From an unseen distance, Chipchase used his phone to pilot me through the unfamiliar chaos, allowing us to have what he calls a “just in time” moment. “Just in time” is a manufacturing concept that was popularized by the Japanese carmaker Toyota when, beginning in the late 1930s, it radically revamped its production system, virtually eliminating warehouses stocked with big loads of car parts and instead encouraging its assembly plants to order parts directly from the factory only as they were needed. The process became less centralized, more incremental. Car parts were manufactured swiftly and in small batches, which helped to cut waste, improve efficiency and more easily correct manufacturing defects. As Toyota became, in essence, lighter on its feet, the company’s productivity rose, and so did its profits. There are a growing number of economists who maintain that cellphones can restructure developing countries in a similar way. Cellphones, after all, have an economizing effect. My “just in time” meeting with Chipchase required little in the way of advance planning and was more efficient than the oft-imperfect practice of designating a specific time and a place to rendezvous. He didn’t have to leave his work until he knew I was in the vicinity. Knowing that he wasn’t waiting for me, I didn’t fret about the extra 15 minutes my taxi driver sat blaring his horn in Accra’s unpredictable traffic. And now, on foot, if I moved in the wrong direction, it could be quickly corrected. Using mobile phones, we were able to coordinate incrementally. “Do you see the footbridge?” Chipchase was saying over the phone. “No? O.K., do you see the giant green sign that says ‘Believe in God’? Yes? I’m down to the left of that.”

To get a sense of how rapidly cellphones are penetrating the global marketplace, you need only to look at the sales figures. According to statistics from the market database Wireless Intelligence, it took about 20 years for the first billion mobile phones to sell worldwide. The second billion sold in four years, and the third billion sold in two. Eighty percent of the world’s population now lives within range of a cellular network, which is double the level in 2000. And figures from the International Telecommunications Union show that by the end of 2006, 68 percent of the world’s mobile subscriptions were in developing countries. As more and more countries abandon government-run telecom systems, offering cellular network licenses to the highest-bidding private investors and without the burden of navigating pre-established bureaucratic chains, new towers are going up at a furious pace. Unlike fixed-line phone networks, which are expensive to build and maintain and require customers to have both a permanent address and the ability to pay a monthly bill, or personal computers, which are not just costly but demand literacy as well, the cellphone is more egalitarian, at least to a point.