Ken Banks writes on what happens when cell phones become ubiquitous in areas with terrible and unreliable electric power.

Users in many African countries - and not just those in rural areas - face similar problems [involving access to electricity]. In Uganda, this "charging challenge" is being met head-on by a growing band of local entrepreneurs and business people.

Rural users are able to charge their phones from a car battery (top), charged up by a local entrepreneur when power is available, or charged in a nearby town with better supply and transported back. In urban areas, where grid power is generally more reliable, kiosks (below) dotted around local markets provide charging services to passing customers.

The spread of mobile technology in developing countries has opened up income-generating opportunities on a massive scale. But what is most interesting is how local entrepreneurs have taken advantage of this growth using their own skills and ingenuity. According to the Uganda Communications Commission, the telecoms sector there provides direct employment to a little over 6,000 people. Indirect employment - which includes mobile charging entrepreneurs, airtime vendors, accessories sales-people and mobile repair shops - comes to a staggering 350,000.

Boda Phone, Kampala, Uganda: "I met this phone operator off Kampala Road this afternoon, who was riding round on this bike. Luckily he was a fellow Liverpool supporter so we hit it off straight away – and he let me take a photo of his BodaPhone setup. Pretty neat, and with a spare ba