Here is the configuration: First slot 101 is empty. 102-PDKU2, 103-PDKU2, 104 PDKU2, 103-RDSU1, 105-RCOU, 106-RCOU, 107 BDKU1, 108-PDKU2. I have worked on a lot of Toshiba, but all analog trunks. I appreciate all of the input. I have worked on mostly DK14s and CTX systems and even older models. This is the first DK424i. And believe it or not...Michigan is scarce on toshiba techs when it comes to the older systems.