66 Voice API Programming Guide — June 2005
Call Progress Analysis
7.11.1 Tone Detection Overview
PerfectCall call progress analysis uses a combination of cadence detection and frequency detection
to identify certain signals during the course of an outgoing call. Cadence detection identifies
repeating patterns of sound and silence, and frequency detection determines the pitch of the signal.
Together, the cadence and frequency of a signal make up its “tone definition”.
Unlike basic call progress analysis, which uses fields in the DX_CAP structure to store signal
cadence information, PerfectCall call progress analysis uses tone definitions which are contained in
the voice driver itself. Functions are available to modify these default tone definitions.
7.11.2 Types of Tones
Tone definitions are used to identify several kinds of signals.
The following defined tones and tone identifiers are provided by the voice library on Springware
boards. Tone identifiers are returned by the ATDX_CRTNID() function.
TID_BUSY1
Busy signal
TID_BUSY2
Alternate busy signal
TID_DIAL_INTL
International dial tone
TID_DIAL_LCL
Local dial tone
TID_DIAL_XTRA
Special (extra) dial tone
TID_FAX1
CNG (calling) fax tone or modem tone
TID_FAX2
CED (called station) fax tone or modem tone
TID_RNGBK1
Ringback
TID_RNGBK2
Ringback
The tone identifiers are used as input to function calls to change the tone definitions. For more
information, see Section 7.14, “Modifying Default Call Progress Analysis Tone Definitions on
Springware Boards”, on page 71.