PURPOSE: To provide the exchange system in which a damage of noise is suppressed in a message waiting state display.

CONSTITUTION: In the private branch of exchange system having a message center function in which an extension terminal 1 using a standard telephone set incorporated with a lamp is accommodated via an extension connection line 1a, a lamp lighting drive power supply output and a ringer ringing power supply output are fed from a private branch of exchange 2 to the extension terminal 1 via the extension connection line 1a when a message to be transferred to the user of the extension terminal is in existence and a message waiting state is displayed by executing the lamp lighting and ringer ringing of the extension terminal 1 connecting to the extension connection line 1a, circuit switching means 1b, 1c switched in interlocking with the switching of a main breaker switching the power of a room where the extension terminal 1 is installed are connected in series with the extension connection line 1a of the extension terminal to switch the line.