The ADTRAN DSU IV ESP is an all-rate data service/channel service unit (DSU/CSU) with an integral SNMP (simple network management protocol) agent and optional dial backup (DBU) capabilities. It provides an interface between digital data service (DDS) or 4-wire Switched 56 and the customer's data terminal equipment (DTE). The DSU IV ESP provides access to traditional dedicated point-to-point, multi-point, or frame relay services. The unit supports DDS rates from 2.4 to 64 kbps including 19.2 and 38.4 kbps, 4-wire Switched 56 operation, embedded SNMP and Telnet. Control port provides SLIP/PPP access to SNMP or VT 100 terminal configuration, there are two ESP option slots, 10BaseT Ethernet SNMP access port is available with ESP Ethernet card. The unit features automatic or manual dial backup with ESP DBU cards; options include 4-wire Switched 56, V.34, and ISDN. The unit responds to standard loopback commands from the telephone company central office. In addition, there are several built-in test capabilities. Complete control, configuration, and diagnosis are available through a 16-key keypad and a two-line by 16-character LCD display. A VT 100 terminal configuration and control mode is also available through the control port. Flash download capability allows installation of new features and enhancements.