LINE_MONITORTONE message
The TAPI LINE_MONITORTONE message is sent when a tone is detected. The sending of this message is controlled with the lineMonitorTones function.
Parameters
-
hDevice
-
A handle to the call.
-
dwCallbackInstance
-
The callback instance supplied when opening the call's line.
-
dwParam1
-
The application-specific dwAppSpecific member of the LINEMONITORTONE 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 earlier than 2.0, this parameter is unused.
Return value
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 provides a timestamp at the point closest to the service provider generating the event so that the synthesized timestamp is as accurate as possible.
Requirements
| Requirement | Value |
|---|---|
| TAPI version |
Requires TAPI 2.0 or later |
| Header |
|