PURPOSE:To eliminate the man-hour for installing a new line by automatically switching an active line to a newly installed exchange side by means of an actuating signal issued when the newly installing exchange makes test origination and automatically performing a line opening test and voice level propriety deciding test. CONSTITUTION:When an opening test is performed from a newly installed exchange 11 to a public line side, a busy tone is generated to the exchange 11 side when the line 16 is busy by an old exchange 12 is busy or a blocking signal is automatically issued to the exchange so as to automatically control the connection and, at the same time, to automatically switch the currently used line 16 to the exchange 11 side by means of an automatic switching means 6 by using an actuating signal issued from the exchange 11 when the line 16 is not busy. Moreover, a testing outgoing signal issued from the newly installed exchange 11 side when the active line 16 is not busy is sent after attenuating the signal by a prescribed quantity by means of a loss inserting means 4 to detect the propriety of the sound level automatically. Therefore, the operating man-hour can be reduced.
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