BSNL launched new 3G data plan for its prepaid users which allows users to get 4GB 3G data at just Rs.272. (effective price)
The plan works in this way.
Rs.68 for 1GB 3G data with 7 days validity
So if you do this recharge for 4 times a month you will get 4GB data for a month at effective price of Rs.272
( Rs.68*4 = Rs.272 ) total validity becomes 7*4= 28 days.
Please check with customer care to make sure that the offer is available at your circle.