Jio is the sister company of reliance. Recently the ceo of reliance, Mukesh ambani, launched an offer on 5th september, 2016 to give free 4g data and calling to everyone for 3 months, which was extended to 31st march, 2017, and maybe even further increased to 30june.
But with all the limits on data usage and slow speed people are not much interested in it now, like me. But its still good for people who didnt had internet access at all.