Viber is a mobile application that allows you to make phone calls and send text messages to all other Viber users for free! Viber is available over WiFi or 3G.
Viber uses your phone number as your "identity" and lets you make free Viber phone calls to any of your friends who have Viber. Once you've downloaded Viber, you will receive an access code via SMS or callback to activate Viber. The access code ensures that you are the real owner of the cellphone number you have registered and prevents others from obtaining your access code and placing calls with your caller ID. You can make calls and send texts via WiFi, as well as via 3G.