It was recently announced that AT&T will now allow mobile applications to make VoIP calls using nothing more than the device’s 3G connection.

You should make note that prior to this announcement mobile applications, such as Skype for the iPhone, were only able to make VoIP calls using WiFi, but not anymore.

Following this announcement you can expect a whole influx of apps in the App Store, and other app stores, that allow for VoIP calling.

via engadget