The ADTRAN ISU 512 is a standalone ISDN Service Unit that connects data terminal equipment (DTE) to the ISDN network. The ISU 512 is specifically designed as a low-cost solution for applications such as video-conferencing, T1 backup, LAN/WAN connectivity, and high-speed file transfer.? ?The ISU 512 is designed as a cost-effective inverse multiplexer for 384 kbps videoconferencing. Some video-conferencing products operate in a dual port mode. The ISU 512 is designed to operate in a dual port mode making it backward compatible with videoconferencing systems utilizing two Switched 56 DSUs or a dual port ISDN terminal adapter. The ISU 512 connects directly to the ISDN network using up to four Basic Rate ISDN (BRI) lines. By terminating four BRI circuits, the ISU 512 can create an aggregate bandwidth of up to 512 kbps which can be used to backup a T1 circuit. Since ISDN is a switched digital service, bandwidth can be established and utilized on an as needed basis. Therefore, the ISU 512...