A subscriber circuit, provided with a feeding circuit for feeding the current of a call to a terminal through a subscriber line and a switching circuit group for connecting the feeding circuit to the subscriber line and releasing the feeding circuit from the subscriber line, for controlling feeding to the terminal, comprising: said feeding circuit monitoring the state of a loop of the subscriber line, converting a two-wire signal sent from the terminal into a signal predetermined coefficient-fold, and supplying the same; a level converter, connected to the subscriber line through said switching circuit group, for converting a two-wire signal sent from the terminal into a signal any coefficient-fold and supplying the same, separately from said feeding circuit; and a signal monitor for monitoring a signal, using one of an output signal of said feeding circuit and an output signal of said level converter, according to upper control information and the output of monitoring the loop of said feeding circuit, and supplying signal monitor information.