About the Author: Hu Hanrahan is Professor of Communications Engineering and Director of the Centre for Telecommunications Access and Services at the University of the Witswatersrand. He is a graduate of the University of the Witswatersrand, from where he also received his Doctorate. He has extensive experience of teaching in the subject area and is also active as consultant for a large number of companies and public utilities. His academic publication record is extensive over many aspects of communications technology.