The ADTRAN NT1 ACE provides the network termination for 2B1Q ISDN basic rate service. The NT1 ACE provides a 2B+D basic rate interface between the subscribers' terminal equipment and the ISDN network. Basic rate ISDN consists of two 64 kbps B channels and a single 16 kbps D channel. Connection to the ISDN network is made with a U-interface. Connection to the subscribers' terminal equipment is by an S/T-interface. The U- and the S/T-interfaces conform to ANSI and CCITT standards and perform all Layer 1 functions. The NT1 ACE is designed with aesthetics as well as functionality in mind. The unit is enclosed in an attractive, durable plastic housing appropriate for desktop use. The NT1 ACE is powered by the wallmount power supply included with the unit. The wallmount power supply provides up to 8.9 watts of power for terminal equipment. The NT1 ACE monitors the S/T-interface for overcurrent fault conditions. In the event of such a condition, the unit automatically limits the amount of delivered current until the fault condition is removed.