Viber - Free calls between iphone :

Viber iPhone is an application that enables free voip to call itself free iphone to iphone using wifi or 3G.
Here is a newcomer to the world of voip, Viber offers free telephone between iPhone and soon on BlackBerry and Android.

I am just passing the info because I have not tested Viber for the simple reason that I do not know anyone with an iPhone and using Viber.

Viber uses wifi or 3G to connect, once the application is installed, it will tell you which of your contacts, using the application. Your telephone number only is your ID Viber, no need to login or otherwise. With the push, you will be notified if someone attempts to get you through contace Viber.

For the rest, I leave you with the demonstration video:

to discover here: http://www.viber.com