The popular way of loading a phone with airtime or credit is by buying a recharge card or voucher and then loading it on your phone with a USSD code. e.g *555*XXXXXX# for MTN subscribers. The other way is the digital method called Virtual Top Up (VTU). With VTU, the phone will be directly credited by the vendor and there will be no need for scratching a card or loading with USSD. The buyer will just receive an alert that his phone has been topped up.