| 摘要 |
PURPOSE:To delete interface circuits for extensions to the number of trunk lines below the number of the extensions by providing the digital trunk lines and the interface circuits for the extensions of the same number and a switch for connecting these trunk lines and the circuits. CONSTITUTION:In a terminal controller, the digital trunk lines 3 (3-1, 3-2) connected thereto and the interface circuits 52 for the extensions of the same number (52-1, 52-2) are only provided and the switch circuit 53 for connecting the interface circuits for the trunk lines 51 (51-1, 51-2) and a switch 56 for connecting the circuit 52 and digital extensions 6 (6-1-6-4) connected to the terminal controller are provided. Thereby, the interface circuits 52 for the digital extensions of the same number as the two line connected digital trunk lines 3 are provided and two circuits are deleted in comparison with the case provided at every digital extensions 6 connected with the four-line.
|
