The TSU 120 and 120e 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 120/120e supports applications combining digital voice and high-speed data. As interface requirements increase, the flexibility of the TSU 120/120e benefits the user with modularity through its expansion slot. The TSU 120/120e provides complete monitoring and control of the T1 network with embedded simple network management protocol (SNMP) provided through a SLIP interface. The TSU 120e also has a built-in 10BaseT Ethernet interface. To support critical data applications, the built-in V.35 interface on the TSU 120e can be converted to provide dial backup functionality during T1 failure conditions. This feature is supported by the interface and is available using an optional V.35 "Y" cable. Support for future growth, through the unit's single expansion slot, is a key feature of the TSU 120/120e. The ability to combine many types of plug-in and plug-on modules provides extensive combinations of voice and data interfaces. Several data modules are available for single and dual-port access to Frame Relay, DDS or Basic Rate ISDN services provided over T1 facilities. Voice modules are also easily integrated allowing access to analog voice circuits or additional PBX connections. As a fully functional T1 multiplexer, the TSU 120/120e supports all mixed-mode networking applications providing termination for circuits containing voice, data and video channels. Configuration and management of the TSU 120/120e is available through a variety of methods. The TSU 120/120e supports SNMP with Gets, Sets and Traps functionality through a built-in agent. ADTRAN MIBs support management for the TSU 120/120e and all installed expansion modules. For access to SNMP features, the TSU 120e has both a 10BaseT Ethernet and a SLIP (EIA-232) connection, while the TSU 120 has a SLIP interface only. In addition to SNMP, the unit utilizes the management capabilities found in optional software products from ADTRAN. For Windows-based management, the TSU 120/120e is compatible with the popular T-Watch PRO software package. For more complex network management systems, ADTRAN's ADVISION operates on an SNMP enterprise management system such as HP OpenView and provides full GUI configuration and control via SNMP.