H323 GW - Maxing PRI lines

[Ayaz Khan]

Hello,

Wondering if there is anything I could do to determine if I am maxing out my PRI lines.

The issue we are facing is;  Intermitintly calls are going out a FX0 port before using the PRI.  Client is certian that PRIs are not maxing out.  Dial-peers are configured with preference so if the lines are not maxed out, FX0 ports should never be used.

Looking for a command or a threshold I could set to alert me that Maximum lines have been used.

IOS version is  Version 15.1(4)M4

Thanks,

AK

[Manish Gogna]

Hi Ayaz,

Since this is an H323 gateway, the CUCM does not have control over the PRI's. You can remove the FXO ports from the dial-peer hunt for test purpose, just leave the PRI's for call routing. Create a Route List on CUCM with First route group as the H323 gateway in question , and add another route group in the same route list as a backup through some other gateway or trunk. In case the first H323 gateway is maxed out for PRI b channels , you will get a RTMT RouteListExhausted RTMT alert as explained here

    [RTMT-ALERT-StandAloneCluster] RouteListExhausted
    Explanation: An available route could not be found in the indicated route list

Solution

The RouteListExhausted messages indicate that CallManager was unable to send a call to those Route Groups in a Route List. This is usually as a result of no B channels or ports being available on a gateway for routing a call. 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, then sometimes the first H.323 gateway will send a User Busy back to the 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 own Route List is configured, then go to Cisco CallManager Administration > Service > Service Parameters > Select a server > Select Cisco CallManager and configure the Stop Routing on User Busy Flag service parameter to False.

This will mean that the CallManager will try other gateways to re-route the call on a User Busy before reaching the RouteListExhausted state. However, if there are no RouteListExhausted events in the Application Log, then the RouteListExhausted messages reported by RTMT can be a result of an Unallocated number or User Busy messages from the PSTN. In this case, this message can be ignored.

http://www.cisco.com/c/en/us/support/docs/voice-unified-communications/unified-communications-manager-callmanager/109377-rtmt-error-tshoot.html#p4

This will at least let you know if the PRI's are maxing out or not.

You can also run use the command "show call active voice" during peak hours to get an idea of the call volume.

There are other options available like generating CDR files from the gateway itself as explained here

http://www.cisco.com/c/en/us/support/docs/voice/h323/14068-cdr-logging.html

HTH

Manish