Core Issue
This issue can occur if an available route is not found in the indicated route list.
If the call fails on the current gateway, Cisco CallManager attempts to extend the call to the next route in the route list. This occurs until it reaches the last route. If the call cannot be completed with the last gateway, the Route List Exhausted event is logged.
These are possible reasons for a failure on the current gateway:
The user receives alerts similar to this in the Real-Time Monitoring Tool (RTMT):
Most Recent Alert Raised: At 09:19:27 on 12/21/2005 on cluster CALLMANAGER1-Cluster. Number of RouteListExhausted events exceed 0 within 60 minutes.
There are at least five RouteListExhausted events (up to 30) received during the monitoring interval from 09:07:27, 12/21/2005 to 10:07:27, 12/21/2005.
Resolution
The Route list Exhausted event can usually be ignored. For example, the Unallocated Number error message may be received if the user calls a non-existing destination or if a destination is busy. In this case, the destination is busy when it tries the next available gateways.
This usually occurs because there are no B-channels or ports available on a gateway for routing a call.
For more information, refer to System Error Messages for Cisco CallManager 4.0.
Note: Only one gateway should be configured per route group.
If you have a route list with an H.323 gateway as the first route group, and a second route group that should take any overflow, the first H.323 gateway sometimes sends a user busy back to the Cisco CallManager if all of its channels or ports are busy. If this occurs, then the call is not forwarded to the second route group in the route list.
If this is how your route list is configured, set both the Stop Routing on User Busy Flag and Stop Routing on Unallocated Number Flag service parameters to False. In order to do this select Cisco CallManager Admin > Service > Service Parameters > Select a Server > Cisco CallManager.
The Cisco CallManager tries other gateways to re-route the call on a user busy prior to reaching the RouteListExhausted state.
There have been instances where the first H.323 gateway returns the Unallocated Number to the CallManager message when the controller has been shut down.
Alternatively, the site could simply be running out of channels or ports to access the Public Switched Telephone Network (PSTN). If you have no H.323 gateways, you have likely run out of B-channels or ports.
If you never see high utilization, you want to look at any possible call forwarding loops (For example, someone forwards a work phone to their cell phone, and they have their cell phone forwarded back to their work phone). This can cause all the B-channels to be utilized very briefly. This situation results in the RouteListExhausted event and a fast busy for the caller being forwarded in circles.
When the gateway fails to respond to the call setup request, perform these steps:
- Find out if the gateway was registered to Cisco CallManager at the time of the call.
- If this event is not caused by similar failures, enable the detailed Cisco CallManager traces with the procedures outlined in Set Up Cisco CallManager Traces for Cisco Technical Support.
- Also, analyze the call setup and disconnection sequences with the Q.931Translator.exe located in C:\Program Files\Cisco\bin.
- Additional routes may be needed in the indicated route list.
Another way to avoid this error is to set the value for the Stop Routing on Unallocated Number Flag* Service parameter to TRUE on all nodes in the cluster.
For more information on this issue, refer to CallManager Event Logs.
