After being acquired by Facebook last week, WhatsApp will introduce voice calling capabilities later this year. CEO Jan Koum revealed the details at a Mobile World Congress press event today, and stated the much requested feature will arrive before the summer.  This new addition will pin WhatsApp in a direct head to head battle with BBM, Line and other big name rivals that already have voice calling functionality.

WhatsApp will first introduce voice calling to its Android, iPhone and iPad apps, with Windows Phone and BlackBerry getting the nod at a later date. The company hasn’t revealed whether the new service will remain free or if it will be a paid extra.