The DialAnswer sample program demonstrates how the etLine, etPhone, etPlay, and etRecord controls can be used together. It allows the user to both call out (Dial) and receive incoming calls (Answer) , and track the various events fired in the process by the output in the log box. The user can:

• Select from all available telephony devices

• Test the selected device for a dial tone

• Play files when a call is connected

• Cause those files to loop continuously or to only play once

• Modify the volume and gain on the speakerphone, if attached

• Record all or part of a call to a wave file.

NOTE: You can click on any of these event handler routines to be taken right to the source code.

The “Active” checkbox is used to turn the selected line device on, when checked, or off, when not checked. If the control is checked, then the line device is activated by setting the property etLine1.Device.Active = TRUE; if not checked, then the line device is deactivated by setting the property etLine1.Device.Active = FALSE. 

When deactivating the line device, the TAPI phone device is first deactivated by setting the property etPhone1.Device.Active = FALSE. When the line device is inactive, the ButtonDial and ButtonDialTone controls are disabled. 

If there error LINEERR_INVALIDMEDIAMODE is returned when activating the line device, the device is probably not 100% TAPI-compliant. The etLine1.Device.MediaModesActive is set to LINEMEDIAMODE_DATAMODEM and etLine1.Device.Active is once again set to TRUE. We assume that the device is a modem that does not support the voice features, so we attempt to activate the modem in data mode. 

After successfully activating the line device, the ButtonDial and ButtonDialTone controls are enabled. If the CheckBoxPhone is checked and etLine1.Phone.Available = True, indicating that a TAPI phone device is available, then the TAPI phone device is activated by setting the property etPhone1.Device.Active = TRUE. If the property etLine1.TAPI.TSP contains the string "Universal Modem Driver", then the property etPlay1.Volume.Enabled is set to false because voice modems do not support the volume features. 

If the the TAPI line device supports playing wave files ( etLine1.WavePlay.Available = True), then controls CheckBoxPlayOnConnect, EditWaveFile, and CheckBoxLoop are enabled; otherwise they are disabled. 

The UpdatePhoneDisplay routine is called to enable or disable controls having to do with the speakerphone settings.

CheckLoop_Click

The etPlay1.Device.Loop property is set to the value this check box.

ComboDevice_Click

The etLine1.Device.Active property is checked to see if the current device is active. If so, then CheckBoxActive is set to false causing the device to be deactivated. The etLine1.Device.ID is set to the index value of the device chosen in the combo box. If no errors occurred, then the properties etLine1.Privilege.Monitor and etLine1.Privilege.Owner are set to true.

CommandClear_Click

The information in the Memo1 control is cleared.

CommandDialtone_Click

The property is set to etLine1.Call.PhoneNumber = “;W” which indicates to the telephony device to begin the dialing process although wait for a dial tone. The etLine1.Privilege.None and etLine1.Device.MediaModesActive properties are then tested to see if this device has the ability to make a voice call. The etLine1.Call.Dial method is then called. If successful, then then the etLine1.OnDialtone event fires. 

This method of checking for a dial tone may not work with all telephony devices. Not all Telephony Service Providers (TSP) and/or telephony devices support the "W" as a valid "dial-able" character. See the etLine.Call.PhoneNumber property for the list of dial-able characters.

CommandRecord_MouseDown

As long as this button is held down, etRecord1 will record a wave file. etLine1.TAPI.TSP is checked to see if a Dialogic board is being used. If so, then the etRecord1.Source.Format.ID is set to use the wave format "uLaw8000 Hz, 8 bit, Mono". Otherwise, the default "PCM 8000 Hz, 16 bit, Mono" is used. etRecord.Source.Format.FileName is set to a valid path and file name. The correct wave audio device is selected by setting etRecord1.Device.ID to the value of the property etLine1.WaveRecord.ID. Recording is started by setting etRecord1.Device.Active to True.

CommandSPGainApply_Click

The the property etPhone.Speakerphone.Gain is set to the value in the EditSPGain control. The event queue is allowed to be emptied allowing time for the speakerphone to adjust. The EditSPGain control is updated to match the speakerphone’s new gain setting.

etLine1_OnBusy

When this occurs, the etLine1.Call.Hangup method is called.

etLine1_OnCalledID

When the etLine.OnCalledID event fires the etLine1.Call.CalledID.Name and etLine1.Call.CalledID.Number property values are appended to the log.

etLine1_OnCallerID

When the etLine1.OnCallerID event fires, the etLine1.Call.CallerID.Name and etLine1.Call.CallerID.Number property values are appended to the log.

The etLine1.Call.Origin is checked to see if the call is inbound or outbound.

• If this is an outbound call, then silence-monitoring will be used to test for an answering machine. TimerAutomatedAnsweringDevice is enabled, see TimerAutomatedAnsweringDeviceTimer. etLine1.Call.MonitorSilence.Duration is set to monitor for 1.5 seconds of silence and etLine1.Call.MonitorSilence.Active is set to True to begin monitoring for silence.
• If it is an inbound call, then the wave file is played if CheckBoxPlayOnConnect.Checked is set to True. etPlay1.Source.FileName is set to the file in the EditWaveFile control. The correct wave audio device is selected by setting etPlay1.Device.ID to the value of the property etLine1.WavePlay.ID. Playing is started by setting etPlay1.Device.Active = True.

