https://itunes.apple.com/en/app/viber/id382617920?mt=8
With Viber, everyone in the world can connect. Freely. More than 300 million Viber users text, call, and send photo and video messages worldwide over WiFi or 3G - for free. Viber Out can be used to make calls to non-Viber landlines and mobile numbers at low rates. Viber is available for many smartphones and platforms.
On Viber, your phone number is your ID. The app syncs with your mobile contact list, automatically detecting which of your contacts have Viber.
・Text with your friends
・Make free calls with HD sound quality
・Share photos, videos, voice messages, locations, stickers and emoticons
・Groups with up to 100 participants
・Download stickers from the Sticker Market, making messaging fun!
・Push notifications guarantee that you never miss a call or message, even when Viber is off
・Support for the Viber Desktop application on Windows, Mac, Linux and Windows 8