The ISDN Quad Feeder Power Supply (IQFPS) provides a power source for up to four line interfaces. The power source to the device is a local battery or a centralized regulated power supply. It can operate in point-to-point and point-to-multipoint configurations as far as S interface is concerned. By the device microprocessor interface, each powered line is individually controlled and monitored. Therefore, overloads and faults are easy to detect and localize even in a large system. The status conditions detected by the device on each line that may be read by the microprocessor are :