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AMA-CUCM Troubleshooting: Best Practices for Reading Trace Files


Random long distance failures over PRI

I have 2 PRIs that we are getting random long distance failures on outbound calls.  These calls result in 1 ring and then a message stating "Thanks for choosing so and so for your long distance needs." and then going to fast busy before disconnecting.  When it happens, it is always saying a long distance carrier that we don't use at any of our locations(ie, we are using AT&T, and one of the numbers we called resulted in saying thanks for choosing Nextel).  This is happening across all device pools and CSS.  CDR records show the call being passed to the PRI correctly.  I called AT&T thinking this is a PRI issue, but all they did was test the circuit, say it was good, and close the ticket.  I'm not completely familiar with PRI, but is it possible that  AT&T could have different channels on the circuit set to use different long distance carriers?  My thinking now is that maybe a couple of channels are set to the wrong carrier, the call is being passed out on one of those channels, it's starting to complete the call, and the wrong carrier is finding that we don't have an account and terminating the call.  Since the same phone can sometimes call the same long distance number and be connected, after previously getting the error on that called number, it really doesn't seem to be on my end.  Anyone seen anything like this?


Have you tried to do "debug

Have you tried to do "debug ISDN Q931" on the gateway, then pull the entries that failed to see if always same channel?  Also can busy out (various method for this depending on if MGCP or H.323) various groups of channels to more easily test multiple.  Calls out typically are set to bottom up for example so testing would go best afterhours, then use multiple phones to call out.  If 4th connected caller always fails then channel has carrier issue.

Q931 will also show if anything in the PRI message is different from working calls that could potentially cause it.


Hi , this is very unlikely to

Hi , this is very unlikely to be your fault and mostly likely how your carrier is routing calls.

You need to explain to whoever you're carrier is the exact problem , give them the exact details of the calls that failed time , destination etc etc , then they should be able to trace where the call is being routed and hopefully find the fault.

Channels are not assigned to individual carriers on a PRI so you can rule that one out.They will all connect to the local carrier.

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