| 摘要 |
PURPOSE:To attain the test of an exchange depending on the practical operation by connecting a telephone set to an exchange to be tested normally and switching the connection to an exchange in operation as required so as to continue the exchange service at a fault of the exchange to be tested. CONSTITUTION:An extension telephone set 1 is connected to a private branch of exchange 8 in operation and an exchange to be tested via a line switching circuit 7. The line switching circuit 7 connects a line 11 to the exchange 9 to be tested via an interface circuit 3 by a changeover switch 2 normally (at test) and the exchange 9 to be tested is subject to the actual operating test through outgoing/incoming call of the extension 1. If the exchange 9 to be tested is faulty, an outgoing call to a station 10 or an incoming call from the station 10 takes place, the line switching device 7 switches the line 11 by using a switching controller 6 to the private branch of exchange 8 in operation and allows the exchange to execute the extension telephone set 1. |
