Viber is an instant messaging and Voice over IP (VoIP) app for smartphones developed by Viber Media. In addition to instant messaging, users can exchange images, video and audio media messages. The client software is available for Mac OS, Android, BlackBerry OS, iOS, Series 40, Symbian, Bada, Windows Phone, and Microsoft Windows. A 64-bit Linux version is available in both .deb (Debian & Ubuntu) and .rpm (Fedora & openSUSE) package formats. Viber works on both 3G/4G and Wi-Fi networks. It first requires installation on a phone in order to work on a desktop operating system environment. Viber has over 100 million monthly active users from its 280 million global registered users.