1. Define (if necessary) the TAPI device on which the calls must be detected. Use the functions:
   

   Versions 09 and later tapiCapability New in version 09 tapiCapability tapiCapability	Returns the characteristics of a telephony device.
   Versions 09 and later tapiDevice New in version 09 tapiDevice tapiDevice	Selects the TAPI device that will be used during the following telephony operations: tapiDial, tapiListen, tapiDeviceParameter, tapiChangeDeviceParameter.
   Versions 09 and later tapiDeviceList New in version 09 tapiDeviceList tapiDeviceList	Lists the TAPI 2.0 and TAPI 3.1 compatible devices installed on the current computer.
2. Start the detection of incoming calls with tapiListen. This function runs a specific WLanguage procedure. This procedure will be automatically run when an incoming call is detected.
3. In this procedure, you can:
   • find out the status of the call via the following constants:
     • tapiLineBusy: The line is currently busy.
     • tapiLineConnected: The line is connected.
     • tapiLineDialing: Dialing in progress.
     • tapiLineDialTone: The line gets a dial tone
     • tapiLineDisconnected: The correspondent has hung up
     • tapiLineProceeding: The call is dialed: searching for the correspondent
     • tapiLineRingBack: Ringing in progress
     • tapiNewCall: New call detected waiting for an answer or for a reject.
     • tapiCallInformation: The additional information (presentation of the number) is available. In most cases, this information will be available after the fist ring.
   • manage the call via the following functions:
     • finding out the characteristics of the incoming call:
       

       Versions 09 and later tapiCallDuring New in version 09 tapiCallDuring tapiCallDuring	Returns the duration of the call (difference between the start date and time of call and the end date and time of call).
       Versions 09 and later tapiCallEnd New in version 09 tapiCallEnd tapiCallEnd	Returns the date and time of the end of call.
       Versions 09 and later tapiCallerID New in version 09 tapiCallerID tapiCallerID	Used to find out the calling phone number (the one that calls).
       Versions 09 and later tapiCallIsOver New in version 09 tapiCallIsOver tapiCallIsOver	Used to find out whether the incoming or outgoing call is ended.
       Versions 09 and later tapiCallStart New in version 09 tapiCallStart tapiCallStart	Returns the date and time of the beginning of call (incoming or outgoing call).
     • perform specific operations:
       

       Versions 09 and later tapiAnswerCall New in version 09 tapiAnswerCall tapiAnswerCall	Answers an incoming call that was detected.
       Versions 09 and later tapiKeyPressed New in version 09 tapiKeyPressed tapiKeyPressed	Used to find out the history of the keys pressed on the phone keypad since the last call to tapiKeyPressed.
       Versions 09 and later tapiPlay New in version 09 tapiPlay tapiPlay	Plays a sound file (.WAV) for the specified line.
       Versions 09 and later tapiRecord New in version 09 tapiRecord tapiRecord	Saves the current communication as a".WAV" file.
       Versions 09 and later tapiSendKey New in version 09 tapiSendKey tapiSendKey	Allows you to simulate the use of phone keys.
       Versions 09 and later tapiStop New in version 09 tapiStop tapiStop	Forces the reading of a pre-recorded message to stop (tapiPlay).

       
       Caution:
       This WLanguage procedure being run in a thread, all the constraints of the threads must be complied with (no window opening, no timer management, no event management, ...). See Managing threads with WINDEV for more details.
       We recommend that you limit the number of processes performed in this procedure. Indeed, during the duration of the call, the detection of the other calls (as well as all the telephony events) is frozen. If long processes must be performed, we advise you to process the call in the main thread of the application (see the example below).
4. To end the session for detecting the incoming calls, use tapiStopCallDetection.

Example used to manage the incoming calls in the main thread

• Code for declaring the global variables of the window used for call detection. The different events used to manage the calls in the main thread of the application are declared in this code.
  
  GLOBAL
  gnEventID is int
  // Implement an event to manage the incoming calls in popup
  IF Event("DetectedCall", "*.*", "PhoneCall") = 0 THEN
  Error("Unable to manage the popup for call detection", ErrorInfo())
  END
  IF Event("EndDetectedCall", "*.*", "EndPhoneCall") = 0 THEN
  Error("Unable to manage the popup for call detection", ErrorInfo())
  END
  IF Event("DetectedCallIdentifier", "*.*", "PhoneCallInfo") = 0 THEN
  Error("Unable to manage the popup for call detection", ErrorInfo())
  END
  
• Initialization code of window: this code is used to start the procedure for call detection.
  
  // Start the service for call detection
  IF tapiListen("IncomingCall", tapiOptionMediaModeFax, "CallDetection") THEN
  // The service for call detection is started
  Message("Call detection enabled")
  ELSE
  // The service for call detection is not started
   Error("Unable to start the call detection" + CR + ...
  "Error details:"+ CR + ErrorInfo(errMessage))
  END
  
• Procedure for call detection:
  This procedure is used to detect the incoming calls.
  For each incoming call, the characteristics of the call are transmitted to the main thread by PostMessage.
  
  PROCEDURE CallDetection(nServiceID, nCallID, nStatus)
  // WARNING:
  // The processes performed by this procedure are called from a thread
  // The display should be done via the main thread
  // (this is why PostMessage is used)
  // The "Trace" function must be used to debug this process
  // detection of incoming calls
  SWITCH nStatus
  // Detect a new call:
  // Note: Additional information will be available after the fist ring
  CASE tapiNewCall:
    // Signal to the main window that a new call is arriving
    // to open a popup
    PostMessage(Handle(Window_Call), "PhoneCall", nCallID, nStatus)
    // Information about the call is available
  CASE tapiCallInformation:
    // Signal to the main window that a new call is arriving
    // to open a popup
    PostMessage(Handle(Window_Call), "PhoneCallInfo", nCallID, nStatus)
    // The line was hung up
  CASE tapiLineDisconnected:
    // Signal to the main window that a new call is arriving
    // to open a popup
    PostMessage(Handle(Window_Call), "PhoneCallEnd", nCallID, nStatus)
  END