nstream, foundation-level technology. Starting in the late 1800s with the parallel work of Marconi and Bell, radio and telephony wandered down different paths until fairly recently, when they converged and joined forces, leading to the development of cel- lular telephony. The story doesn't end with cellular telephony, however. Today, mobile users are clamoring for the ability to extend the reach of LANs, video- conferencing systems, medical image devices, and database access, with- out having to deal with the restrictions of a copper tether. Developing nations have realized that with cellular technology, telephony infra- structures can be installed in countries in a fraction of the time it takes to install a wired network. In fact, my work in Africa has shown me the degree to which humans demonstrate their ability to innovate in the face of technological challenge. In August 2004, I traveled to Johannesburg, South Africa, to work on a project with one of my clients there. When the Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Access Technologies Access Technologies Figure 6-11 Metal shipping container converted to a central office and calling center in Africa work was complete we took a trip into the bush to do some wildlife pho- tography, and on the way to the game area we passed the most remark- able sight. The one word that comes to mind when I think of South Africa-or Africa in general, for that matter-is vibrant. I have never seen, in any of the countries I travel to, the degree of entrepreneurial vibrancy that I regularly see in Africa. As we approached the intersection of two dirt roads in the middle of the bush northwest of town, I saw the usual gag- gle of people standing on all four corners of the intersection, selling the usual collection of fresh fruit, roasted corn, cell phone chargers, toys, and newspapers. On my left, a row 