DESC: ADTRAN designs, develops, and manufactures ADvanced TRANsmission products for high-speed digital communications. ADTRAN commitment to total customer satisfaction requires continually developing and improving products to meet changing needs while maintaining the highest level of quality. That's why a complete collection of modular and scalable ADTRAN solutions is provided with a broad range of options for management, network, and local loop interfaces.??ATLAS 550 user interface module provides four T1 PRI or DSX-1 interfaces.