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Voice and Data Convergence The subject of this book is all about the convergence of voice and data services into a new world of advanced (and hopefully useful) applications that will enrich the way people work and communicate. So a specific chapter entitled voice and data convergence could jar a little with the reader, however, this chapter was prompted by the words in the International Telecommunications Union telecommunications (ITU-T) specification ‘‘The need to integrate both circuit- and packet-transfer mode into one universal broadband network’’ | Next Generation Network Services Neill Wilkinson Copyright 2002 John Wiley Sons Ltd ISBNs 0-471-48667-1 Hardback 0-470-84603-8 Electronic 7 Voice and Data Convergence INTRODUCTION The subject of this book is all about the convergence of voice and data services into a new world of advanced and hopefully useful applications that will enrich the way people work and communicate. So a specific chapter entitled voice and data convergence could jar a little with the reader however this chapter was prompted by the words in the International Telecommunications Union telecommunications ITU-T specification The need to integrate both circuit- and packet-transfer mode into one universal broadband network . It is interesting to reflect that what we now start to see becoming achievable through Internet Protocol IP was stated as a goal in an ITU-T specification in the late 1980s. One of the difficulties in finding a place for Asynchronous Transfer Mode ATM in the first part of the book was that ATM is a packet technology but has a circuit switching heritage so if the reader will forgive me I have chosen to pick up ATM under a chapter all of its own under voice and data convergence. The simple statement amongst others in gave rise to the specifications for Broadband ISDN B-ISDN and through the work of the ATM forum the specification of asynchronous transfer mode. This chapter explores ATM as a key enabler to convergent communications and applications. ATM has suffered against transport control protocol Internet protocol TCP IP as TCP IP started getting all the attention and ATM seems to have been backwatered as a transmission mechanism. That s not so say ATM isn t a success quite the contrary ATM has had a 94 VOICE AND DATA CONVERGENCE resounding success and in fact has found its way into public data networks in a big way and may continue to gain success as a mechanism for creating connection-oriented paths through a network that carries Multi Protocol Label .