Direct answer
Airtime reselling uses the same VTU rails as data, but the product is simpler and the margin is usually smaller. Customers expect instant credit. A delayed airtime order feels like a failed order.
Discount vs data margin
Platforms often advertise a percentage discount on airtime. That number changes and can differ by network. Record the discount you actually received on a test purchase rather than repeating a homepage claim.
Operations
Keep a dedicated float. Reconcile platform wallet, bank account and customer debt daily if you sell on credit — most beginners should not sell on credit.