f ATM. References Freeman, R.L., Telecommunications System Engineering, 3rd ed., New York: John Wiley & Sons, 1996. [2] Halsall, F., Data Communications: Computer Networks and Open Systems, 3rd ed., Read- ing, MA: Addison-Wesley, 1996. [3] Tanenbaum, A. S., Computer Networks, 3rd ed., Upper Saddle River, NJ: Prentice Hall, 1996. Introduction to Telecommunications Network Engineering Comer, D. E., Internetworking with TCP/IP: Principles, Protocols, and Architecture, 4th ed., Upper Saddle River, NJ: Prentice Hall, 2000. [5] Ericsson Telecom, Understanding Telecommunications, Vol. 2, Lund, Sweden: Ericsson Telecom, Telia, and Studentlitteratur, 1998. [6] Dutta-Roy, A., "An Overview of Cable Modem Technology and Market Perspective," IEEE Communications Magazine, June 2001, pp. 81-88.. Grilo, A., P. Estrela, and M. Nunes, "Terminal Independent Mobility," IEEE Commu- nications Magazine, December 2001, pp. 34-71. Future Developments in Telecommunications The 1990s were marked by rapid development of telecommunications serv- ices, technologies, and business. The two major areas of huge expansion were the Internet and cellular telephones. Most professionals in the telecommuni- cations business did not expect this kind of growth at the beginning of 1990s. It is difficult to estimate which new services will gain market accep- tance and which will not be successful. A technology must be available but, in addition, success depends on many other things such as how attractive the service is, how the new services are launched and charged, and what alterna- tive services are available. In the following sections we look at some future development areas. 7.1 Information Networks The success of the Internet was based on the graphical user interface devel- oped at CERN that was introduced in Chapter 6. As we saw it was not a technical revolution but it made Internet service more user friendly and attractive to the public. Internet network technology itself was more than 10 years old and it had proved to be capable of providing global