When I was in Burkina Faso, one of poorest countries in Africa, I could buy mobile phone cards form street vendors on every corner. Mobile telephony is indeed there.
What the article does not mention, however, is that the US is years behind in mobile telephony - not because of the lack of technological know-how, but as always, because of the fucked up organization of its economy. The Europeans developed the GSM system, which allows standardization, which is now widely adopted throughout the world. Africa certainly benefits from that system - without the "spillover" of GSM there would be no mobile telephony there.
In the US, by contrast, every provider uses what amounts to proprietary technology to maintain its monopoly in a market niche it occupies. As a result, we have a hodge podge of systems that are incompatible with one another - and none of which works outside the US (unless one purchases a special service for exorbitant amount of money).
This exemplifies the typical fucked up way of doing business in the US, whether it is mobile telephony, health care, transportation, or banking - corporate niche monopolies in the balkanized market that drive transaction costs (i.e. inefficiencies due to the high cost of doing business) through the roof while reducing cross-brand compatibility and universal access.
Wojtek