BSNL( bharat sanchar nigam limited) one of the biggest network of the india.
bsnl 3g moblie network is so good in india. At present, 4g network has been lounched in india, while bsnl is offering a good plans.
₹333 in 3GB per day 3g data for 90 days validity. Its very inexpensive rate of that plan.
The bsnl boardband plan is also good.so that bsnl network is one of the successfull network in india