LINE SWITCHING SYSTEM

PURPOSE:To previously prevent a line from erroneous switching due to operational troubles of a switching device, etc. by performing a line test prior to switching the defective line by using a line testing device provided to a slave station and checking whether channel switching can be performed or not, by a master station. CONSTITUTION:When a trouble is generated in a transmission circuit network, a trouble detecting device 5 of a slave station 2 detects the trouble and the trouble information is sent to a master office 1 through a monitoring and controlling line 3 while being controlled by a communication controlling equipment 6 of the slave station. The master station 1 analyzes the trouble information to check the trouble line, picks up a switching command which has been previously stored for the line concerned and finds the slave station 2 relating to the switching of the trouble line. When the trouble line is separated from a line branching device 9 connected to both the ends of the channel at its end, a command for branched connection to a line testing device 10 is sent and a switching command is sent through the monitor and control line 3, a changeover switch 7 operates so that the line testing device 10 is connected to the trouble line through the line by-passing the defective transmission line. If the switching operation is not performed correctly, the test shows a defective result.