VoIPover3G is a Mobile Substrate library that tricks Apps into thinking that they are on Wifi even though they are on 3G/edge/grps. In default configuration only Fring and AppStore are tricked. Through this App you can make VoIP calls over edge and also download Apps larger than 10 mb via 3g or edge.
VoIPover3G allows you to make VoIP over 3G or EDGE using the popular App Store App Fring or Truphone. it also allows you to install App Store Apps larger than 10mb, over the cell network.It achieves this by tricking the Apps into thinking you’re on a wifi network.
After install, by default, only Fring, Truphone, the iTunes Store, and the App Store are going to be tricked into thinking they’re on wifi. But You can also configure which Apps get tricked by editing /Library/MobileSubstrate/DynamicLibraries/VoIPover3G.plist and adding the App’s bundle identifier to that list. Removing VoIPover3G. Plist will make all Apps be tricked, which isn’t recommended.
Though not all providers may approve of this functionality and could block the necessary ports for VoIP calls, something this App cannot avoid or cheat. Also beware as your providers can also charge you for all this.
Overall its a great App for 3g users and works well. There are no bugs seen as yet.
Cydia is an Installer alternative, that Installs on Jailbroken iPhone 2.x… Info here