A few days ago I shared USSD code for buying airtime straight from your GTB account balance, and I would be sharing something similar today. If you own a First Bank account and you want to simply dial a short-code to buy airtime for your phone straight from your First Bank Nigeria account then the USSD code to use is very simple.
To do this, simply dial *894*Amount#
For example *894*500# should be dialled to purchase NGN500 airtime.
Please, note that the code should be dialled from the phone number that is tied to your First Bank Nigeria account.
As at the time of writing this, there is no option to buy airtime for other phone numbers not attached to your bank account, but that should be on its way pretty soon though.