Well now that your iPhone 4 is jailbroken, you can now have the possibility to make Facetime calls over a 3G network. Apple only allows it over Wi-fi because of the massive strain it would put on AT&T’s network if it used 3G. But thanks to this little tweak, you make make Facetime calls from almost everywhere.
Thanks to 9to5 Mac, here’s how:
“1) Jailbreak your iPhone 4 via www.jailbreakme.com.
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.
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.”