Implementation of an ATM switch for PSTN/N-ISDN services

ATM has the capability of carrying various types of services, and broadband networks based on it have already been in commercial operation in some countries. But it is considered that ATM is not suitable for switching and transferring low-speed CBR services such as 64 kbit/s voice and other traditional narrowband services, because the large packetization delay induced by the ATM voice adaptation will seriously affect the quality of voice. In this paper, we present an ATM switching system for PSTN/N-ISDN services in which we adopt the composite cell adaptation method to reduce the packetization delay in order to satisfy the delay requirements of STM switching systems. Some key parameters have been measured in the realized system, and the results prove that this switching system guarantees perfect voice quality and high bandwidth efficiency.