This function generates a beep on the line. The line must be a WAV user and the Wave driver must be involved in the call. The only supported value for dwToneMode is lineToneMode_Beep. Custom tones are not supported, so dwNumTones must be set to 0.

LONG
WINAPI
lineGenerateTone(
HCALL hCall, 
DWORD dwToneMode, 
DWORD dwDuration, 
DWORD dwNumTones, 
LPLINEGENERATETONE const lpTones 
);