A new automated main distributing frame (AMDF) system is developed that reduces operating costs in metallic-cable main distributing frames (MDFs) used for communication networks. In this AMDF system, a robot inserts connecting-pins into the crosspoint holes of matrix-boards. This process allows jumpering to be completed within three minutes and the route-setting for line testing within one minute. The AMDF system provides approximately 2,100 office equipment cable-terminals. Parallel installation of several AMDF systems allows larger MDF systems to be constructed. This system reduces costs and achieves high reliability through three new technologies: high-density matrix-board, precision pin-handling, and a highly reliable system control. Test results for a prototype AMDF system confirm their effectiveness.