The DS2196 T1 dual framer LIU is designed for T1 transmission equipment. The DS2196 combines dual optimized framers together with a line interface unit. This combination allows the DS2196 user to extract and insert facility data-link (FDL) messages in the receive and transmit paths, collect line-performance data, and perform basic channel conditioning and maintenance. The DS2196 contains all of the necessary functions for connection to T1 lines whether they are DS1 long haul or DSX-1 short haul. The clock recovery circuitry automatically adjusts to T1 lines from 0 feet to over 6000 feet in length. The device can generate both DSX-1 line build-outs as well as CSU line build-outs of -7.5dB, -15dB, and -22.5dB. The on-board jitter attenuator (selectable to either 32 bits or 128 bits) can be placed in either the transmit or receive data paths. The framer locates the frame and multiframe boundaries and monitors the data stream for alarms. The device contains a set of internal registers that the user can access and use to control the operation of the unit. Quick access via the parallel control port allows a single controller to handle many T1 lines. The device fully meets all of the latest T1 specifications.