[cisco-voip] FXO Disconnect Detection

Wed Sep 21 19:21:36 EDT 2016

I don't know much about U.S. standards but I'd be surprised if it was required. It would probably just depend on your contract with them. I.e., if they have a written technical specification of the service you are buying, then obviously they need to meet that specification. In Canada, those specifications are typically in or referenced by the "tariff" that the telco files with the federal regulator and can be found online.

You mentioned that the telco "eventually" plays a tone and an operator announcement. Obviously immediate detection would be preferred, but eventually is at least better than never. You should be able to configure "supervisory disconnect dualtone mid-call" on the voice-port to hangup when it hears the tone. Depending on what the tone is, you might have to configure a "custom-cptone" so that the voice-port knows what to listen for.

I have a site in a remote rural hamlet that gets its phone lines from a CO in another town via an ancient analog multiplexer. Telco tried to get linecards for it that support disconnect signaling; they exist but are too ancient to find. So I'm stuck using the "eventual" tone at that site. Better than nothing.

-mn

-----Original Message-----
From: cisco-voip [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Hughes, Scott GRE-MG
Sent: September-21-16 3:18 PM
To: Esmaeel Saberi <esmaeels at gmail.com>
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] FXO Disconnect Detection

Thanks for all the advice. An update on this issue:

We have been in contact with the carrier. They have indicated that others have had similar issues, all since moving to a “new” softswitch at the CO. The CO tech has apparently verified that the signalling is going out, but doesn’t get passed through the DSLAM that is somewhere in between the CO and our premise.

Is there anyone who is knowledgeable about telephone standards & regulations? Is the carrier REQUIRED to do disconnect supervision, or is it merely a courtesy?

On Sep 12, 2016, at 1:11 AM, Esmaeel Saberi <esmaeels at gmail.com<mailto:esmaeels at gmail.com>> wrote:

EXTERNAL

This link is usefull 😉
https://supportforums.cisco.com/discussion/11127921/fxo-4-voice-ports-always-busy
On Mon, Sep 12, 2016 at 10:34 AM Esmaeel Saberi <esmaeels at gmail.com<mailto:esmaeels at gmail.com>> wrote:
Hello
You must record the sound of busy or congestion tone and define the frequency in router

On Mon, Sep 12, 2016 at 5:21 AM Sreekanth <sknth.n at gmail.com<mailto:sknth.n at gmail.com>> wrote:
Hi Scott,

When reaching out to the telco, ask them what kind of disconnect they're doing. Is it:
1. Battery reversal
2. Power denial
3. Supervisory disconnect - tone played by the telco to indicate a disconnect

You've mentioned that when the remote party disconnects, the VoIP phone stays off hook. Do you hear a disconnect tone during this period? If so, the telco is using supervisory disconnect.
In that case, your DSPs on the router may need a tweak. You can do 2 things:

1. Take pcm captures on the router to capture the disconnect tone. Then open a case with TAC who can decode this and give you the settings for the supervisory disconnect.
2. Do the ds0-dump on the router and capture the tones, decode them yourself using Audacity and put in the settings.

DS0-dump: http://www.cisco.com/c/en/us/support/docs/voice-unified-communications/unified-communications-system/115749-analyze-pcm-data.html

Video for setting up pcm captures and Ds0-dump.
https://www.youtube.com/watch?v=HkPjTBvx_YA

Cheers!

On 12 September 2016 at 05:30, Ryan Huff <ryanhuff at outlook.com<mailto:ryanhuff at outlook.com>> wrote:

Scott,

You are correct, it is the default. Oddly, what I meant to suggest is that you try disabling (no battery-reversal) but it seems that I suggested you to enable it (in which it has always been enabled). Try disabling the support and see what happens.

Apologies!

Thanks,

Ryan

________________________________
From: Hughes, Scott GRE-MG <SHughes at GREnergy.com<mailto:SHughes at GREnergy.com>>
Sent: Sunday, September 11, 2016 7:13 PM
To: Ryan Huff
Cc: cisco-voip at puck.nether.net<mailto:cisco-voip at puck.nether.net>
Subject: Re: [cisco-voip] FXO Disconnect Detection

:-/ unfortunately, that command must already be a default is IOS 15.5M because it doesn't show up in the running config after I put it in.

Thanks for the suggestion though!

On Sep 9, 2016, at 6:21 PM, Ryan Huff <ryanhuff at outlook.com<mailto:ryanhuff at outlook.com><mailto:ryanhuff at outlook.com<mailto:ryanhuff at outlook.com>>> wrote:

EXTERNAL

You may try enabling support for battery reversal detection on the voice port;

voice-port x/x/x
battery-reversal
!

-Ryan

On Sep 9, 2016, at 6:57 PM, Hughes, Scott GRE-MG <SHughes at GREnergy.com<mailto:SHughes at GREnergy.com><mailto:SHughes at GREnergy.com<mailto:SHughes at GREnergy.com>>> wrote:

Hi,

I have a Cisco 2921 H.323 gateway tied to CUCM 11 with 4 FXO (loop start) ports in a trunk group. Unanswered calls get forwarded to an offsite answering service (hairpinning out of the same set of FXO ports). Ports are setup with "connection plar opx 1000"

My issue is that ports don't detect when the other end hangs up. When a remote party hangs up, the VoIP phone stays off hook and eventually plays a dial tone, followed by an operator message.

I suspect that the forwarded calls terminate but both FXO ports in the hairpin stay off hook indefinitely.

How can I combat this problem? I can reach out to the telco but need to know what to ask for.

I am located in the US, if that makes a difference. I've read many articles about supervisory disconnection but none really help with troubleshooting steps or timers to tweak.

-Scott

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