7.85 million visitors p.a. sounds like an interesting...

7.85 million visitors p.a. sounds like an interesting opportunity but targetting short-term subscribers isn't worth it as you have customer acquistion costs, costs for the physical SIM card and associated license fees which will probably reduce margins to a pretty unattractive level based on a customer relationship of 2 to 4 weeks at best. This would work if you sell the SIM for some $40 but then how many people would buy such instead of the regular prepaid SIM that is free of charge if you order a data bundle from $ 9.90 with it.