Dial *446# from your Mobile handset. You will receive 1-2 SMS with all the balance info. You may receive USSD response if you have recharged recently. Works in Mumbai. Not working in Delhi as of yet.Finally MTNL hai to Sahi hai.
now only if we could have something like that for BSNL, also my problem is I dont have dialer ( using tablet) so anybody knows how can I send a message and get back the answer on BSNL ? I know for Docomo it is simple as sending BAL to 121 and it sends you SMs with everything