Telco Call Progress
Generator/Detector
for TMS320C25/'C5x
by DSP Software Engineering, Inc.

Software Overview

Call Progress is a tonal-signaling standard used to acquire connections between subscribers in 
telephone network systems. Various Call Progress tones indicate the status of incoming or outgoing 
phone calls. DSPSE's implementation provides full Call-Progress detection functionality on a 
TMS320C25/'C5x processor. The Call Progress detector operates on linear-PCM samples. Call Progress 
uses eight frequencies representing call status. Each Call Progress tone also requires an "on time" 
and an "off time." The chart below summarizes the North American Call Progress tones this 
implementation supports:
Signal
Frequencies
On Time (s)
Off Time (s)
Dial Tone
350, 440 Hz
Continuous
None
Busy Signal
480, 620 Hz
0.5
0.5
Congestion Signal
480, 620 Hz
0.2
0.3
Ring Back
440, 480 Hz
2.0
4.0
Receiver Off Hook
1400, 2060, 2450, 2600 Hz
0.1
0.1

Features and Benefits

•	C callable functions
•	SPOX compatible
•	Easily modified for different tones and on/off times

Processor and System Requirements

•	Devices supported: TMS320C25, TMS320C5x
•	Algorithm category: Telecommunications
•	Requirements:
All memory requirements are in units of 16-bit words. The MIPs ratings presented require the listed 
amounts of dual-access RAM (DARAM), zero-wait-state program and data memory, and sample by sample 
processing. All measurements were made using an executable demonstration built for a third-party PC 
plug-in board.
Function
MIPS
DARAM
Data
Program
Detector 
2.2
45
0
0.5 k

User Functions

The Call Progress implementation consists of two independent, C-callable functions that perform 
detection and initialize the call-progress detector. The detector  interfaces with linear-PCM 
samples and tone status words.
Call Progress Receiver
icallpro (...)
Dynamically allocates and initializes data memory for detector
callpro (...)
Detects call-progress tones in linear-PCM samples

Algorithm Verification

•	Call DSPSE for verification details

Availability

•	Source and object code currently available for licensing.

Company Background and Contact Information

DSP Software Engineering, Inc (DSPSE), founded in 1989, is a leading provider of highly-complex 
digital-signal-processing software used in telecommunications and multimedia applications such as 
computer telephony, digital wireless, PSTN, and satellite communications, and videoconferencing. 
DSPSE sells its products to OEMs and directly to manufacturers of telecommunications products. 
DSPSE provides the complete solution to your DSP needs with DSP solution software packages and 
individual DSP software component algorithms and expert service.
Contact:	DSP Software Engineering, Inc
		175 Middlesex Turnpike
		Bedford, MA 01730  USA
		(617) 275-3733
		Fax: (617) 275-4323
		e-mail:  info@dspse.com
		www:  http://www.dspnet.com