Abstract: Method and apparatus for detecting and sectionalizing troubles on telephone lines automatically. Specifically, an embodiment for detecting and sectionalizing troubles on a telephone line connecting a switching machine and a subscriber telephone set connected thereto over the telephone line, includes apparatus which: (a) emits a pulse over the telephone line; (b) detects reflections of the pulse; and (c) and determines whether a reflection was received prior to the expiration of a predetermined time period. The predetermined period relates to a distance which is less than the length of the telephone line between the switching machine and the subscriber telephone set.