The ADTRAN ACT 1900 is an intelligent D4 channel bank intended for central office (CO) installations where intelligence, low-cost commonality of channel units, and high reliability are desired. Based on industry standard D4 technology, the ACT 1900 accommodates a wide variety of low-cost channel units from numerous suppliers. Intelligent ADTRAN channel units, which provide DS0 performance monitoring and remote provisioning capabilities, complement the advanced functionality of the ACT 1900.The ACT 1900 benefits from a reduced common equipment section consisting of only three common units: Bank Controller Unit (BCU), Line Interface Unit (LIU), and Power Supply Unit (PSU). The BCU is an intelligent controller for the bank providing non-intrusive communications to the channel units, control of the multiple communications ports, and storage of alarm, provisioning, and performance information. The communications ports consist of a local craft interface for terminal control, a modem access port, and an RS-485 interface to the ADTRAN Site Manager for management of multiple banks.