Method for measuring a load impedance (ZL) of a load circuit which is connected to an SLIC circuit (6) of an analog terminal connection of a terminal device, having the following steps: specifically a digital toll signal (x1) is generated by means of a Codec circuit (13) connected to the SLIC circuit (6), said toll signal (x1) being converted into an analog toll signal; the analog toll signal is output by the SLIC circuit (6) to the load circuit; an analog voltage which is brought about at the terminal connection (4,5) of the terminal device of the SLIC circuit (6) via the analog toll signal is sensed; the digital toll signal (x1) is filtered by means of an adaptive filter (39) which is provided in the Codec circuit (13) and has adjustable filter coefficients (g1, g2) for generating a filtered digital comparison signal (yv) which is converted into an analog comparison voltage (Uv); the filter coefficients (g1, g2) of the adaptive filter (39) are adjusted until the analog comparison voltage (Uv) and the analog voltage (UL), brought about by the analog toll signal, at the terminal connection (4, 5) of the terminal device are the same; the complex load impedance (ZL) of the load circuit is calculated as a function of the set filter coefficients (g1, g2)