Back in 2007 BSNL made some really great move which marked a benchmarking event on India's wired broadband sector - to upgrade to wired broadband speed to 2Mbps minimum in most plans. Though that time was Manmohan Singh's era, many argue that main game was started during Atal Bihari Bajpeyi's time. Whatever the man stood behind BSNL's growth is actually Dayanidhi Maran, who was minister of communications and information technology (22 May '04 - 16 May '07).
When BJP came at the power, I personally thought that it will mark another success story of BSNL - however it is not, rather government is on the way of privatization of government assets like Air India is gonna be sold. BSNL may see the same fate with no proper planning and investment, though ministers keep pressing the bell that that will not happen.
Whatever it happens, the loss making state owned PSU telco - BSNL and MTNL will continue to make losses against the competitive mobile market of Airtel, Jio, Vodafone+Idea.
In February 2018, the telecom minister Manoj Sinha clarified that there is no plan at present to merge these two state owned telco but there will be steps taken to create synergy between two including effective utilisation of human resources as well as land and buildings.