Interworking Real-time FoATM and FoIP

Digital Subscriber Loop (DSL) technology is being deployed between customers’ premises and central exchanges to unlock the access bottleneck to the Internet. Voice over DSL is supported using the Asynchronous Transfer Mode (ATM) Adaptation Layer 2 (AAL2). An Integrated Access Device (IAD) at the customer’s premises packetises the analog/digital voice and demodulated facsimile traffic into AAL2 packets. DSL terminates on a multi-service gateway at the central office, from where packetised voice and demodulated facsimile information can be costeffectively and efficiently delivered to a remote subscriber over a wide area IP network rather than Public Switched Telephone Network (PSTN). This paper describes the issues involved in developing a facsimile interworking function for real-time facsimile transfer between AAL2 and IP.