Question: How can I troubleshoot the UCM6100 if it cannot detect hang-up on the FXO port?

If the UCM6100 cannot detect hang-ups on the FXO port, the FXO port will not be released. This might cause the line always busy, or long voicemail message sent to the extension if the outside caller leaves a voicemail. Please follow the instructions below to troubleshoot the issue.

1. Go to the UCM6100 web GUI->PBX->Analog Trunks page.
2. Select the analog trunk configured for the FXO port.
3. Run "PSTN Detection" by clicking on "Detect" button. This will correct the disconnect method for the analog trunk in order for the UCM6100 to detect the hang-up.

If the issue still persists, users might need check whether the PSTN disconnect tone's energy is high enough to trigger the disconnect detection as configured on the UCM6100's analog trunk. The disconnect threshold value on the UCM6100 can be found in "Busy Tone" and "Congestion Tone" settings. If the "Tone Country" is set to "United States of America (USA)", the busy tone and congestion tone are set as follows:

Busy Tone: f1=480@-50,f2=620@-50,c=500/500

Congestion Tone: f1=480@-50,f2=620@-50,c=250/250

where "-50" is the threshold value to detect the hang-up.

The actual energy (in dB) for threshold "-50" can be calculated as below:

(-50) x 0.1 - 23 = -28 dB

This means the PSTN disconnect tone's energy has to be higher than -28dB in order for the UCM6100 to detect the hang-up. If it's lower than -28dB, on the UCM6100 analog trunk, users will need set the "Tone Country" to "Custom", calculate the threshold value based on the actual PSTN disconnect tone's energy, and change the settings for the "Busy Tone" or "Congestion Tone" in order to meet the disconnect requirement.

Note: To decide whether the PSTN line is using busy tone or congestion tone to hang up the call, users can do a quick test as described below.

1. Make a phone call from outside PSTN line to a UCM6100 extension and establish the call.

2. Hang up the call from the outsider caller.

3. Listen to the tone on the UCM6100 extension side.

If users immediately hear busy tone, please configure the threshold for "Busy Tone". If users hear dial tone first and then busy tone, please configure the threshold for "Congestion Tone".

For example, the actual PSTN disconnect tone is congestion tone and has energy value -33dB, users might change the congestion tone setting to the following:


Category: UCM6100 Series