The Chief Executive of Facebook says he has no plans to make changes to the way 'WhatsApp' operates. Mark Zuckerberg says the €14 billion he paid for the messaging service last week is quite a good bet.

Zuckerberg (29) made the remarks during an address at the Mobile World Congress in Barcelona, Spain.

He says his vision is to keep WhatsApp the same with no plans to start storing the data sent by users.

Earlier WhatsApp announced its launching free voice calls. It says the new calls system will be up and running by the second quarter of this year.

The announcement was made by the company founder Jan Koum at the same event in Barcelona.

The compnay has meanwhile apologised after being unavailable for several hours on Saturday night. The team behind the app blamed "server issues" for the down-time.

More than 450 million people use the service worldwide each month.