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CS410 not detecting disconnect tone on PSTN


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Scenario is very simple to reproduce.

Inbound PSTN call routed to AA, if calling party disconnects call at this time the CS410 does not detect the disconnect tone and keeps the line active and in use.

Clearing the call out from the web m/ment and disconnecting the PSTN line both obviously resolve the issue but this is not a feasible option.

Also occurs if call is terminated at an extensions VM box.

Current f/w is but also occurs on earlier f/w versions.


Any advice would be appreciated.

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I can confirm we've experienced this exact same scenario, and we actually have a support case open about it.


In our case the AA was Exchange 2007, but like you mention the line stayed off hook for over 14 minutes, despite the caller hanging up, until the cable was physically disconnected from the CS410 to reset the line.


We are also using the version 3.4 firmware.


I wonder if this is an issue with the Australian tone settings? The only PSTN settings on this version for the CS410 seem to be FX Impedance and CPC Duration (Complex and 400 respectively in our setup), so I presume the others are set automatically for Australia based on the regional settings on the device?

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Did you try to use the tone detection of the trunk? This is a generic tone detector built into the PBX (not the gateway). It is pretty generic, should also work in Australia.

Thank you for that after enabling "Requires busy tone detection" (In the PSTN g/w trunk settings) the call is cleared out after approx 5 seconds.

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Calling Party Control (CPC) is very standard on all modern switches worldwide so you should not have to try to detect busy signals. It wastes time (the trunk is not usable during this period) and errors can occur mid-call with conference calls, laughing, and other noises.


The phone company actually drops power on the trunk for a time and that is what the CS410 should detect. Play with the detection time settings and sees if you can get it to work - it is a much better solution than using tone detection. Otherwise you may have weird problems later. Do you know what kind of switch your phone company is using?


Here is a good write up on CPC and some other trouble shooting ideas:





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