BSNL is active in the whole of India except Mumbai and Delhi. Getting a BSNL SIM card has the same implications as getting any other phone connection in India. You will be pestered by telemarketers with constant spam text messages and calls. You can activate DND on BSNL to reduce this problem a little. Remember that while it is easy to activate DND on BSNL, it’s not a foolproof solution to get rid of SMS or call spam.
SMS START 0 to the number 1909. This will activate full DND on your BSNL number. You may also call 1909 and follow the prompts to activate full DND on your BSNL number.