All circuits busy

Unanswered Question
May 31st, 2007

We have a 3825 with two PRI's terminated on it, that is the voice gateway to the PSTN for about 50 clients (200+ phones). They use varying systems including routers with FXS cards (and analog phones), CME, and SIP voice. Ocationally when someone is trying to call a customer they get a message "all circuits buys" Then they try again a few times and the call goes through.

Are there any logs I can setup on my gateway to determine if we are maxing out on channels at times, which would give this message to the people calling in?

Any thing eles I can check to determine if this issue is mine or the Telco's?

I have this problem too.
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jmccartney1 Thu, 05/31/2007 - 11:49

I would try to setup debug isdn q931 and see if the incoming call tries to go from channel1 to channelX. If so you may have a carrier issue, I've seen this before.


davecisco Thu, 05/31/2007 - 15:55

The only issue I have with this is that debug is rather CPU intensive, and I do not know when this is going to happen. It only happens intermittently.

One thing I did not mention is that these PRI's are supplied buy the telco in one city and we back-haul them over a T1 to our hub. Could that be related to what you are mentioning about the carrier issues?

Paolo Bevilacqua Thu, 05/31/2007 - 17:42


Debug Q.931 is not that intensive and can be enabled in total safety with two T1. As with all debugs, you may want to disable logging to console, and only log to buffer.

You may want to do some "show isdn status" at peak time to verify you channels usage. There is also a MIB that you can poll but I don't remember now which one it is.

Hope this helps, please rate post if it does!

davecisco Thu, 05/31/2007 - 17:45

Thanks for the help.

If I do the "sh isdn stat" what indicators should I be looking for?


Paolo Bevilacqua Thu, 05/31/2007 - 20:03

Look for number of active calls.

As a courtesy to those providing answers, please rate all useful posts!

davecisco Fri, 06/01/2007 - 07:51

I have the debug running to a syslog server now. What should I be looking for for errors?


davecisco Fri, 06/01/2007 - 08:28

Here is a syslog message that I get when I do a debug isdn error interface ser 1/1:23

7-06-01 10:25:20 Local7.Debug 64084: Jun 1 16:25:20.572: ISDN Se1/1:23 **ERROR**: call_cleared: VOICE ERROR: Bearer capability not available(0x3A): bchan -1, call id 0xBA5F

2007-06-01 10:25:20 Local7.Debug 64085: Jun 1 16:25:20.768: ISDN Se1/1:23 **ERROR**: CCPMSG_OutCall: fails with cause 0x22

2007-06-01 10:25:20 Local7.Debug 64086: Jun 1 16:25:20.768: ISDN Se1/1:23 SERROR: call_cleared: Got a disconnect on a non-existent call (call id = 0xBA61).

2007-06-01 10:25:20 Local7.Debug 64087: <009>This probably is a call that we placed that failed.

Any ideas?

davecisco Fri, 06/01/2007 - 07:52

I have the debug running to a syslog server now. What should I be looking for for errors?


Paolo Bevilacqua Fri, 06/01/2007 - 12:23


Do you have someone on your CCME using VT advantage ?

Please configure under your T1 voice ports:

bearer-cap Speech

Hope this helps, please rate post if it does!


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