In 2016 Nov, Jio did amazing job by giving 4G data free for almost 4 months(10GB per day was limit,i guess. Also, 2G speed afterwards). It then introduced cheapest 4G 1GB/day plan for ₹400/3 months( 5.37 USD for 3 months) .Few other cellular network companies gradually went bankrupt, but others too introduced cheap plans(comparable to jio plan). This way,they revolutionized Indian internet and i am thankful to them for providing Cheap and Good internet.
But,it certainly was a curse for other ISPs(only jio,airtel(which bought few rival companies like tata docomo), and idea/Vodafone(both which got merged), state owned BSNL are remaining.