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Disconnect problems on FXO port

We have some problems with the call disconnection on a FXO ports in CCME 7.1 environment. We have a 2N Analog-GSM gateway attached to a FXO port, and the CCME did not recognise the disconnect tone, so the call was never disconnect (you had to end the call manually). We solved this problem analyzing the discconnect tone an creating a custom cptone:

voice class custom-cptone 2n-gsm
dualtone disconnect
  frequency 425
  cadence 330 330

This is the configuration of the voice-port:

voice-port 0/1/0
supervisory disconnect dualtone mid-call
supervisory custom-cptone 2n-gsm
cptone ES
timeouts call-disconnect 1
timeouts wait-release 1
timing sup-disconnect 50
connection plar 3001
impedance complex2

caller-id enable

Although it works, now we have detected a minor problem: the call takes about 2-3 seconds to be disconnected, so when someone is recording a message in the voicemail it records the disconnect tone during 2-3 seconds at the end of the message. I have changed the timeouts values with no results. Does anybody know how to fix it?

Thanks in advance.


I have the same minor problem: the disconnect works, but it takes 2-3 secconds.

Do you found something about it?

Hello, I have not find out any solution for this problem. Really it is not critical, but I recommend, if you can, to use BRI-GSM gateways, they do not fail.


Ok, thank you for your reply!

Walter Solano
Rising star

This is due to a disconnect suppervision problem, there are several ways to indicate to the FXO port that the calls is been disconnect. The best way to solve this will be contact your service provider and ask them witch method they are using but must of the times they do not know that.

This is a very helpful document that explains each metoth and how to troubleshoot them and the proper configuration that you should have to avoid this kind of issues.

BTW the best way to find out the method that you service provider is using is gathering the output of the "debug vpm singnal" there you will find that information


Walter    Solano

CCNA Voice

UCCX  Specialis

Thank you very much, Victor!

I have configured a UC500 and I had the same problem with disconnection tone. When a customer hang up a call during the AutoAttendant, the call continued ringing until somebody answered.

I read Victor answer, and it worked!

However, I used cadence 200 200, instead of 330 330.

I know you analized your disconnect tone, so it depends on the Service Provider.

I don't know if there is a delay in the desconnection, it seems to work ok.


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