| 摘要 |
PURPOSE:To prevent the generation of a fault even if the operation of a changeover switch is forgotten by connecting an originating control circuit of the own telephone to a subscriber telephone circuit with a non-lock key operation after the own telephone is hooked off and securing the automatic connection between an incoming detecting circuit and the subscriber telephone circuit when the own telephone is hooked on. CONSTITUTION:A call is fed to an optional subscriber telephone TEL2 from a telephone TEL1 connected between terminals TL1 and TL2. In such a case, a non-lock type key K is connected to a relay TEL within an originating control circuit SEND when the TEL1 is hooked off. Then the relay TEL works for self- support when the key K is pushed. An incoming detecting circuit DET is detached from a circuit with actuation of the relay TEL; while the circuit SEND is connected to the circuit. Then the circuit SEND is driven to transmit a dial signal to a subscriber telephone circuit via a contact cml. Thus a call is possible to the TEL2. The TEL1 is hooked on when the call is over and the relay TEL is restored. Then the circuit DET is connected again to the circuit. |
