LINE_MONITORTONE R4_IGK

The LINE_MONITORTONE message is sent when a tone is detected. The sending of this message is controlled with the lineMonitorTones2ISB5VM function.

LINE_MONITORTONE
dwDevice = (DWORD) hCall;

dwCallbackInstance = (DWORD) hCallback;

dwParam1 = (DWORD) dwAppSpecific;

dwParam2 = (DWORD) 0;

dwParam3 = (DWORD) 0;

Parameters

dwDevice

A handle to the call.

dwCallbackInstance

The callback instance supplied when opening the call's line.

dwParam1

The application-specific dwAppSpecific field of the LINEMONITORTONEL9P0D2 structure for the tone that was detected.

dwParam2

Unused.

dwParam3

The "tick count" (number of milliseconds since Windows started) at which the tone was detected. For API versions prior to 0x00020000, this parameter is unused.

Return Values

No return value.

Remarks

The LINE_MONITORTONE message is only sent to the application that has requested the tone be monitored.

Because this timestamp may have been generated on a computer other than the one on which the application is executing, it is useful only for comparison to other similarly timestamped messages generated on the same line device (LINE_GATHERDIGITS, LINE_GENERATE, LINE_MONITORDIGITS, LINE_MONITORTONE), in order to determine their relative timing (separation between events). The tick count can "wrap around" after approximately 49.7 days; applications must take this into account when performing calculations.

If the service provider does not generate the timestamp (for example, if it was created using an earlier version of TAPI), then TAPI will provide a timestamp at the point closest to the service provider generating the event so that the synthesized timestamp is as accurate as possible.