Inter-working method for voice service in ATM switching system

This paper presents the inter-working method of public switched telephone network (PSTN) services over asynchronous transfer mode (ATM) based switching system. The existing synchronous transfer mode (STM) network may not be replaced entirely by the ATM network in the near future. It is important to add the inter-working functions to the ATM switching system to supply services provided by the existing networks. In this paper the inter-working subsystem (IWS) structure for accommodating PSTN subscribers in an ATM switching system is described. We also examine the software structure for call processing and control between heterogeneous switches and some specific aspects of the voice service in an ATM switching system