Raja, who was in charge of the country’s telecommunications from 2007 to 2010, is the key figure in the 2G case, although well-known MP Kanimozhi – who is known by one name – senior industry executives and government officials are also in the dock.
They face a maximum sentence of life imprisonment.
The scam allegedly involved the sale of second-generation (2G) licences at far below their commercial rate to certain companies, costing the government up to 29.4 billion euros.
At the start of proceedings lawyers protested at the choice of a tiny courtroom for one of India’s biggest trials in years.
"We can't hear what the witnesses are saying," complained defence lawyer Majeed Memon. "The administrators of the court should do something about providing better ventilation and seating facilities. How can you conduct such an important trial in such a shabby manner?"
The prosecution is likely to focus on accusations that when allocating the licences Raja favoured Swan Telecom, alleged to be a front for Ambani's Reliance group, and another company called Unitech Wireless.