The Enabled property for several buttons is modified.

etLine1_OnConnectedID

When the etLine.OnConnectedID event fires, the etLine1.Call.ConnectedID.Name and etLine1.Call.ConnectedID.Number property values are appended to the log.

etLine1_OnDialtone

When the etLine1.OnDialtone fires, the global State variable is checked to see if the ButtonDialtone button was clicked. If it was, then it is indicated in the log that the dial tone test was successful. Otherwise, it is simply indicated in that log that this event has fired.

If a wave file is currently playing, then it is stopped by setting etPlay1.Device.Active = False. If a wave play device is available, the wave file for the digit will be played. For example, if "1" is received, then etPlay1.Source.FileName will be set to "1" causing the wave file 1.wav to be played by setting etPlay1.Device.Active = True. There are no wave files for the following DTMF tones "*", "#", "A", "B", "C" or "D".

For an example of how to use the Tag parameter, see the etIVR4Line sample program.

etLine1_OnDisconnected

If ButtonDialtone had been clicked and this event occurs, then the etLine1.Call.DisconnectMode property is tested to see if the dial tone was detected. This may not work with some telephony devices because not all Telephony Service Providers (TSP) and/or telephony devices are capable of reporting a disconnect mode.

 If the etPlay1.Device.Active property is True then a wave file is currently playing and must be stopped by setting etPlay1.Device.Active = False. If the etRecord1.Device.Active property is True then a wave file is currently recording and must be stopped by setting etRecord1.Device.Active = False.

 The etLine1.Call.Hangup method is called to hang up the call.

etLine1_OnIdle

The ButtonDialtone and ButtonDial controls are enabled. The ButtonRecord, ButtonAnswer and ButtonHangup are disabled. If the etPlay1.Device.Active property is True then a wave file is currently playing and must be stopped by setting etPlay1.Device.Active = False. If the etRecord1.Device.Active property is True then a wave file is currently recording and must be stopped by setting etRecord1.Device.Active = False.

etLine1_OnRedirectingID

The etLine1.Call.RedirectingID.Name and etLine1.Call.RedirectingID.Number property values are appended to the log.

etLine1_OnRing

The log edit box is updated with a message.

etLine1_OnSilence

If the property etLine.Call.Origin indicates that this is an outbound call, then TimerAutomatedAnsweringDevice is disabled. Monitoring for silence is stopped by setting etLine1.Call.MonitorSilence.Active to False. The current time and the stored time are used to see if 2 seconds have passed since silence detection has been initiated. If silence was detected in less than 2 seconds then the call was probably answered by a human and not an answering machine.

 Answering machine detection in this manner can be reliable although you may have to modify the properties etLine1.MonitorSilence.Duration and TimerAutomatedansweringDevice.Duration.

etPhone1_OnDigitDown

The log edit box is updated with a message.

etPhone1_OnError

The log is updated to indicate that this event has fired.

etPhone1_OnPhoneState

The etPhone1.OnPhoneState event is fired when the current state of the TAPI Phone device changes. The etPhone1.Device.State and etPhone1.Device.StateDetails property values are displayed in the log.

etPhone1_OnSpeakerphoneHookSwitch

The etPhone1.OnSpeakerphoneHookSwitch event is fired when the SpeakerphoneHookSwitch state changes. The current state for the etPhone1.Speakerphone HookSwitch properties are displayed in the log and the RadioButtonSPOffHook and RadioButtonSPOffHook controls are updated.

etPlay1_OnDone

The etPlay1.OnDone event is fired when the wave file has completed playing. The log is updated to indicate that this event has fired.

etPlay1_OnLoaded

The etPlay1.OnLoaded event is fired when the entire wave file has finished loading into memory. The log is updated to indicate that this event has fired.

etPlay1_OnWarning

The etPlay1.OnWarning event fires when a non-fatal error occurs while playing a .WAV file. A message box is popped up to tell the user about it. If the user presses the “Cancel” button, the value of the Continue variable is set to false which causes the file to stop playing.

etRecord1_OnWarning

The etRecord1.OnWarning event fires when a non-fatal error occurs while recording a .WAV file. A message box is popped up to tell the user about it. If the user presses the “Cancel” button, the value of the Continue variable is set to false which causes the file to stop recording.

Form_Resize

Resizes controls to fit the current size of the form.

OptionSPOffHook_Click

The etPhone1.Speakerphone.MicrophoneAndSpeaker property is set to the value of this radio button.

TextSPGain_LostFocus

If the value is outside the valid range for the etPhone.Speakerphone.Gain property, the value is reset.

TimerAutomatedAnsweringDevice_Timer

The timer is disabled so it will not fire again. Monitoring for silence is stopped by setting etLine1.Call.MonitorSilence.Active = False. Since more than 3 seconds has passed since the etLine.OnConnected event has fired and silence was not detected then it is assumed that this calls was answered by an automated answering device. The log is updated to indicated this.

Answering machine detection in this manner can be reliable, but you may have to modify the properties etLine1.Call.MonitorSilence.Duration and TimerAutomatedansweringDevice.Duration.