I've long been aware of the trend towards bypassing landlines in Africa, in part due to the cost structures - while not apparent in developed countries where the vast cost of building out landline networks have been absorbed over a century of to a large extent heavily regulated telephone companies.
Mobile networks are today cheaper to build out, and as a result they've already far bypassed landline usage in many developing countries.
This article over at BBC News isn't new, but it had escaped me until today. It covers the growth levels, and also interestingly shows that growth in mobile usage can also be linked to increases in GDP in Africa.
Now, without seeing the study it's hard to judge whether the numbers say that a country with higher growth is likely to see higher mobile usage, or the other way around.
On the other hand, it's quite logical that as mobile usage grows, it fuels more growth in the economy, thanks to improved communication and the ability to conduct business more effectively.