The first edition of this book was published in 1992. Nine years later it had become
clear that a second edition was required because of the rapidly changing nature of
telecommunication. In 1992, the Internet was in existence but it was not the
household word that it is in the year 2001. Cellular telephones were also in use
but they had not yet achieved the popularity that they enjoy today. In the current
edition, Chapter 1 has been revised to include a section on the Internet. Chapter 10 is
new and it covers the facsimile machine; I had overlooked this important tele-
communication device in the first edition. Chapter 11 is also new and it describes the
pager, the cordless telephone and the cellular telephone system. These are examples
of a growing trend in telecommunications to go ‘‘wireless’’.
