MOBILE money in Africa comes in different flavours. The sophisticated sort, exemplified by services such as M-Pesa in Kenya, allows account-holders to transfer legal tender electronically to fellow account-holders by entering commands on a mobile phone. Popular though such services are, they have not stopped an older form of mobile money flourishing. This sort uses pre-paid mobile-airtime minutes as a de facto currency that can be transferred between phones, exchanged for cash with dealers who rent out phones, or bartered for goods and services.

Pre-paid minutes can be swapped for cash or spent in shops most easily in Côte d'Ivoire, Egypt, Ghana and Uganda, says Chris Chan of Tranglo, a Malaysian firm that facilitates "airtime remittances" to mobile phones. Airtime is commonly used as money in Nigeria, too. Hannes Van Rensburg, Visa's boss for sub-Saharan Africa, says this is partly because regulators there have made it difficult for banks to offer the newer form of mobile money.