Developers' Corner - Programmer's Handbook

Coding Tips

Detect DTMF digit using Telephony API (TAPI)

If you are developing TAPI compliant software for Phone Blaster, one feature you would probably use is the DTMF digits detection. For example, if you were to create an auto-answering machine software, then your application would need to detect the DTMF digits. The implementation is quite simple and straight forward. You can use the function lineMonitorDigits to enable the unbuffered detection of digits. You can call this function when the call has been established and the connection is made. Here is a sample code fragment:

    case LINE_CALLSTATE:
	...
	...
	switch(dwParam1) :
		{
		  case LINECALLSTATE_CONNECTED:
			...
			lineMonitorDigits(hCall, LINEDIGITMODE_DTMFEND) ;	
			...
		  break ;
		}	
	break ;

Within the callback function, your application can then monitor the message LINE_MONITORDIGITS which is sent to application whenever a digit is detected.

	case LINE_MONITORDIGITS:
		// add the message processing code here.		  		
    break ;