Here is a list of almost all BSNL prepaid balance enquiry viaUSSD(Unstructured Supplementary Services Data) Prepaid Enquiry ServicesDial *102# —>To know Last Call/SMS/GPRS DetailsDial *123# —>To know Your Mobile Number,Plan,Main Account Balance.Expiry Date etcDial *124# —>To know your Friends & Family NumbersDial *124*1# —>To know Limited & Unlimited Voice(STV401/STV501) detailsDial *124*2#—>To know Unlimited Local STV300