BSNL was among the most profitable companies of the country in time of NDA government.
Then came UPA/Congress government with Maran as telecom minister, then came legendary A Raja and now Mr "zero loss in 2G scam" Kapil Sibal is the telecom minister. With people like these in-charge, it is no wonder that BSNL is now among the biggest loss making company in India.
AFAIK, Maran, As the union minister he reduced mobile and landline call rates drasticaly which influenced the growth of telecom industry. And BSNL Broadband was introduced at the same time in 2005, on his tenure.