Problem regarding the using of B-ACD with PSTN connection

Unanswered Question
Nov 6th, 2007

Hi, recently i faced a problem regarding my PSTN connection through FXO card but it was fixed :to sum up the whole thing when i dial from the PSTN to reach my FXO card the phone start ringing on the IP PHONE but when i unhook the phone from the PSTN the IP PHONE still ringing but i sole this problem using the CMD :connection plar opx 102 under my FXO port BUT THE PROBLEM STILL THERE WHEN I'M USING THE B-ACD SCRIPT thanks for helping me out , you will find in attach o copy of my router configuration.


I have this problem too.
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Paolo Bevilacqua Tue, 11/06/2007 - 03:08


This happens because even with connection plar opx, AA-BACD immediately answers the calls, and doesn't recognize when the caller hangs-up.

So you have the classic problem of disconnect supervision as explained here:

So, either you confgiure the correct tones for your contry/.telco, or switch to ISDN BRI, that gives you many more features and never the disconnect problem.

Hope this helps, please rate post if it does!

Seifeddine-Tlili Tue, 11/06/2007 - 04:27

Damn it really makes me sick this problem, i don't even find any solutions; i read the doc that you provide me (and thx ) but still no solution to solve it the IP Phone still ringing and i know this problem is related to the FXO card cauz when i disconnect to PSTN's cable the call was released

Thanks for looking after this


Paolo Bevilacqua Tue, 11/06/2007 - 04:36

Answer the call on the IP phone, then have the call from outside hangup. Listen to the tones, and see if these matches the ones listed for your country at:

Unless you configure the correct frequencies a the custom config as mentioned in the document, disconnect will never work.

Hope this helps, please rate post if it does!

Seifeddine-Tlili Tue, 11/06/2007 - 04:44

Sorry but what did you mean by "have a call from outside hangup" is that the equivalent of listening to the tone when phones ring or what and then what tones did i have to focus in ?

thanks for your help Sir.


Paolo Bevilacqua Tue, 11/06/2007 - 04:53

Someone calls you from the PSTN. He gets the AA-BACD prompts, and then talks with you on the IP phone.

Then this person hangs up, that is, he/she puts down the handset. To all effects, he is disconnecting the call.

You on the IP phone should hear the disconnection tones. These are the tones you need to configure in the router, so that it will be able to recognize them, and disconnect as well.

Seifeddine-Tlili Tue, 11/06/2007 - 05:22

Hey thanks for your help, i cannt recognize my dial tone but at least i have understood what i'm suppose to do for in order to solve this problem but it seems like some cmd doens't work on my router i have the 2811 cisco's router with IOS 12.4T, some cmd like freq-pair under voice class aren't supported by my router.


Paolo Bevilacqua Tue, 11/06/2007 - 05:27


the commands should be supported. Note, you must recognize disconnect tone, not dial tone.

As a recognition to those providing answers, please rate useful posts!

Seifeddine-Tlili Fri, 11/30/2007 - 04:49

SO in case if i didn't find a disconnect tone with my supervisor (cauz our telephony provider doesn't provicde information related to the disconnect tone) so is there any solution except the one related to define a custom cptone.

thx in advance

Paolo Bevilacqua Fri, 11/30/2007 - 05:41

There is no other solution beside listening or recording the disconnect tone and configure it.

Most likely, it will be the same as used in some other country.


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