Viber rolled out an update to its Windows Phone 8  app to include  calls to landlines and mobiles, multiple file sharing and moreon Viber Out.

Viber, the popular instant messaging service, introduced new features to its backlogged Windows Phone 8 version of the app. The new update, which brings the app version to 4.1, includes support for the popular "Viber Out" feature. With this integration, the Windows Phone 8 app is aligned with its Android and iOS counterparts, and competes directly with it rival Skype, which offers similar services.

Viber Out on Windows Phone 8 smartphones will allow users to call landlines and mobile phones, as it does not rely on the other person to necessarily have the service installed. The app is still offered free of cost, but the Viber Out feature require users to buy credit. People making frequent international calls to friends and relatives can take advantage of the feature as, like Skype, Viber offers cheap calling rates. Call rates using Viber Out vary between countries.

"Viber Out has been a game changer for our users and allows them to rely on Viber for all their communication needs," GSM Arena quoted Talmon Marco, CEO of Viber, as saying in a statement. "With the addition of this critical feature to our Windows Phone 8 version, we are ensuring that the complete Viber experience is available on as many platforms as possible. This focus on cross-platform support is one of our most important commitments to our users."

In addition to Viber Out, the WP8 app supports multiple photo-sharing at the same time and also lets users send video messages, the changelog listed in Windows Phone Store's Viber app description reads. The updated app also supports seamless transfer of calls to hands-free Bluetooth devices.

The Viber app version 4.1 for WP8 handsets is available for download from Windows Phone Store or existing users can update the app, if it hasn't updated already, to enjoy the new features.