The Dual T1/PRI Module (P/N 1200314L1) is a member of the ATLAS 550 family of integrated access products and provides two channelized T1 or Primary Rate ISDN (PRI) interfaces. Each interface can operate independently in DS-1 or DSX-1 mode, and any port can serve as the primary or backup timing source for the entire system. This manual will provide information about the features, functions, and installation of the system.Â