DETECTING FAULTS IN SUBSCRIBER TELEPHONE LINES

A method tests a subscriber line. The method includes providing a classifier to predict a performance characteristic of the line based at least in part on a value of an auxiliary variable. Each value of the auxiliary variable represents a property of the line. The method also includes performing electrical measurements on the subscriber line, using the measurements to predict a value of the auxiliary variable, and predicting the performance characteristic of the line. The act of predicting the characteristic applies the classifier to the predicted value of auxiliary variable.