A method for automatically monitoring telephone calls with at least two call partners, comprising the following steps: - receiving a digital audio data signal of at least one call partner, wherein the digital audio data signal has been produced by compression from an analogue audio data signal of the respective call partner, wherein the digital audio data signal comprises a plurality of digital audio data packets of a predetermined length L arranged in a sequential order, wherein each audio data packet represents a sequence of a plurality of bytes and a level height is assigned to each byte, - modifying the digital audio data signal of at least one call partner, wherein the following steps are carried out sectionwise for the entire digital audio data signal comprising N digital audio data packets of the respective call partner per time unit: - automatically selecting a predetermined proportion of the N digital audio data packets per time unit in the respective section, - automatically replacing each of the selected audio data packets with a respective replacement audio data packet of the same length L, wherein the replacement audio data packet ▪ has a modified sequence of level heights compared to the sequence of the respective selected audio data packet or ▪ has the same average level height as the respective selected audio data packet, so that an information-reduced audio data signal is produced, and - storing the respective information-reduced audio data signal. - receiving a digital audio data signal of at least one call partner, wherein the digital audio data signal has been produced by compression from an analogue audio data signal of the respective call partner, wherein the digital audio data signal comprises a plurality of digital audio data packets of a predetermined length L arranged in a sequential order, wherein each audio data packet represents a sequence of a plurality of bytes and a level height is assigned to each byte, - modifying the digital audio data signal of at least one call partner, wherein the following steps are carried out sectionwise for the entire digital audio data signal comprising N digital audio data packets of the respective call partner per time unit: - automatically selecting a predetermined proportion of the N digital audio data packets per time unit in the respective section, - automatically replacing each of the selected audio data packets with a respective replacement audio data packet of the same length L, wherein the replacement audio data packet ▪ has a modified sequence of level heights compared to the sequence of the respective selected audio data packet or ▪ has the same average level height as the respective selected audio data packet, so that an information-reduced audio data signal is produced, and - automatically selecting a predetermined proportion of the N digital audio data packets per time unit in the respective section, - automatically replacing each of the selected audio data packets with a respective replacement audio data packet of the same length L, wherein the replacement audio data packet ▪ has a modified sequence of level heights compared to the sequence of the respective selected audio data packet or ▪ has the same average level height as the respective selected audio data packet, so that an information-reduced audio data signal is produced, and ▪ has a modified sequence of level heights compared to the sequence of the respective selected audio data packet or ▪ has the same average level height as the respective selected audio data packet, - storing the respective information-reduced audio data signal.