Abstract: A fax monitoring apparatus includes one or more line interface circuits to simultaneously detect and analyze audio signals produced on any given telephone line by two connected fax machines, analyzing circuitry to analyze and interpret the audio signals to form a compressed fax image, expansion circuitry, to expand the compressed fax image into a bit-mapped image, memory, to store the compressed fax image and/or the bit-mapped image, and display to display the bit-mapped image of the original fax transmission. A method for monitoring and analyzing the activity of a telephone line includes the steps of sampling the voltage of the telephone line to be monitored, calculating the mean value of the voltage from the samplings, comparing the mean value of the voltage with a reference voltage defined as the mean voltage obtained during the previous time interval, replacing the value of the reference voltage with the mean value, and upon activation, recording the activity of the telephone line.

Abstract: A fax monitoring apparatus comprises one or more line interface circuits to simultaneously detect and analyze audio signals produced on any given telephone line by two connected fax machines, analyzing circuitry to analyze and interpret the audio signals to form a compressed fax image, expansion circuitry to expand the compressed fax image into a bit-mapped image, memory to store the compressed fax image and/or the bit-mapped image, and display to display the bit-mapped image of the original fax transmission.