The R-ISDN channel unit has three LED indicators on the faceplate. A green ACTV LED indicates the plug-in card is busy. A steady red FAIL LED indicates that the plug-in card has failed, and a fl ashing red FAIL LED indicates illegal signaling. An amber LOOP LED indicates the plug-in card is in loopback.
Digital Data Service
The third-generation R-ISDN card (0110-0246) provides the Zero Byte Substitution option, allowing the system to carry ISDN DS0s over a groomed T1 using AMI line
coding. You can deploy the third-generation R-ISDN card as a 2-wire Digital Data Service (2w DDS application). When deployed in a 2w DDS application, the R-ISDN
card can emulate the 2B1Q Integrated Digital Subscriber Line (IDSL) signal. In the DDS mode, it supports the Zero Code Suppression (ZCS) and DDS latching loopback commands to maintain the DDS network.