The TSU 120 are modular, full-featured T1/FT1 multiplexers designed to support a wide range of end-user applications. Equipped with both a synchronous V.35 DTE interface and a DSX-1 PBX port, the TSU 120 supports applications combining digital voice and high-speed data. As interface requirements increase, the flexibility of the TSU 120 benefits the user with modularity through its expansion slot. The TSU 120 provides complete monitoring and control of the T1 network with embedded simple network management protocol (SNMP) provided through a SLIP interface.