Poorly researched article that doesn't explain much .
TRAI reports two numbers: total subscribers, total active subscribers. There's a separate data set that reports total unique subscribers, which is approx 800 million the last I checked, i.e. that many people have at least one cellphone. TRAI updates the active subscriber data periodically, so that the total count drops every few months, e.g. Nov vs Dec data.
Now onto smartphones - the market is 'far from saturated with them'. Ok how many ? Why quote PC numbers here ? Off Wikipedia: https://en.wikipedia.org/wiki/List_of_countries_by_smartphone_penetration
India has 500 million smartphones. Why not mention it - '500 million' and 'far from saturated' sounds a little ironic ?
India has 1.35 billion people. 'Millions of Indians' means little. That many... just burped. But there are numbers that are still a lot, and 500 million is one of those.
Look at the coverage map: https://www.nperf.com/en/map/IN/-/-/signal/?ll=22.12215821805932&lg=82.785&zoom=4 . The three majors are saturated with their LTE coverage. Only the state run BSNL has 2G/3G, partly because its tied to railway connectivity, and the railways wants dedicated 4G spectrum to complete the move.
The 5G story is a LOT more nuanced than the author understands. India does not want to repeat the 4G story in 5G, i.e. it will NOT buy western or Chinese 5G standard gear. India just had the 3GPP merge the domestic 5Gi standard.
This is the future of xG telephony - India and China with their sheer market sizes will have their own standard and there's not going to be outbound licensing revenue streams here. The money and technology stay at home.
It's simply a matter of time before 5Gi phones saturate the market. It's not like people are complaining en masse about LTE data speeds.