This is a good two part series on the origins of Indian conglomerate Reliance and its extremely successful telecom division, Jio: Part I, Part II.

I wasn't in India in 2016, when Jio had started to take off, so I hadn't realized how it had transformed internet access for Indians:

[Jio's] data plans were so incredibly cheap, they undercut the incumbents by more than a third. At launch Jio's 4G network already covered 18K cities and towns, 200K+ villages. Within 6 months, the company was promising to cover 90% of India’s population. Ambani said he wanted to get to 100M customers as soon as possible.
Jio's impact on the sector since it first arrived on the scene has been massive. 4G is now the default network for most of the country, and Jio carried ~70% of the country's 4G traffic in 2019. Its competitive pricing in a bid to gain market led to broad reductions in ARPU across the sector, resulting (unsurprisingly) in increased consolidation. Reliance's own share gain has been pretty amazing. It now boasts 388+M customers.