Dial 123# from your BSNL mobile to check balance and validity
Dial 124# to check main balance
Dial 1231# to check validity details
Send an SMS with BAL to 123 to get balance information
Use the BSNL Selfcare app to view balance and validity
Log in to the BSNL portal to check account details
Call BSNL customer care at 1503 or 1800-180-1503 for balance and validity details