72 Voice API Programming Guide — June 2005
Call Progress Analysis
The voice driver contains default definitions for each of these tones. The default definitions will
allow applications to identify the tones correctly in most countries and for most switching
equipment. However, if a situation arises in which the default tone definitions are not adequate,
three functions are provided to modify the standard tone definitions:
dx_chgfreq()
specifies frequencies and tolerances for one or both frequencies of a single- or dual-frequency
tone
dx_chgdur( )
specifies the cadence (on time, off time, and acceptable deviations) for a tone
dx_chgrepcnt()
specifies the repetition count required to identify a tone
These functions can be used to modify the tone definitions shown in Table7, “Default Call
Progress Analysis Tone Definitions (Springware)”, on page71. These functions only change the
tone definitions; they do not alter the behavior of call progress analysis itself. When the
dx_initcallp( ) function is invoked to activate call progress analysis on a particular channel, it uses
the current tone definitions to initialize that channel. Multiple calls to dx_initcallp( ) may therefore
use varying tone definitions, and several channels can operate simultaneously with different tone
definitions.
For more information on tones and tone detection, see Section 7.11, “Call Progress Analysis Tone
Detection on Springware Boards”, on page65.
Note: The Learn Mode API and Tone Set File (TSF) API provide a more comprehensive way to manage
call progress tones, in particular the unique call progress tones produced by PBXs, key systems,
and PSTNs. Applications can learn tone characteristics using the Learn Mode API. Information on
several different tones forms one tone set. Tone sets can be written to a tone set file using the Tone
Set File API. For more information, see the Learn Mode and Tone Set File API Software Reference
for Linux and Windows Operating Systems.
7.15 SIT Frequency Detection (Springware Only)
Special Information Tone (SIT) frequency detection is a component of call progress analysis. The
following topics provide more information on this component:
•Tri-Tone SIT Sequences
•Setting Tri-Tone SIT Frequency Detection Parameters
•Obtaining Tri-Tone SIT Frequency Information
•Global Tone Detection Tone Memory Usage
•Frequency Detection Errors
•Setting Single Tone Frequency Detection Parameters
•Obtaining Single Tone Frequency Information