Viber upped the competition a bit today by releasing a WP8 application of the VoIP application.
Viber is a direct competitor to Microsoft’s Skype application, Viber had a WP app that didn’t support voice calling but that changes today. Viber for WP offers both free text and photo messaging, as well as free VoIP calls, making it far more useful.
Viber has a user base of 150 million and is also on other platforms such as iPhone, Android, Blackberry, Symbian
and Nokia S40 handsets.