Make Free calls with Google Voice on Your iPad, iPod touch, or iPhone via WiFi
Talkatone helps you to make unlimited FREE calls, send text messages and share locations using data connection on your iPhone, iPod Touch and iPad.
Talkatone uses WiFi or 3G connection only and doesn't use your cellular minutes.
Well, there you have it. It's very simple and just works, best of all the app is a free download from the Apple Store..I love it.