These properties allow you to monitor for silence during a call, if the device is capable. Voice modems that use the UnimodemV Telephony Service Provider (TSP) do not support silence monitoring.
The Call.MonitorSilence.Active and Call.MonitorSilence.Duration properties can be set at any time.
See the etLine.OnSilence event for more information.
Call.MonitorSilence.Active
Call.MonitorSilence.Duration
ActiveX: etLine.CallMonitorSilenceActive
Type: Boolean
When: Run-Time
Read/Write: Read and Write
Edition: Professional, Enterprise
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Set this property to true to begin monitoring for silence and set it to false to stop monitoring for silence. The call must be in the connected state meaning that the etLine.OnConnected event must have been fired. This property may NOT be set to True before the call is connected. There is no need to set this property to false at the end of a call.
Availability: This property may be set to True only if the bit flag LINECALLFEATURE_MONITORTONES is set in the property etLine.Address.Capabilities.CallFeatures.
ActiveX: etLine.CallMonitorSilenceDuration
Type: Integer
When: Design-Time and Run-Time
Read/Write: Read and Write
Edition: Professional, Enterprise
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When Call.MonitorSilence.Active is set to true then the telephony device will monitor for silence. The OnSilence event will fire when the device detects silence equal to the number of milliseconds defined in this property. 1000 milliseconds is equavalent to 1 second.
We have found that different telephony devices can work somewhat differently within the framework of TAPI. This seems to hold true for the monitoring for silence feature! The following is an outlined of how silence detection works on three different telephony boards; PhoneRider and Dialogic.
1. Select the telephony device
2. Set the etLine.MonitorSilenceDuration on the Call tab to 1000 milliseconds (1 second)
3. Set etLine.MonitorSilenceActive = true using the TeleScope menu option
4. Activate the telephony device
5. Make a call
6. Answer the ringing telephone and say "Hello"
7. The etLine.OnConnected event fires which causes the monitoring of silence to begin
8. The etLine.OnSilence event fires once after the duration of silence is detected
Thus, the first silence detection event occurs the same way for each of the three devices. After that, however, things change a bit as explained below.
On the PhoneRider device:
9. The etLine.OnSilence event fires about every silence detection interval
On the Dialogic board:
9. Create voice energy on the line. This can be done by speaking through the phone or playing a wave file
with the etPlay TeleScope.
10. The etLine.OnSilence event fires once
To cause another detection step 9 must be repeated.
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