68 Voice API Programming Guide — June 2005
Call Progress Analysis
The following DX_CAP fields govern ringback behavior:
ca_stdely
Start Delay: the delay after dialing has been completed before starting cadence detection,
frequency detection, and positive voice detection (in 10 msec units). Default: 25 (0.25
seconds).
ca_cnosig
Continuous No Signal: the maximum length of silence (no signal) allowed immediately after
the ca_stdely period (in 10 msec units). If this duration is exceeded, call progress analysis is
terminated with the reason CR_NORB (no ringback detected). Default value: 4000 (40
seconds).
ca_noanswer
No Answer: the length of time to wait after the first ringback before deciding that the call is
not answered (in 10 msec units). If this duration is exceeded, call progress analysis is
terminated with the reason CR_NOANS (no answer). Default value: 3000 (30 seconds).
ca_maxintering
Maximum Inter-ring: the maximum length of time to wait between consecutive ringback
signals (in 10 msec units). If this duration is exceeded, call progress analysis is terminated with
the reason CR_CNCT (connected). Default value: 800 (8 seconds).
7.11.5 Busy Tone Detection
Call progress analysis specifies two busy tones: TID_BUSY1 and TID_BUSY2. If either of them is
detected while frequency detection and cadence detection are active, then call progress is
terminated with the reason CR_BUSY. ATDX_CRTNID() identifies which busy tone was
detected.
To enable busy tone detection, turn on SIT frequency detection in the DX_CAP ca_intflg field. For
details, see Section 7.10.2, “Setting Up Call Progress Analysis Features in DX_CAP”, on page 61.
7.11.6 Fax or Modem Tone Detection
Two tones are defined: TID_FAX1 and TID_FAX2. If either of these tones is detected while
frequency detection and cadence detection are active, then call progress is terminated with the
reason CR_FAXTONE. ATDX_CRTNID() identifies which fax or modem tone was detected.
To enable fax or modem tone detection, turn on SIT frequency detection in the DX_CAP ca_intflg
field. For details, see Section7.10.2, “Setting Up Call Progr ess Analysis Features in DX_CAP”, on
page61.
7.11.7 Loop Current Detection
The dx_dial( ) function does not support loop current detection on DM3 boards.