Abstract: In a circuit for notifying ring signal reception to a wireless telephone in a wireless/wired composite telephone system having a direct-current (DC) blocking circuit for blocking a DC component from a ring signal input through a ring terminal and a tip terminal and a ring detector for adjusting output signals depending on the ring signal having frequency components, a ring detecting circuit including an optical coupler for blocking a negative portion of an inputted signal received from the ring detector and for inverting a positive portion and for outputting a signal corresponding thereto, and a filter for receiving the signal output from the optical coupler and for generating a ring detection signal.