The trial in India\'s biggest corruption scandal has begun in Delhi with the questioning of the first witnesses.The scandal involves the alleged selling of mobile phone frequency licences for a fraction of their value.Former telecoms minister A Raja and MP Kanimozhi are among 14 people from telecoms firms or government who have been charged. All deny any wrongdoing.Auditors allege the mis-selling of the licences cost the exchequer nearly $40bn (£24.5bn) in lost revenue.The BBC\'s Sanjoy Majumder in Delhi says the scandal has gripped the country and deeply embarrassed the government.Last month, the federal Central Bureau of Investigation (CBI) framed charges including criminal conspiracy, forgery, accepting bribes and misuse of office.The trial, in a special CBI court in the Indian capital, is expected to be long and complex.Some 150 witnesses are expected to appear.The trial began with complaints from lawyers that the room was too small to take defendants, lawyers, family members and the press.However, proceedings got under way with the the judge calling the first prosecution witness, Anand Subramaniam, from Reliance Capital, part of the group owned by billionaire businessman, Anil Ambani.After four hours of questioning, group president of Reliance, AN Sethuraman, was called to testify.Mr Raja is accused of selling mobile phone licences to firms at a fraction of their real value in exchange for bribes in 2008.India has the world\'s fastest growing mobile phone market, with more than 700 million subscribers.Prosecutors say Mr Raja changed the eligibility criteria to favour certain firms.If found guilty, the defendants could face a maximum sentence of life imprisonment.The telecoms scandal has badly damaged the reputation of the government, which has been hit by a series of corruption scandals.Our correspondent says that in India legal proceedings can often take years, but with the public outcry over corruption, everyone is hoping that this trial can be resolved relatively quickly.