(Page 4 of 8 in this chapter)
5.3 Detecting DTMFs
- AG boards are capable of detecting DTMF digits. AG Access provides an interface for collecting digits (DTMFs) in your application, which is discussed later in this manual. Digit collection assumes that DTMF detection is enabled.
- All protocols (including NOCC) default to running the DTMF detector when a call is in the Connected state. Detection parameters are loaded when the protocol is started.
- You can manually start or stop the DTMF detector using these functions:
5.3.1 DTMF Detection Parameters
- The DTMF detector parameter information is stored in the ADI_DTMFDETECT_PARMS structure. For more information about these parameters, refer to the AG Access Function Reference Manual. Refer to Figure 14 for an illustration of these parameters.
- You can modify the DTMF detector's default behavior by specifying the following arguments when invoking adiStartProtocol or adiStartDTMFDetector:
- onqualtime - The minimum duration, in milliseconds, of a recognized
DTMF signal before a DTMF-begin event is sent.
- onqualampl - The minimum signal level, in dBm, recognized as a DTMF
signal.
- offqualtime - The minimum duration, in milliseconds, of absence of a
recognized DTMF signal before a DTMF-end event will be sent.
- offqualampl - The minimum signal level in dBm to maintain recognition of
a DTMF signal once recognition has started.
Figure 14. DTMF Detection Parameters
- The remaining parameters in the structure (onthreshold and offthreshold) should not be modified. They are parameters for the DSP algorithms and are included in the structure for diagnostic purposes when working with NMS Developer Support.
5.3.2 Terminating DTMF Detection
- adiStopDTMFDetector immediately terminates DTMF detection. AG Access generates an ADIEVN_DTMFDETECT_DONE event with the value set to CTA_REASON_STOPPED.
- AG Access may also generate the ADIEVN_DTMFDETECT_DONE event with an error code, ADIERR_xxx or CTAERR_xxx, if the function is started incorrectly.
(Page 4 of 8 in this chapter)
tech_support@nmss.com
Copyright © 1997, Natural MicroSystems, Inc. All rights
reserved.