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This article describes and evaluates the design and performance of a newly developed support system for subscriber optical fiber cable operations. The former support system, which was capable of automatic remote testing without any interruption in service, was introduced, and could decrease the amount of time for test work during cable construction by 75% and repair time by 50%. In addition to this feature, the new system allows one test controller to be shared by several offices. Moreover, carrier equipment faults are clearly separable from user equipment faults in the test results. Consequently, the application possibilities for the new support system increase along with the precision of identifying faults. Our evaluation of the new system's functions is based upon tests performed on a system prototype assembled specifically for this purpose. IntroductionFiber-optic transmission systems have played a vital role in meeting customer demand for various services. NTT has introduced Central Terminal / Remote Terminal (CT/RT) systems, as well as singlemode optical fiber cables with multiple fibers, into subscriber loops. As subscriber networks have rapidly expanded, the pace of optical fiber installation has also picked up dramatically. As a consequence, "IT faces several problems related to the operation and maintenance of optical fiber lines in the outside plant. The time required for testing and maintenance of optical fiber cables has increased dramatically alongside the growth in the quantity of installed optical fiber cable. Manual testing procedures are time-consuming.Using traditional testing methods, it is difficult to distinguish between fiber line faults and transmission equipment faults. It takes time to determine the nature and location of problems. which means a less consistently reliable system for customers.As fiber optics subscriber loops have become more extensive, and the number of optical fiber cables has increased, the administrative paperwork required for handling optical fiber plant information has grown to a point where it threatens to overwhelm attempts to manage it. An effective operation system is necessary to support construction and maintenance of fiber optical subscriber networks, and to make fiber optical subscriber networks free of the problems mentioned above. Such a network should have its own operations system capable of monitoring inservice fiber lines in order to ensure network reliability. To this end, NTT has developed AURORA( 1)(2)(3) (Automatic optical fibeR OpeRAtions support system), which was introduced into the Tokyo, Kansai and Kyusyu areas for commercial use in 1990. So far. the system has been a success. AURORA has made it possible to reduce optical fiber cable construction and maintenance work and centralize facilities management work. Test work during cable construction was decreased by 75% and the optical fiber cable repair time by 50%.However, it is very difficult to accurately forecast future demands for optical fiber. so the proper scale of the optical fiber networ...