Abstract: A call progress signal monitor includes a translation circuit for generating data signals indicative of predetermined signal characteristics in a TDM PCM signal channel. A processor implemented detection circuit is responsive to the data signals for detecting call progress tones and silence. The translation circuit includes a translation ROM for assigning PCM signal samples with code values in a range with maximum and minimum limits. A comparator generates a comparison value signal in response to the code values of an instant sample and an immediately previous sample. An encoding ROM generates a trend data byte in response to an instant comparison value signal and a plurality of consecutive previous comparison value signals. The instant code value and the instant trend data byte comprise data signals for identification of the progress tones and silence occurrences by the detection circuit.