Advanced subscriber line interface circuit using a per-line architecture

In the development of NTT's next-generation communications switching system NS8000, we developed a small low-power subscriber line interface circuit (SLIC) for analog interface terminals. This SLIC greatly decreases power consumption in the system by using a semiconstant current battery feed that limits the maximum line current. It has a simplified line test function and an off-talk service interface function, so there is no need for extra testing equipment for short line subscribers or for extra off-talk service equipment. For ease of maintenance, it has a per-line configuration, i.e. one line per card, and has a common card interface with an office channel unit (OCU). This paper describes the architecture for this SLIC and evaluates a prototype.