Popular instant messaging platform Viber, Inc. said its recent release of Viber 4.1 for Windows Phone 8 brings its "Viber Out" calls to the Windows smartphone platform for the first time.

Viber Out is a service that allows Viber users to call any landlines and mobile phone number at low rates. It enables Windows Phone 8 users to call any phone number with Viber.

Viber is a leading mobile communications platform offering free messaging and HD-quality phone calls.

With the inclusion of Viber 4.1 for Windows 8, Viber is now on iPhone, Android phones and tablets, Mac, Linux, Blackberry, Windows, Nokia S40, Symbian, and Bada devices over 3G/4G or Wi-Fi connections.

Callers on Windows Phone 8 using Viber 4.1 can make affordable calls to friends and contacts that have landlines or to phones that don't have Viber. The update also brings several key Viber features to Windows Phone 8.

Viber's strategy has been to support as many platforms as possible in order to expand its user base. Talmon Marco, CEO of Viber, said Viber Out has been a game changer for Viber users since it allows them to rely on Viber for all their communication needs.

"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," Marco said.

Viber was developed by Viber Media, a pioneering mobile messaging and VoIP company founded by Israelis. Last February, Viber was bought by Japanese e-commerce and Internet giant Rakuten, Inc. for $900 million.