India's wealthiest man Mukesh Ambani announced the launch of Jio "intelligent" phone, offering life-long free voice calls bundled with 4G data streaming at an "effective price of zero".

Ambani, who had taken the telecom sector by surprise with free voice calls and data last year, announced the next leap at the company's 40th shareholder meeting.

The phone, targeted at 50 crore feature phone users in the country, will be available for pre-booking from 24 August on payment of a refundable security deposit of Rs 1,500. This deposit will be refunded after 36 months on return of the phone, he said, adding that the price of the phone will be "effective zero".

He used the occasion to introduce his twin children, Akash and Isha, who presented the phone features that include calls and text messaging on voice command, Internet surfing and cable to connect the device to TV to view content, including videos.

"JioPhone will make the 2G feature phone obsolete," Ambani claimed, adding that the company is looking to bring 5 million phones to the market a week.

The JioPhone will be available for user testing in beta mode from 15 August and for pre-booking from 24 August.