System information

Troubleshooting ISDN Connections 17-383
ISDN: Dial Does Not Go Through PRI
ISDN: Dial Does Not Go Through PRI
Symptom: ISDN router using a PRI port successfully dials, but the call does not go through.
Table 17-3 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 17-3 ISDN: Dial Does Not Go Through PRI
Possible Problem Solution
Speed setting mismatch
Step 1 Use the show running-config privileged exec command to view the
router configuration. Check the dialer map interface configuration
command entries in the local and remote router. These entries should
look similar to the following:
dialer map ip 131.108.2.5 speed 56 name C4000
Step 2
Compare the speed setting configured on the router interfaces to the
speed of your ISDN service. The speeds must be the same. To set the
speed on the router, use the speed 56 | 64 keyword in the dialer map
command.
Note: If the speed is not explicitly specified, the dialer map defaults
to 64 kbps.
Step 3 If you do not know the speed of your ISDN service, contact your
ISDN provider. Long-distance calls are usually 56 kbps.
For detailed information on configuring dialer maps, refer to the Cisco IOS
Wide-Area Networking Configuration Guide and Wide-Area Networking
Command Reference.
Misconfigured dialer map
Step 1 Use the show running-config privileged exec command to view the
router configuration. Look for dialer map interface configuration
command entries.
Step 2 Make sure that each dialer map contains the phone number of the
remote PRI.
Step 3 If the phone number of the remote PRI is properly specified in each
dialer map statement but the dial does not go through, the first call
failed and there are no numbers left to try.
Step 4 Make sure a phone number is configured, and then clear the interface
using the clear interface privileged exec command and try dialing
again.
For detailed information on configuring dialer maps, refer to the Cisco IOS
Wide-Area Networking Configuration Guide and Wide-Area Networking
Command Reference.
Number in use
Step 1 Turn on ISDN debugging by using the debug isdn events privileged
exec command.
Step 2 If the debug output says “User busy,” the remote ISDN number is
probably in use.