Caller ID, DTMF, and
Call Progress Tone Detectors
by Atlanta Signal Processors, Inc.

Software Overview

Call progress tones are used in telephone networks to connect and indicate status information, to 
simplify operation, to reduce calling errors, and to provide interactive response to telephony 
systems. Conditions like busy line, ringing called party, bad number, and others have distinctive 
tone frequencies and cadences. DTMF tones are used to dial and interact with remote telephony 
systems. CallerID information identifying the calling party is available on most phone networks and 
the encoded -CallerID information is provided between the first and second ring of the received 
phone call. The ASPI Call Progress Tone Detectors provide separate modular functions for decoding 
CallerID information and for detecting and generating call progress tones.

Call Progress Tone
Frequencies (Hz)
On Time (s)
Off Time (s)
Dial tone
350, 440
Continuous
None
Busy signal
480, 620
0.5
0.5
Congestion signal
480, 620
0.2
0.3
Ring signal
440, 480
2.0
4.0
Receiver off hook
1400, 2060, 2450, 2600
0.1
0.1
CallerID
1200/2200
Variable
Variable

Features and Benefits

•	Code is C callable and relocateable
•	Multiple channels can run on single TMS320C3x DSP
•	Object-based interface

Processor and System Specifications

•	TMS320C3x processor usage and memory requirements depends on number of channels and the number of 
tone detectors activated. Performance data available upon request.

Usage Limitations or Performance Considerations

•	None

Algorithm Verification

•	The implementation of the individual generators and detectors has been extensively tested.

Availability

•	Available from Atlanta Signal Processors, Inc. Object code, source code, and run-time license 
provided by Atlanta Signal Processors, Inc.


Company Background and Contact Information

Atlanta Signal Processors was founded in 1981 by Ronald W. Schafer, Thomas P. Barnwell III, and 
Russell M. Mersereau, three Professors of Electrical Engineering at the Georgia Institute of 
Technology with over 80 years of experience in the field. The company has focused its efforts on 
developing tools for professional signal-processing design engineers and now offers digital 
signal-processing hardware and software products to DSP designers worldwide.

Contact:	Atlanta Signal Processors, Inc.
		1375 Peachtree St. NE, Suite 690
		Atlanta, Georgia  30309-3115
		(404) 892-7265
		Fax: (404) 892-2512
		e-mail: aspi@aspi.com