| 摘要 |
PURPOSE:To detect a line break trunk during a call by counting up the contents of a line break frequency storage. means with an information signal from an extension which encounters a line break in the calling and making an alarm display when the counted value reaches a preset value. CONSTITUTION:If trouble occurs to a line connected to a trunk(TRK) 3 during the connection between the extension 1 and the TRK 3 and the line is disconnected, a central controller(CC) 5 knows the line break from the TRK 3 which is being monitored and also controls a channel switch SW 2 when the extension 1 enters the hooking state to connect the extension 1 to an originating register(OR) 4. The CC 5 counts up the line break frequency OC the TRK #1 area of a line break frequency memory ME T with information read out of a busy state memory MA 6 every time the line of the TRK 3 during calling is broken and a special dial signal is received from the opposite calling extension. The CC 5 when confirming that the line break frequency reaches the preset value sends an alarm message to a PRT 8 to print out the message. Consequently, the trunk which enters the line break state during calling is detected.
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