52 Voice API Programming Guide — June 2005
Call Progress Analysis
TID_RNGBK2
Ringback (detected as dual tone)
TID_SIT_ANY
Catch all (returned for a Special Information Tone sequence or SIT sequence that falls outside
the range of known default SIT sequences)
TID_SIT_INEFFECTIVE_OTHER or
TID_SIT_IO
Ineffective other SIT sequence
TID_SIT_NO_CIRCUIT or
TID_SIT_NC
No circuit found SIT sequence
TID_SIT_NO_CIRCUIT_INTERLATA or
TID_SIT_NC_INTERLATA
InterLATA no circuit found SIT sequence
TID_SIT_OPERATOR_INTERCEPT or
TID_SIT_IC
Operator intercept SIT sequence
TID_SIT_REORDER_TONE or
TID_SIT_RO
Reorder (system busy) SIT sequence
TID_SIT_REORDER_TONE_INTERLATA or
TID_SIT_RO_INTERLATA
InterLATA reorder (system busy) SIT sequence
TID_SIT_VACANT_CIRCUIT or
TID_SIT_VC
Vacant circuit SIT sequence
Some of these tone identifiers may be used as input to function calls to change the tone definitions.
For more information, see Section7.8 , “Modifying Default Call Progress Analysis Tone
Definitions on DM3 Boards”, on page 57.
7.5.3 Ringback Detection
Call progress analysis uses the tone definition for ringback to identify the first ringback signal of an
outgoing call. At the end of the first ringback (that is, normally, at the beginning of the second
ringback), a timer goes into effect. The system continues to identify ringback signals (but does not
count them). If a break occurs in the ringback cadence, the call is assumed to have been answered,
and call progress analysis terminates with the reason CR_CNCT (connect); the connection type
returned by the ATDX_CONNTYPE() function will be CON_CAD (cadence break).
However, if the timer expires before a connect is detected, then the call is deemed unanswered, and
call progress analysis terminates with the reason CR_NOANS.