AUDIO SERVICES FOR AN ASYNCHRONOUS TRANSFER MODE NETWORK

The adoption of asynchronous transfer mode (ATM) as the target technology for the broadband ISDN (B-ISDN) poses many questions for network planners and service providers. This paper addresses the issue of how existing and future audio services are carried on an ATM platform, highlighting the potential and flexibility of ATM over existing switching technologies. Voice telephony is the mainstay of BT's revenue both nationally and internationally, and so it is very important to migrate this to an ATM network effectively A technical solution is proposed which addresses many of the doubts which have been expressed for the suitability of ATM for existing plain old telephony services (POTS). But telephony is just the tip of the iceberg. ATM could offer services such as dial-up CD quality music, wideband voice circuits with very high quality sound, enhanced voice (e.g. for mobile telephones), conferencing facilities, and of course, multimedia services where video, data and voice are available. These potential services are reviewed along with some details of the coding required. The paper then proposes some possible network architectures for customers focusing on the technology used and the interworking issues with the existing public switched telephone network (PSTN). The final section investigates quality of service for audio services with particular reference to delay and echo which have to be met within the UK. Many people see ATM as an overrated pipe dream. Certainly there is a lot of hype, but this paper shows that an ATM platform call deliver the existing services, and is flexible enough to allow BT to carry future applications.