| 摘要 |
PURPOSE:To prevent a call reached from an incoming line from being subject to unconnection processing by registering the incoming line being an object of blocking and setting the incoming line after registration into the block state if a fault takes place. CONSTITUTION:If a fault takes place in a relay exchange 100, a fault detection section 122 in a central controller 120 detects it to extract a trunk number TN whose registration information (r) is set to logical '1' from a registration table 131. Then a fault detection section 122 sets a trunk corresponding to the trunk number TN extracted into the block state to a management table 132 and to start a block execution section 123 thereby allowing an incoming trunk 140 to send a block signal to a corresponding incoming line 200. A sender side exchange (not shown) receives a sent block signal to block the incoming line 200. The sender exchange avoids the call to the relay exchange 100 via the incoming line 200 and bypasses the call to a normal relay exchange.
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