| 摘要 |
PURPOSE:To omit the switching unit in front of the central office trunk and thus to realize an economical night main wire switching system. CONSTITUTION:In the daytime mode the terminating from main wire CL is detected through central office trunk TRK with the answer given through the attendant board. And connection line (1) is set to channel network SW, and extension telephone EX can have the communication with CL. Then the night mode is obtained through operation of switch TS, and this operation is detected by scanner SCN. Based on this information, the central control unit gives the switch control within trunk TRK so that CL may be connected directly to network SW after the talking is over with CL and specific extension telephone EX. At the same time, connection line 1 is set at network SW. Thus the call of CL passes through trunk TRK to reach main telephone EX to secure the answer. In such constitution, the conventional switching unit can be omitted. |
