how to check data balance in airtel by message?
['Airtel Balance Check – *123#', '2G Data Balance Check – *12310#', '3G Data Balance Check – *12311#', 'Airtel 4G Balance Check – *1218#', 'Airtel Night Data Balance – *123197#', 'Airtel Special Offer – *121#', 'Airtel Special Offers and Rewards – *566#', 'Check 2G/3G Data Balance – SMS Data USE to 121.']