Wikipedia
Nimbuzz
Nimbuzz is a proprietary cross-platform instant messaging aggregator for smartphones, tablets and personal computers developed by Nimbuzz B.V. Nimbuzz has 150 million users in 200 countries.
Under Vikas Saxena's leadership, Nimbuzz application enables users to enjoy free calls, instant messaging, social games, file sharing, and social networking on their mobile device. In addition; Nimbuzz offers discounted calling rates to most countries in the world. Nimbuzz garners more than 210,000 new registrations per day.