New Delhi, June 1 (IANS): The mobile data traffic in India will grow 15 times by 2021 at a time when Internet of Things (IoT) is set to overtake mobile phones as the largest category of connected device by 2018 globally, a new report said on Wednesday.

Globally, there are nearly five billion mobile subscribers as compared to 7.4 billion subscriptions and in India the penetration level is at 80 per cent, the Ericsson Mobility Report noted.

"India grew the most in terms of net additions during the quarter ( 21 million), followed by Myanmar ( 5 million), Indonesia ( 5 million), the US ( 3 million) and Pakistan ( 3 million)," the findings showed.

Between 2015 and 2021, the number of IoT-connected devices is expected to grow 23 per cent annually, of which cellular IoT is forecast to have the highest growth rate. 

Of the 28 billion total devices that will be connected by 2021, close to 16 billion will be IoT devices.

"IoT is now accelerating as device costs fall and innovative applications emerge," Rima Qureshi, Senior Vice President and Chief Strategy Officer, Ericsson said in a statement.

"From 2020, commercial deployment of 5G networks will provide additional capabilities that are critical for IoT, such as network slicing and the capacity to connect exponentially more devices than is possible today," Qureshi added.

Western Europe will lead the way in adding IoT connections -- the number of IoT devices in this market is projected to grow 400 per cent by 2021. 

The report also highlighted the increase in smartphone subscriptions and said that by 2021, smartphone subscriptions will almost double from 3.4 billion to 6.3 billion. 

The report noted a dramatic shift in the viewing habits among teenagers. 

Over a period of four years (2011-15), a 50 per cent drop in the time teenagers spent watching TV/video on a TV screen was reported -- in contrast to an 85 per cent increase in those viewing TV/video on a smartphone.