| 摘要 |
PURPOSE:To attain a representative line block at night with simple constitution by connecting a representative line block circuit to a night transfer device and using a subscriber source switching contact in the circuit as a contact for a circuit transfer device. CONSTITUTION:When the reception job of an attendant board at daytime is finished and the job is transferred to the night job, an NT switch equipped with the attendant board ATT is operated and a trunk line transfer relay T is restored. Then (t) and (tx) contacts are restored. Since a part shown in dotted lines in Fig. is connected in advance in the night transfer device inserted to the trunk line having the oldest number in this case, a ground potential E is given to the trunk line of the oldest number. This is received by the line circuit of a station and the corresponding representative trunk line is blocked through a succeeding discriminating processing. Thus, the representative line blocking is performed without requiring any special mounting space. |
