System information

Troubleshooting ISDN Connections 17-381
ISDN: Dial Does Not Go Through BRI
Number in use Step 1 Turn on ISDN debugging using the following privileged exec
commands:
C4000#debug isdn event
ISDN events debugging is on
C4000#debug isdn q931
ISDN Q931 packets debugging is on
Caution: Because debugging output is assigned high priority in the
CPU process, it can render the system unusable. For this reason, use
debug commands only to troubleshoot specific problems or during
troubleshooting sessions with Cisco technical support staff.
Moreover, it is best to use debug commands during periods of lower
network traffic and fewer users. Debugging during these periods
decreases the likelihood that increased debug command processing
overhead will affect system use.
Step 2 If the debug output says “User busy,” the remote ISDN number is
probably in use.
Misconfigured SPIDs
1
Step 1 Use the show running-config privileged exec command to view the
router configuration. Look for an isdn spid1 spid-number interface
configuration command entry.
Step 2 Verify that the SPID specified in the command is that assigned to
you by your service provider. Use the set spid command to enter the
correct spid:
set spid
set [spid id] spid [spid number]
Syntax Description:
• spid id—(Optional if there is only one SPID) Used as a convenient
single-digit number to identify the actual long SPIDs allocated by
service providers.
• spid number—Number identifying the service to which you have
subscribed. This value is assigned by the ISDN service provider
and is usually a 10-digit telephone number with some extra digits.
The SPID number can consist of 1 to 20 digits.
Misconfigured SPID Examples:
The following example sets two SPIDs for the line:
Host> set 1 spid 0408555123401
Host> set 2 spid 0405555123402
The following example deletes the first SPID:
Host> set 1 spid
Incorrect cable Step 1 Make sure you use a straight-through RJ-45 cable. To check the
cable, hold the RJ-45 cable ends side by side. If the pins are in the
same order, the cable is straight-through. If the order of the pins is
reversed, the cable is rolled.
Step 2 If you are using a rolled cable, replace it with a straight-through
cable.
Possible Problem Solution