This Recommendation specifies the method for measuring longitudinal conversion loss (9 kHz - 30 MHz) of the telecommunication cable and telecommunication port of the equipment used in analogue and digital communication systems by using the transmission measurement method; it also presents the suggestion of the admissible value for the unbundling condition. This Recommendation is in agreement with the principles@ the nomenclature and the definitions@ addressed in [ITU-T O.9] and in [ITU-T G.117]@ which considers the transmission aspects of unbalance about earth.