An implementation of voice message connection control for PSTN subscribers in ATM switching system

The IWF (inter working function) interworking between asynchronous transfer mode (ATM) and existing synchronous transfer mode (STM) network should ensure the continued support of services and applications currently provided. As the ATM switching system accommodates an STM switch, in order to give the same quality of voice services to the telephone users, the interworking system should cover various technical issues such as voice quality, echo control, partially filled cell, ATM adaptation layer (AAL) for voice, tones and announcements. The voice message connection control, which is the subject of this paper, is one of the essential technical issues for voice services. We present the design and implementation of voice message connection control technology which is used to announce the causes of call failure in the ATM switching system accommodating the public switched telephone network (PSTN) and narrowband ISDN (N-ISDN) subscribers.