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cdiStartDTMFDetector

Description

Enables the DTMF detector.

Prototype

DWORD cdiStartDTMFDetector (CTAHD ctahd,
CDI_DTMFDETECTOR_PARMS *parms )
ctahd CTA context handle.
parms Pointer to structure containing DTMF detection parameters. Specify NULL to use the default values.

typedef struct
{
DWORD size;
DWORD onqualtime;
DWORD offqualtime;
DWORD DTMF_mode;
} CDI_DTMFDETECTOR_PARMS

Return Values

SUCCESS
CTAERR_OUT_OF_RESOURCES
The DSP does not have enough MIPS to satisfy the request. Retry later.
CTAERR_INVALID_STATE
The port must be off-hook to invoke this function.
CTAERR_FUNCTION_ACTIVE
This function has already been invoked, and the DTMF detector is active.
CTAERR_INVALID_CTAHD
The CTA handle is invalid.
CTAERR_BOARD_ERROR
The board is overheating, and has reached the Protection state. At this stage, the board will not accept nor place any calls on any ports. Refer to Section 4.5 for details.
CTAERR_BAD_ARGUMENT
An argument is not in the valid range.

Events

CDIEVN_DTMF_STARTED
A DTMF tone is being detected. The event value field contains the ASCII representation of the key. Note: The DTMF_mode parameter in CDI_DTMFDETECTOR_PARMS determines when this event is reported (see below).
CDIEVN_DTMF_ENDED
The DTMF tone currently being detected has just ended.

Details

When a station is off-hook, the DSP can detect DTMF tones and return their values to the application. To start DTMF detection, invoke cdiStartDTMFDetector. In the invocation, pass a pointer to the CDI_DTMFDETECTOR_PARMS structure. The structure contains the following fields: Field Description size Size of this structure. onqualtime Minimum duration for a DTMF (in ms). Tones shorter than this duration are ignored. Default is 30 ms. offqualtime Minimum duration of silence after a DTMF (in ms). If two identical DTMFs follow one another, and the interval of silence between the tones is shorter than offqualtime, the detector considers them a single DTMF instance. Default is 30 ms. DTMF_mode Determines when the CDIEVN_DTMF_STARTED event is sent to the application: 0 Event is sent after the qualification time (onqualtime). 1 Event is sent when the key is released.
If the board is running in enhanced mode, the DSP automatically stops DTMF detection for a station when the station is placed on-hook (CDIEVN_ON_HOOK is returned). Otherwise, invoke cdiStopDTMFDetector to stop DTMF detection. (Refer to Section 3.2 for more information about enhanced mode.)
For more information about DTMF detection, refer to Section 3.6.

See Also

cdiStopDTMFDetector

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