These calls are not free but come at very affordable rates. Viber Out allows you to call non-VoIP users (landlines or mobile phones) directly. Once you are done, you can call and chat to your heart's desire at no cost. Next, install the Windows desktop client and sign in to sync your contacts across both devices. Viber can only be used on a Windows PC if you first install Viber on a mobile phone (Android iPhone, Blackberry Symbian, and Windows Phone apps are available). Viber and Whatsapp have effectively killed the traditional mobile SMS market, thanks to their ease-of-use and increasing data coverage. You can even video chat with up to 100 contacts at once! The package is completed with a simple UI. All of your phone contacts with the app installed can voice call, chat, send SMS and photos, as well as video calls. Viber/Whatsapp is different from Skype in that you can communicate with all your mobile phone contacts who are also using the service, not just your skype contacts.

Viber is competing with Whatsapp to be the most popular cross-platform/cross-device messaging service worldwide. It makes it easy to multitask and get on with work while still communicating with your contacts.

Viber PC client brings the convenience of the mobile application to your PC, so you can stay connected even if you don't have a mobile phone. Viber is a popular voice-over IP messaging service that offers free, unlimited access to your smartphone and PC.

Viber for windows phones