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Walkthrough Wednesdays

Troubleshooting FXO disconnect Signal issue


FXO disconnect signal is a well known issue in FXO setup. the disconnect signal it depends on the PBX/PSTN provider that your voice gateway is connected to. The disconnect signals are different from one vendor to other, Ericson, Siemens, Alcatel,... etc.


You need to take the appropriate disconnect signal from your PSTN provider if it is possible.


you can use the following link to look for your current disconnect signal


if one of the above is not working you need to take pcm captures, find the below link


to take pcm capture use the following command


1. Enable the capture:


    Router(config t)#voice hpi capture buffer 5000000


    Router(config t)#voice hpi capture destination flash:FileName.pcm.dat




2. Start the capture:


    Router#test voice port x/y/z pcm-dump caplog 7


3. Place a call on that port, and disconnect from the far end.


4. After the call has been disconnected from the PSTN side, disable the capture with the command below.


   Be sure to do this, or otherwise the router flash will be full and the router will hang.


   Router#test voice port x/y/z pcm-dump disable


   Router(config t)#no voice hpi capture destination


5. User Cool edit to analyse  .dat file to extract the disconnect tone, or send this file to TAC engineer.