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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

Events

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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