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FXO Disconnect issue

I have got a 2811 router with 4 FXO ports ( loop start )configured a h.323 gateway with ccm 4.0

The FXO port shows connected even after the far end party hang up the call , I have tried various commands in router to provide the supervisory disconnect , but still having the same issue,

Any help will be appreciated.


Re: FXO Disconnect issue

We have samilar problem before, it fixed after put command "no battery-reversal" under voice-port.




Re: FXO Disconnect issue

ive had countless issues with repect to this, and this seems to cause a lot of instability for the overall system. the disconnection parameters work but still doesnt disconnect immediately. they normally take about 10-20 sec to disconnect for me,

if youve tried all the basic troubleshooting you can also try what i did.

1. Call your carrier, and advise that you want to put your PSTN lines as a trunk, and as well enable COD on thier end.

2. do the normal call disconnect commands as well

3. Most sites worked fine and disconnected immediately after this but i had two sites that were still having issues. i downloaded cisco IOS software 12.3 (14T) voice to get the command sup-disconnect. this is under the timing parameter. enable the same timing that the carrier has, in my case it was 300ms.

4. finally, i created voice classes and specified detection parameters. i used a software to analyse the frequencies for each of the tones.

i know its a lot, and my entire project was going downhill becuase all my sites were having this issue. these are the steps i took to resolve the issues. System has been up for approximately 2 years now and we are have no issues with this. im not sure if this may help in your case but i hope that it may be of some assistance.

PS. if you have a pilot number (Carrier side) tied into other PSTN lines, the first line still remains off-hook intermittently. i have noticed this with another implementation

New Member

Re: FXO Disconnect issue


The COD (Cutoff on Demand) has fixed this issue on several customer installs of mine. The biggest complaint was "ghost" calls when incoming calls played an opening greeting, then when the caller hung up, the router and CCM still processed the calls through which ended up at the receptionist and nobody was there, obviously since they hung up. Once we called the telco and had them add the COD codes to the lines, the issue went away. We verified this by doing a show call active voice and saw the calls correctly drop when the caller hung up. We never had to mess with any of the disconnect commands.



Re: FXO Disconnect issue

Here is a document explaining this issue.

We use ground start which works great, is simple to configure, and can be ordered from most carriers.

Please rate helpful posts.


Re: FXO Disconnect issue

how could i forget to mention that,

by all accounts ground start is supposed to fix all those issues, im probably the only one that had issues with this, hence my work-around. i initially had the sites with GS and they worked fine, after a couple of days however, customers calling in got a busy tone. i checked a couple of this but resorted to my initial setup which was proven for me.

Not even too sure if GS was the issue but as soon as i reverted to LS everything worked.

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