Call over flow question ..

Unanswered Question
Feb 2nd, 2009

I am running CM 6.1 and created a location which allow 2 G729 calls (2*24K=48K) on a H323 Gateway Gateway-A. I created a route list which has 2 route groups RG-A and RG-B. RG-A has Gateway-A and RG-B has Gateway-B. Problem I am experiencing is when I place 2 G729 calls , calls does not overflow to the RG-B/Gateway-B. Can some one see any issues with my configuration ??

I have this problem too.
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kelvin.blair Mon, 02/02/2009 - 07:15

You might want to take a look at these parameters:

1.) Stop routing on out of bandwidth

2.) Stop routing on user busy

This is located in Service Parameters-->Call Manager..

rhegde Mon, 02/02/2009 - 07:30

In my CM , service parameter for

1. Stop routing on out of Bandwitdth was set to FALSE. I changed it to TRUE hoping that after 2 G729 calls , it would over flow to the next Route Group/Gateway listed in Route list.. It did not happen. On my IP phone I get not enough BW message, while I place the call..

kelvin.blair Mon, 02/02/2009 - 07:57

Stop routing on out of bandwidth needs to be set to false. Make sure your AAR CSS is correct for calling the TEHO numbers.

Take a look at this..

Automated Alternate Routing (AAR) Limitation with Remote Gateways


AAR exhibits the limitation that calls routed over a remote gateway during a high-bandwidth situation fail, and the calls cannot be routed over the local gateway when AAR is used. This functionality is important to customers who use Tail-End Hop Off (TEHO) for toll bypass.

Recommended Action

The following example provides a workaround to use for calls that must be routed over a remote gateway in high-bandwidth situations when AAR is in use.

Workaround Example

Use a specific partition for the TEHO in question.

In the following example, headquarters (HQ) has area code 408 and the Branch (BR1) has area code 919.

Configure as follows:

1. Create theTehoBr1forHQPt partition and assign this partition to the calling search space (CSS) of the HQ devices with a higher priority than the regular PSTN access uses.

2. Create the TehoBr1forHQRL route list and add the BR1 gateway route group to this route list as the first option and the HQ gateway as the second option.

3. Apply called party modification within the route list. In this case, apply predot called party modification for the BR1 route group, and apply predot and prefix 1919 called party modification for the HQ route group.

4. Ensure that the gateway does not perform called party modification.

5. Create a route pattern in the TehoBr1forHQPt partition.

6. Ensure that no called party modifications are applied in the route pattern.


In an out-of-bandwidth situation, after Cisco Unified Communications Manager tries to allocate the first route group for TEHO (BR1 route group), Cisco Unified CM retries the second route group, at which point the system strips the 91919 string and replaces it with the 1919 string, which is suitable for long-distance dialing. Because the string is configured for use by the local gateway, less rerouting takes place.

AAR works on a per-external-phone-number-mask basis and cannot be processed for an external PSTN number because the system does not know the phone number mask of the PSTN number. This workaround provides AAR functionality and improves network resiliency.

rhegde Mon, 02/02/2009 - 08:04

Thanks for the answer, I will test it during the off peak hours and let you know..


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