Direct answer
Data reselling is buying mobile data inventory from a VTU platform or aggregator and selling it to customers at a margin. The customer sees a plan size. You see a route, a validity window and a risk that the route changes.
Plan types you will hear about
Nigerian resellers talk about SME, gifting, coupon and corporate routes. Those labels are industry shorthand. They are not a guarantee that the plan behaves like the same-sized plan in the official network app. Always tell the customer what they can verify on their phone after delivery.
Pricing hygiene
Do not copy a price table from another blog into your WhatsApp broadcast. Check your platform on the day you sell. Record the date.
Customer communication
State network, size, validity and that delivery is digital. If a plan is not shareable, say so before payment.