At their peak in 2006 and 2007, mobile operators were the wonder kids of India Inc, seeing rapid growth and generating immense wealth for shareholders.
This was despite the fact that their rates to millions of new customers joining the network every month were among the world's lowest.
It seemed nothing could go wrong.
For a while, Bharti Airtel and Reliance Communications, the two leading operators, joined the league of India's most valuable firms.
Five years later, after a haircut, shareholders have deserted the sector. And, the majority of the telecom industry is reeling.
As of March, the industry had accumulated total debt of Rs 1,85,720 crore (Rs 1,857.2 billion), two and half times the debt four years earlier, according to estimates by PricewaterhouseCoopers.
It expects the debt to rise to about Rs 4,00,000 crore (Rs 4,000 billion) by the end of March 2016, provided the coming 2G spectrum auction sees aggressive bidding and the government goes ahead with the Telecom Regulatory Authority of India's recommendation to re-farm 900-MHz spectrum in 2014.
Experts