CUE 2.3.4 issue with FXO ports staying connected

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Jul 15th, 2007
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I am running into a problem with one of my sites. People place calls into our main number and the AA answers. I have noticed if someone hangs up while it is playing it will leave the FXO port connected for several mins. I verified this by placing a call into the main number and then disconnecting. On the router i issued a sh voice call sum and port 0/0/2 is still open several mins after I disconnected. Now if I place another call it rolls over to the other line we have and the same issue happens. At that point I can no long call into the system. After it times out or disconnects(Not sure) it works fine.


Now I know with IPCC i can do an on exception cisco contact disconnect and send it to end. If this the same issue I am running into and if so how do i correct it.


Cue 2.3.4


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paolo bevilacqua Sun, 07/15/2007 - 16:59
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This is the FXO disconnect problem, see:

http://www.cisco.com/en/US/tech/tk652/tk653/technologies_tech_note09186a00800ae2d1.shtml


In addition to the document, note the following:


1. converting to ISDN BRI will definitely fix and will give you the advantages of ISDN.

2. If you are noth in north america, or telco can't supply "ground start lines", this method is unapplicable, so you have to configure for disconnect tones.

D0nprintup_2 Mon, 07/16/2007 - 05:04
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I am in north america and its a normal POTS line connected to the FXO ports. The lines used to have 4 analog phones untill we got this router.

paolo bevilacqua Mon, 07/16/2007 - 06:21
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Ask telco to convert lines to 'ground start'. It is easy and reliable. If they can't or won't, you will have to configure supervisory disconnect tones.

D0nprintup_2 Mon, 07/16/2007 - 06:28
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ok cool, now if I have to convert over to disconnect tones. DO i need to involve the the telco.


See I have the same setup in a different state and it works fine. Same config (Well I changed the ip's and stuff) but basicly the same setup.


4 analog lines with which hunt from one to the other. And the config is almost identical.


I dont understand why it doesnt work here. On the one that works I do not have anything configured in the voice-port .... only a plar statement and when you disconnect remotely on that router within a few secs you can see fx_gaurdout and the port clears.


Could the Telco in the other state be sending tones to disco the call? If so could this mean the telco at the location that isnt working. Is not sending tones?


paolo bevilacqua Mon, 07/16/2007 - 06:47
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For tones-based disconnect, you don't need anything on the telco side.


If you think about, when the caller is in AA or any other automated call handling, there is nothing beside tones or line signaling to tell the router that caller has hang up.


If you collect "debug vpm signal" on your various installation, you would see that where "it works", there is something like a power denial, battery reversal, etc, that is causing the router to hang-up without long timeouts.


D0nprintup_2 Mon, 07/16/2007 - 06:54
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ok

after a debug on the one that works I see 350ms timer which would say power_denial. The next line in the debug shows FXOLS_POWER_DENIAL and it triggers the release.


On the router that isnt working, as you noted I do not see anything once I disconnect.


So this means the telco isnt sending a sup disconnect to us?


I am not 100% with this kind of stuff, for Power Denial-based Supervisory Disconnect


is that something I can call teh telco and say I need this on the lines?

paolo bevilacqua Mon, 07/16/2007 - 07:01
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Yes I believe so. As networkers we like to think that with the same basis you get the same results.

D0nprintup_2 Mon, 07/16/2007 - 07:09
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Ok Power Denial-based Supervisory Disconnect is how the one thats working.


I can call the telco and ask them to send that on the ones not working?

paolo bevilacqua Mon, 07/16/2007 - 07:16
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Sure. Hope you can find someone that understand what you need, because at times telco's people apparently do not know how their very product works.

Then again sometime problems are real depending on the switch you are connected to, any equipment that may be in the loop, etc.

D0nprintup_2 Mon, 07/16/2007 - 07:30
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At times I dont understand how my products work :(. But I am learning and trying.


I read the data sheet and it says the default settings is sup disc signal and thats the power disconnect.


With the debug I do not see that so it would lead me to believe that its not being sent or there is a "Cisco Bug".


I will attempt to work with the telco first.


paolo bevilacqua Mon, 07/16/2007 - 07:49
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Worry not, if you don't see it, it is not being sent.

Sometime talking to telco you have to say things in a simplistic manner like "please make the line for a PBX". They go and configure things from a template and you have it working.


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D0nprintup_2 Mon, 07/16/2007 - 07:54
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THank you for all the information you have given me. I have learned alot

paolo bevilacqua Mon, 07/16/2007 - 08:50
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Thank you for the nice rating and good luck!

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