Experiencing intermittent fast/busy tone when dialing out UC560

Unanswered Question
Apr 14th, 2010

We just recently rolled out a UC560 with CME 8.0/CUE 7.1.3/IOS 15.0(1)XA Release fc2.  We have 48 users with combination of 7942 and 7962 phones.  At present, we are experiencing intermittent fast/busy tone when dialing out and it happens only very small percentage of the time.  However, the user can complete the same call by simply hitting the redial subsequently after it fails.  We only have a PRI for all incoming and outgoing calls.  Attached below is partial current configuration file.  Any help or recommendation would be highly appreciated. Thanks!

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David Trad Wed, 04/14/2010 - 18:44

Hi Princeh,

What is really needed is a debug of when the bad call happens, can you do the following please:

ROTUER# debug isdn q931

ROUTER# term mon

Please capture a mad call, so you may need to repeat this proceedure more then once.

Are you certain that you have enouch channells/circuits available at the time of the call? I know it may be a silly questions, but sometimes people are unaware that they are maxing out their channel capabilities.

Cheers,

David.

princeh@princec... Thu, 04/15/2010 - 06:17

David,

Thanks for your response. The debug is attached. It appears that the call that gives fast/busy never shows up on q931 debug. Please see the call to the number ending with 3333 completed at 3:02 PM and it showed up on the attached debut but the user claimed the first attempt to the same number failed at 2:59 and she got fast/busy signal. Both attempts shows on her placed call record on the phone.

There are 16 channels provisioned for the current configuration, and we think this is more than adequate based on the call volumes we see, however, should there be any errors displayed on the q931 debug if there were no additional idle channels available to make calls or what is the best way to identify this issue?

Again, thanks!

Attachment: 
David Trad Fri, 04/16/2010 - 05:43

Hi Princeh,

Please see the call to the number ending with 3333 completed at 3:02 PM
and it showed up on the attached debut but the user claimed the first
attempt to the same number failed at 2:59 and she got fast/busy signal.
Both attempts shows on her placed call record on the phone.

Clearly there is something wrong then, because your debug shows no call attempts between the following times:

2010-04-13 14:56:45

2010-04-13 15:01:09

Well certainly nothing over the PRI during that period, so there is for sure something wrong when the user is attempting to make a call and I am wondering if it is internal, or if indeed the system is running out of channels, however if that was the case then I would have seen something in the debug.

Can you identify the following for me (sorry if this is a pain, but it is a fault finding exercise).

  • Is it just one particular user experiencing this issue? Or is it multiple users?
  • Are there other users not coming across this problem at all?
  • Is it happening on the 7962's more so then the 7942's?
  • Can you do the following at random times and inspect the amount of concurrent calls on the system, in particular just after a user complains

    ROUTER# sh voice call sum

  • what are the current phone loads?

    ROUTER# sh ephone phone

  • Are you willing to provide a running configuration to inspect the config? (Passwords and other sensitive information removed please)

I am curious about this problem and determined to help you with it, however I have learnt one important thing, if fault finding an issues takes far to long to resolve using normal methods, you log a support case in before it drags on, however I notice you are running a 560 which is Small Business Support, and I am not sure how effective support will be, the amount of complaints I am getting from industry colleagues and also noting the ones here on the forums, you might find the process a little daunting until they find a better method of supporting these newer appliances.

What time zone are you in? If there is a workable time I would be happy to SSH into the device and run some debugs with you, or we can arrange for a remote desktop session (Using Team Viewer) and we can do it of your system, sorry no webex as the company I work for wont pay the money they want for it, and I personaly don't want to either, I dont get paid enough for that LOL :D.

I think you need to be careful that this problem does not lead to other things, or become a bigger problem, if you can arrest it now it might save you a world of hurt. I have learnt over time the quicker you resolve the problem, the less chance it will resurface.

Cheers,


David.

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