Image Number 4 for United States Patent #5150400.
A method for controlling a data terminal equipment coupled to a network via a line and coupled to a center apparatus via the line and the network. A plurality of tone signals sent from the center apparatus and having mutually different frequencies are received. The levels of the tone signals are detected. The characteristic of the line is judged on the basis of the levels of the tone signals. A suitable equalizing characteristic most suitable for the characteristic of the line is selected from among a plurality of predetermined equalizing characteristics compensating for possible characteristics of the line. There is also provided a data terminal equipment using the above-mentioned method.