The ADTRAN ISU 2x64 is a standalone ISDN Service Unit that connects data terminal equipment to the ISDN network. The unit provides a cost-effective solution for the transfer of data and images over a single ISDN line. The ISU 2x64 can be viewed as a dual modem that supports two applications, simultaneously and independently, up to 64 kbps on each DTE interface. For high-speed applications over 64 kbps, a single DTE interface can achieve rates up to 128 kbps. Target applications for the ISU 2x64 unit include video-conferencing and audio broadcasting at 128 kbps, as well as dual modem replacement. The ISU 2x64 responds to loopback commands from the telephone company central office for network testing. The front panel of the ISU 2x64 consists of a two-line by 16-character display, seven LEDs, and a 16-button keypad. This allows for configuring, dialing, testing, and monitoring of the unit without a data terminal or test equipment. AT commands may also be used for configuration and status monitoring. In addition, the ISU 2x64 can be configured and maintained locally or remotely using a VT100 terminal interface. For remote configuration, the unit can be accessed over the ISDN or externally through the maintenance port on the back panel.