FIELD: telephone equipment. SUBSTANCE: electronic user's circuits have sensitive circuits for current recognition (S) which control current (I) in user's line. User's call is modeled by repeated interruption of alternating calling voltage which induces alternating current in user's line. However, call alternating voltage are switched in proximity of zero level transition. In switching phase, there exists danger of generation and running of current which is caused by capacitance load of connected user's circuit, which causes user's line current leading to false line recognition. Goal of invention is achieved by comparator (K2) using very low comparison voltage (Uv) by means of switching call current in close proximity of zero level transition after detection of user's line current (I) using current recognition circuit (S). EFFECT: elimination of false recognition of user's line. 1 dwg
