Apple updated the terms of the SDK to allow VoIP calls over 3G. Sinds Apple changed the terms companies are creating VoIP apps fast. For example take a look at Fring, Fring allows you to make voice calls, video calls and chat using the 3G  network and Wi-Fi. Unfortunately not all network providers except you to use VoIP “yet”. » Fring: Make Voip Calls Over 3G