All Indane Gas cylinders have a 16-digit customer ID number that is essential for gas bookings. Also known as the LPG ID number, this combination of numbers is unique to every customer and is printed on cash memos, previous gas booking invoic-es, or subscription vouchers.You will need to enter this 16-digit customer ID number while registering for the IVRS service for the first time. Once done, the automated system will save the ID and pair it with your mobile number, saving you fu-ture hassles. This number is also needed for online gas booking.