Om Malik writes:
Necessity, they say is the mother of invention. It couldnt be more true in case of Africa, where pre-paid airtime is fast becoming the virtual currency for Pan-African trade, overcoming conventional currency exchange and lack of banking infrastructure. It started out as phone users in Nigeria, especially in the rural areas trading minutes, but then the transactions took a mercantile trend.
Instead of paying cash, people started paying in airtime. Minutes became moolah and since the trend has caught on, and is being used for cross border trade as well.