This document looks at some situations in which long distance Basic
Rate Interface (BRI) calls fail, but local calls are successful. In such cases,
the call does not even reach the remote router and the connection is terminated
somewhere within the Public Switched Telephone Network (PSTN) cloud.
Note: This document does not address issues where even local calls fail.
For troubleshooting general BRI issues refer to the document
This document makes the following assumptions:
The BRI circuits on both routers are provisioned and functioning.
The ISDN number used to dial the peer is known.
Only outgoing long distance calls fail. If local calls fail as well,
refer to the document
Users must be able to read and interpret debug ISDN
q931 command output and Q.931 disconnect cause codes.
For more information on reading debug ISDN
q931 command output, refer to the document
ISDN BRI Layer 3 using the debug ISDN q931
The information in this document is based on these software and
The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.
For more information on document conventions, refer to the
Cisco Technical Tips
Some common causes for long distance calls failing are as follows:
Provisioning issues at the local Telco. In such cases, the local
Telco may not have specified the long distance carrier to be used.
Problems within the long distance provider.
Problems with the local provider's interface to the long distance
provider. However, this is a rare issue.
The following conditions are symptomatic of long distance
For more information on reading Q.931 disconnect cause codes, refer to
debug ISDN q931 Disconnect Cause Codes.
Note: The above listings are the most commonly seen and may not
occasionally represent the actual code generated by the Telco.
The procedure to resolve this issue involves the following three
Generate an ISDN layer 3 call without using Dial-on-Demand Routing
(DDR). This can help isolate and eliminate router configuration issues as the
cause of the problem. Use the
call interface command
, introduced in Cisco IOS software
12.0(3)T, to initiate the call.
If the call succeeds, then the ISDN network (and long distance
provider) are not to blame and the issue is likely a configuration problem.
Re-check your DDR configuration.
If the call fails, continue to the next step.
Generate a loopback call to verify that the BRI circuit to the
Telco switch is functioning. You should perform an ISDN loopback call as well
as the data loopback call. Refer to the document
Loopback Calls to Test BRI Circuits for more information on this
Note: If you are able to make local calls on the circuit in question,
then this step can be omitted
Use an alternative long distance provider.
Customers in North America can use a Presubscribed Interexchange
Carrier (PIC) code to specify a long distance provider on a per-call basis. PIC
codes are seven-digit prefixes which identify North American long distance
carriers to the local exchange carriers (LEC). This allows customers to use
different long-distance carriers for separate calls. The PIC code is configured
as a prefix to the dialed number. Most PICs are of the format 1010xxx.
To configure a PIC, first remove the old dialer string or dialer
map (using the no dialer string or no
dialer map command) and configure the new one with the 1010xxx
code, followed by 1, then the area code and number to be dialed. For example:
maui-soho-01(config-if)#dialer string 101033315125551234
Note: A PIC code is a workaround for long distance call failures. For
a proper resolution to this issue, you should contact your Telco to have the
long distance provider correctly designated and the call routed to that
provider. Refer to the section Questions for your Telco Provider for more
Customers in rest of the world should contact the Telco provider
to have the long distance carrier correctly designated and the call routed to
that provider. Refer to the section Questions for your Telco Provider for more
Ask the following questions of your Telco when troubleshooting long
Refer to the following site for contact information for various US
Is the long distance provider correctly specified for the circuit?
The local Telco should specify the long distance provider you
designate. If you have used a PIC code to successfully place a call, provide
that information as well. This issue is often seen during new circuit
provisioning or when the long distance carriers are changed.
Is the long distance provider correctly provisioned for this BRI
Verify that the long distance provider supports the long distance
service you requested and that the circuit is provisioned correctly.
Are the spid numbers registered by the provider?
Verify that the long distance provider has the correct spid values