WhatsApp Messenger is an instant messaging app for smartphones that operates under a subscription business model. The proprietary, cross-platform app enables users of select feature phones to use the Internet to communicate. In addition to text messaging, WhatsApp can be used to send images, video, and audio media messages. WhatsApp has also started rolling out the much awaited voice calling feature. Locations can also be shared through the use of integrated mapping features. WhatsApp Inc. was founded in 2009 by Brian Acton and Jan Koum, both former employees of Yahoo!. The company is based in Mountain View, California and employs 55 people. It is in the process of takeover after Facebook announced its acquisition of WhatsApp Inc. on February 19, 2014, for US$19 billion. In October 2014, WhatsApp was the most globally popular messaging app with more than 600 million active users, with India alone boasting a user base of more than 70 million, followed by China’s WeChat (468 million active users), Viber (209 million active users), and Japan’s LINE (170 million active users). In January 2015 it reported surpassing 700 million users.