Telecom operator Reliance Jio has crossed the 300 million customers mark in two-and-a-half years of its operations, sources said. The milestone was reached on March 2. Jio became the fastest company in the world to achieve 100 million telecom subscribers in 170 days of starting commercial operation. During the ongoing IPL season, Jio is shown 'Celebrating 300 million users'. Jio on the matter remained unanswered.