The BSNL mobile operators are the largest and the widest network provider indeed its true but the network is never available where it is required the most. My fathers shop is in the market where there are more than 50000 - 60000 shops but BSNL network is never available there. But whenever we go to rural places we find only BSL that’s true, but what is the use if you do not provide service in urban areas.
The customer service is ok but once I recharged my phone with talktime worth 250 and I got credited with only ₹25. When I went to complaint they told its a technical problem and my talktime never came back. Overall their customer service is poor. The best thing about BSNL is its price of tariff plans. They charge real less( not less than JIO) , because it is government company. So overall I would rate BSNL 3/10.