Voice API Programming Guide — June 2005 75
Call Progress Analysis
ca_lower2frq
Lower bound for second tone in Hz. Default: 0.
ca_upper2frq
Upper bound for second tone in Hz. Default: 0.
ca_time2frq
Minimum time for second tone to remain in bounds. Default: 0 (10 msec units).
ca_mxtime2frq
Maximum allowable time for second tone to be present. Default: 0 (10 msec units).

Third Tone

The following fields in the DX_CAP are used for frequency detection for the third tone.
Frequencies are specified in Hertz, and time is specified in 10 msec units. To enable detection of
the second and third tones, you must set the frequency detection range and time for each tone.
Note: This tone is disabled initially and must be activated by the application using these variables.
ca_lower3frq
Lower bound for third tone in Hz. Default: 0.
ca_upper3frq
Upper bound for third tone in Hz. Default: 0.
ca_time3frq
Minimum time for third tone to remain in bounds. Default: 0 (10 msec units).
ca_mxtime3frq
Maximum allowable time for third tone to be present. Default: 0 (10 msec units).
7.15.3 Obtaining Tri-Tone SIT Frequency Information
Upon detection of the specified sequence of frequencies, you can use extended attribute functions
to provide the exact frequency and duration of each tone in the sequence. The frequency and
duration information will allow exact determination of all four SIT sequences.
The following extended attribute functions are used to provide information on the frequencies
detected by call progress analysis.
ATDX_FRQHZ( )
Frequency in Hz of the tone detected in the tone detection range specified by the DX_CAP
ca_lowerfrq and ca_upperfrq parameters; usually the first tone of an SIT sequence. This
function can be called on non-DSP boards.
ATDX_FRQDUR( )
Duration of the tone detected in the tone detection range specified by the DX_CAP
ca_lowerfrq and ca_upperfrq parameters; usually the first tone of an SIT sequence (10 msec
units).
ATDX_FRQHZ2( )
Frequency in Hz of the tone detected in the tone detection range specified by the DX_CAP
ca_lower2frq and ca_upper2frq parameters; usually the second tone of an SIT sequence.