FXO port not getting disconnected.

Unanswered Question
Mar 6th, 2008

Hi Here is my scenario..


Router : 2811

Port : VIC2-2FXO

IOS: 12.4(17)

If I make calls from one ph to another the fxo port is not getting disconnected after I hangs up the phone.

I tried battery reversal, supervicory disconnect combinations ...Please advice...



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Overall Rating: 0 (3 ratings)
Paolo Bevilacqua Thu, 03/06/2008 - 00:50

Do you receive a tone when remote disconnects ?

If so you can do tone base disconnect.

Beside that, if the application is between telephones staffed by persons, both will hang up, so no problem.

manoj.kv Thu, 03/06/2008 - 01:28

Yes. Iam gettign a disconnect tone....but even after both phones hangs up, Fxo port remains active... Can't make another call through that port. Please advice..

Thanks in advance..


manoj.kv Thu, 03/06/2008 - 02:09


Thanks for the reply... I tried all thease combinations, But not working....please advice...


thomasarun Thu, 03/06/2008 - 08:06

Manoj who is your service provider?

and how u found that u r getting disconnect tone...?

manoj.kv Thu, 03/06/2008 - 18:13

Its a PBX to pbx connectivity for internal communication..Captured the tone using wireshark...

Paolo Bevilacqua Fri, 03/07/2008 - 01:46

Please understand that the design itself is wrong to begin with.

Basically you're trying to build a trunk between two pbx, using the extensions port of them.

But if you ask the pbx company to trunk two pbx, they will tell you that is not possible to do that using the extensions, and you have to purchase some kind of trunking interface.

And they are right, you cannot do a good work using fxo interfaces. Please use isdn bri, E&M, or as extreme resort, a mix of fxs / fxo. You will receive the call into fxs, send it out to fxo.

Anyway, if you want to insist using fxo/fxo, have wireshark produce an audio file, or record again, post it here, together with the tone disconnection configuration you're using,

manoj.kv Tue, 03/18/2008 - 10:47

Thanks for the reply, Could you please tell me how can I create an audio file using wireshark, I tried, but its giving a weird output.

ALso could you please tell me how can I use mix of fxs/fxo ? ( There is a CO Port in PBX)



Paolo Bevilacqua Tue, 03/18/2008 - 11:05

If you search for wireshark with the form on the right side, there is a previous thread where the procedures are given. If that is too complicated, just record with a PC and microphone.

When you connect fxs/fxo, you configure so that the pbx make calls into router fxs port, while router make calls into pbx fxs port. it is only a matter of configuring the DP and nothing else.

Paolo Bevilacqua Tue, 03/18/2008 - 11:56

Where are you located? It seems to be 460 Hz, not sure if secondary frequency is present, 375 ms on, 375 ms off.

If would be better if you get the fxs card as in many cases trying tone-based disconnect supervision doesn't work.

manoj.kv Tue, 03/18/2008 - 12:10

Thanks for the reply, I'm from India, Could you please send me any link to get an idea on how to use fxs card in this type of scenario ?



Paolo Bevilacqua Tue, 03/18/2008 - 12:59

Ok, you PBX does not use the same disconnect tone like telco in India.

To use fxs port, connect to the fxo port in pbx, that you call co port. Configure PBX so that when a certain prefix digit is called, this port will be used. Router will receive the call and route to remote router, remote router will place call out of fxo port to pbx, single stage dialing, it's very simple actually.


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