia, Go to Manage then Sources.
4. Click Sources, Edit then add: http://apt.modmyi.com
5. Search for "My3G" -- download, and install it. It costs $2.79. My3G makes Apps believe that they are on WiFi instead of 3G.
6. Go through the Rock setup process with a username and password. Open My3G and leave all settings on the default.
7. FaceTime should now work over 3G! -- Make sure to "Forget" the WiFi network you are on (via iOS settings) if you want to test it.

We haven't seen any difference between the 3G FaceTime call and a WiFi FaceTime call. The quality is very good.

Here's a video demo: