https://www.cisco.com/c/en/us/support/docs/dial-access/integrated-services-digital-networks-isdn-channel-associated-signaling-cas/20602-isdn-20602.html
ISDN BRI Troubleshooting Flowchart - Cisco
This document helps you to troubleshoot ISDN Basic Rate Interface (BRI) dialup access. In the flowchart and sample output shown below, we have set up
troubleshooting flowchartisdnbricisco