WhatsApp will gain voice calling abilities in the second quarter of this year. CEO Jan Koum revealed that the much-requested feature will arrive before the summer, at a press event at Mobile World Congress in Barcelona.

The messaging service, bought by Facebook for $19 billion last week ($16 billion in cash and $3 billion in add-ons), will go head to head with BBM, Line and other big name rivals that already have voice calling functionality.

READ: WhatsApp acquisition: Why did Facebook spend more than $16bn on a messaging app?

WhatsApp's Android, iPhone and iPad apps will get the new feature first, with "some Nokia and BlackBerry phones" getting an upgrade at a later date. The company hasn't revealed whether the new service will remain free or if it will be a paid extra.

The Facebook acquisition was something of a shock when it was announced last week, but Koum says that it will not change the way WhatsApp conducts its business. "There are no planned changes and we will continue to do what we set out to do, even after the acquisition closes," he said. "Still no marketing."