BSNL is the biggest ISP in India offering DSL as well Fiber Broadband. I am a BSNL Broadband since last 8 months and using the 499 unlimited plan in which I get 1Mbps Unlimited usage for one month.
The speeds are also same every time which is 1Mbps and harly fluctuate. In 499 BSNL also gives free unlimited calling to any network in India between 9 P.M to 6 A.M and on Sundays it is free for the daytime also.
Speed and the connection is good and quality of the connection is also reliable, the connection is not so good in rainy season as there is sometimes the problem in connecting but the BSNL staff is always there and normally resolves the problem in hours.
So overall BSNL Broadband is a good choice if you need unlimited internet with a fair speed
and also at a fair price.