Guarantee Trust Bank is currently given given out an awoof of N737 worth of airtime when you recharge your SIM with the popular GTBank USSD code *737#.
According to the official promo announcement made on the banks twitter handle which reads below.
Get back N737 when you recharge N737 airtime for your friends and family
This simply means, when you recharge another line from your regular GTBank registered phone number, you will get extra 737 Naira worth of airtime to make calls and browse.
To recharge, dial the GTBank popular USSD code *737# and follow the directions on the screen. After that, your awoof data will be sent to your main line linked to your bank account that is, the phone number you used to get your GTBank alert.