Japanese firm Rakuten has bought Cyprus-based mobile app messaging company, Viber Media.

The app, which is available over WiFi or 3G, allows users to make phone calls and send text messages to all other Viber users for free.

Tokyo Stock Exchange-listed Rakuten, said it decided to acquire Viber for $900 million, in a bid to strengthen its global platform through the use of Viber’s range of customers in the company’s e-commerce and digital contents services.

A spokesman from Rakuten said the firm aims to be the global number one internet services company, and in addition to its e-commerce and internet finance services, this new acquisition will allow it to build on several digital content services, and advance into new markets..

“In the past, consumers had been using conventional televisions and fixed line telephones for contents as a means of communication, but this has been shifting to mobile contents and apps,” a Rakuten spokesman said.

“Viber’s globally popular messaging service is seeing a rapid increase in numbers of registered users, and this will strengthen our digital strategy.”

Viber, which competes against the likes of the Whatsapp and WeChat messaging apps, has also been experiencing a ‘rapid’ growth in its numbers of users, especially in emerging countries.

Messaging and VoIP service Viber, has approximately 280 million global registered users, and more than 100 million monthly active users.

Rakuten, which also owns display and retargeting company Rakuten MediaForge, affiliate marketing network Rakuten LinkShare and online retailer play.com, also has investments in Pinterest.

According to Bloomberg, Rakuten shares fell 9.5% in Tokyo trading after announcing the $900 million deal.