Methods and systems for transmitting a discrete information over a communication path comprising analogue communication lines and a pulse-code modulation (PCM) channel are considered, which methods and systems allow to increase the data transfer rate over the entire path up to the data transfer rate in the PCM channel irrespective of the quality of analogue communication lines really employed. In this case, the spectrum of signal being transmitted over the analogue communication line is selected such that the information transfer rate over this analogue communication line is equal to the information transfer rate over the PCM channel, and the number of quantization levels for samples being transmitted over the analogue communication line is the least possible for this analogue communication line. During the conversion of the analogue signal into the PCM channel signal, the sampling rate of this signal is decreased in proportion to the ratio of the number of quantization levels for samples being transmitted over the PCM channel to the number of quantization levels for samples being transmitted over the analogue communication line.