Windows Mobile 6.5
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This function enables and disables the unbuffered detection of digits received on the call. Each time a digit of the specified digit mode is detected, a message is sent to the application indicating which digit has been detected.

LONG WINAPI lineMonitorDigits(
  HCALL hCall,
  DWORD dwDigitModes 


Handle to the call on which digits are to be detected. The call state of hCall can be any state except idle or disconnected.


Digit mode or modes that are to be monitored. If dwDigitModes is zero, digit monitoring is canceled. This parameter uses one or more of the LINEDIGITMODE constants.

Returns zero if the request succeeds or a negative error number if an error occurs. The following table shows the return values for this function.

Value Description


The handle to the call is invalid.


The operation is unavailable.


The call state of hCall is either idle or disconnected.


The operation failed.


The digit mode is invalid.


The resources are unavailable.


Not enough memory is available.


A parameter is uninitialized.

This function is considered successful if digit monitoring has been correctly initiated, not when digit monitoring has terminated. Digit monitoring remains in effect until it is explicitly disabled by calling lineMonitorDigits with dwDigitModes set to zero, until the call transitions to idle, or when the application deallocates its call handle for the call. Although this function can be invoked in any call state, digits are usually detected only while the call is in the connected state.

Each time a digit is detected, a LINE_MONITORDIGITS message is sent to the application passing the detected digit as a parameter.

An application can use lineMonitorDigits to enable or disable unbuffered digit detection. Monitoring of digits on a conference call applies only to the hConfCall, not to the individual participating calls.

This function is for TAPI version 2.0 and later.

Windows Embedded CEWindows CE 1.0 and later
Windows MobileWindows Mobile Version 5.0 and later

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