As far as my experience and knowledge with BSNL goes, it should be of this order.20 GB worth download at high speed ( my guess at 4Mbps) and after that whatever you download would be charged at 0.10 or 0.50 paise per MB.Uploads - no one really is worried about that, you can upload to infinity and beyond.It is not a night unlimited plan. Example : if you are on a 2Mbps line and you are paying 2200 rupees a month. The first 20GB you download and 20GB you upload will be at 2Mbps speed. After that it goes down to either 256 Kbps or 512 Kbps depending on what plan you chose.For every extra download you make you have to pay at around 0.10 or 0.20 or 0.50 paise per MB.So, be careful and try not to click on everything that you come across.