Intel 52377002 7.16 Cadence Detection in Basic Call Progress Analysis (Springware Only)

78 Voice API Programming Guide — June 2005
Call Progress Analysis
7.16 Cadence Detection in Basic Call Progress Analysis
(Springware Only)
Cadence detection is a component of basic call progress analysis. The following topics discuss
cadence detection and some of the most commonly adjusted cadence detection parameters in basic
call progress analysis:
•Overview
•Typical Cadence Patterns
•Elements of a Cadence
•Outcomes of Cadence Detection
•Setting Selected Cadence Detection Parameters
•Obtaining Cadence Information
7.16.1 Overview
The cadence detection algorithm has been optimized for use in the United States standard network
environment.
Caution: This discussion of cadence detection in basic call progress analysis is provided for backward
compatibility purposes only. You should not develop new applications based on basic call progress
analysis. Instead you should use PerfectCall call progress analysis. For information on cadence
detection in PerfectCall call progress analysis, see Section 7.11, “Call Progress Analysis Tone
Detection on Springware Boards”, on page65.
If your system is operating in another type of environment (such as behind a PBX), you can
customize the cadence detection algorithm to suit your system through the adjustment of the
cadence detection parameters.
Cadence detection analyzes the audio signal on the line to detect a repeating pattern of sound and
silence, such as the pattern produced by a ringback or a busy signal. These patterns are called audio
cadences. Once a cadence has been established, it can be classified as a single ring, a double ring,
or a busy signal by comparing the periods of sound and silence to established parameters.
Notes: 1. Sound is referred to as nonsilence.
2. The algorithm used for cadence detection is disclosed and protected under U.S. patent 4,477,698
of Melissa Electronic Labs, and other patents pending.
7.16.2 Typical Cadence Patterns
Figure 6, Figure 7, and Figure 8 show some typical cadence patterns for a standard busy signal, a
standard single ring, and a double ring.