PURPOSE: To execute version-up of an exchange program and a control system board or the like without stopping the operation of an exchange in an active system.

CONSTITUTION: After an exchange 2 in a standby system is disconnected from an exchange 1 in an active system, the operation of the exchange 2 is stopped and a control system board is replaced or an exchange program is revised attended with the replacement, and the exchange 2 is started again. When a maintenance console 3 of the active system enters new operation data set to a database 23 in the standby system in this state, since a command control section 11 of the exchange 1 transfers the data to a data setting processing section 22 via a command control section 21 of the exchange 2, the data setting processing section 22 sets the transferred data to the database 23. Then the exchange 2 in the standby system is switched to the active system and the exchange 1 in the active system is switched to the standby system to version up the program and the control board without stopping the operation of the exchange of the active system.