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UC320 - Italy - Fxo - Issue with disconnect tone

Dear support,

I'm continuing to have issues with the disconnect tone detection during a call via fxo trunk.

I tried the auto detection tool several times, no way. I get 10 minute long voicemail messages and disconnection problems.

I'm attaching a technical note about pstn impedences in italy. Could you please take a look on it and help me finding the correct values?

Thanks in advance


5 Replies 5


Hi Riccardo,

According to the "nota tecnica" the following conditions must be met for Disconnect Tone:

Una frequenza di 425 Hz (+/-15) e un livello di –15dBm (+/-4).  I singoli toni (di On e Off) hanno sulla durata presentata una tolleranza del 10%.

Congestione 0.2  (on)  0.2 (off)

In UC320W terms the following is the Disconnect tone that we should be looking for:  425@-15;1(.2/.2/1)

However to take transmission line signal loss into effect, a better value would be something like this:  425@-25;1(.2/.2/1)  However, the actual value received by the UC320W may be different, thus only an audio capture on the FXO can allow us to verify the actual values.

Please open a case with the Cisco Small Business Support Center where they will perform an audio capture to confirm the frequency and duration of tones needed to terminate far end calls that hang up.  They will then put those values into your UC320W.

The following page contains the pertinent contact list.

Best regards,


Dear Julio,

I'm quite familiar with the values that you've posted. I've got experience with asterisk and many voip/pstn adapters. Can I try myself to do this? I can't find any menu to do this...


Hi Riccardo,

Unless we have a definitive capture of the inbound disconnect tone, for us to analyze and provide the best value to set in the UC320W, it would be hard to guess the value needed to correctly disconnect.
BTW, since I am back in office I verified the UC320W by default sets the Italy region disconnect tone detection as the following:


However, since you are not getting disconnect based on the above setting, I suggest you call in to the Cisco Small Business support center and have them perform an Audio capture of the inbound disconnect tone; the support engineer can then proceed to enter the correct value on your UC320W.

Please also take a look at the Private Message I sent you.

Best regards,



don't assume that attenuation value can be assumed  in a countly like italy that has variety of telcos. They all should range in good values anyway,

Hello to everyone.

I'm sorry to recall this thread after 2 years, but I'm experiencing the same problem.

My italian Telco is Fastweb. I had the same UC320W together with the same provider and hardware (a 2801 acting like ATA) for more than a year without having any issues.

Now we moved our office to another location, so Fastweb reconfigured the 2801 with new parameters.

The service is exactly the same, but now we have problem to disconnect calls.

When the FXO trunk is ready state you can make a call, but when you disconnect, the FXO trunk remain in No service state. To revive the trunk we just make a call on that PSTN number from an external line.


Have you any idea?




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