The ETU-01 is a highly reliable 2Mbps G.703 / G.704 interface converter. The unit has a single G.703 port presented as two 75 Ohm BNC connecters as well as 2 120 Ohm connectors presented as RJ-45 and DB-15. The ETU-01 supports a wide variety of interchangeable interface modules including, X.21, V.35, RS530, RS449 and an Ethernet 10BaseT bridge / router module.

The ETU-01 provides a simple method of gaining access to 2Mbps E1 (and fractional E1) leased lines. The ethernet bridge module allows direct connection of an ethernet striaght into E1 services. Alternativley one of the other modules could be used to connect a variety of DTEs to E1 or fractional E1 systems.

The ETU-01 features V.54 diagnostic capabilities for performing local loopback and digital loopbacks. The operator at either end of the line may test both the ETU-01 and the line in the digital loopback mode. The loopback is controlled by either a manual switch or by the DTE interface for V.35 and RS530.

The ETU-01 has a built in Bit Error Rate Tester (BERT), this can be operated via a front panel switch that activates an internal 511 bit pseudo random test pattern, according to ITU (CCITT), for direct end to end integrity testing. The Err indicator flashes for each bit error detected.