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Troubleshooting
Symptom
Two devices cannot ping each other over an ISDN PRI or BRI line.
Analysis
The following are typical ISDN call failure causes:
• The ISDN interface is not configured or activated.
• The dial-up configuration is incorrect.
• The line is not well connected.
Solution
To resolve the problem:
1. Execute the display isdn call-info command to verify the interface settings:
a. If the command displays nothing, configure an ISDN interface. For more information about
configuring BRI, CE1/PRI, and CT1/PRI interfaces, see Interface Configuration Guide.
b. Verify the Q.921 state of the PRI or BRI interface:
− If the PRI interface's link layer 1 is not in ISDN MULTIPLE_FRAME_ESTABLISHED state,
Q.921 negotiation has failed. You must check Q.921 settings or the physical connection.
− If any link layers of the BRI interface are not in TE1_ASSIGNED state, Q.921 negotiation has
failed. You must check Q.921 settings or the physical connection.
− If the Q.921 state is correct, verify the dialup configuration.
2. Verify that the physical layer is active:
a. Enable Q.921 debugging.
b. If the system displays a "Failed to send" message, execute the shutdown and undo shutdown
command to re-enable the interface.
3. Verify that the dial-up configuration is correct.
4. Verify that the ISDN cables are securely connected.
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