| 摘要 |
PURPOSE:To make it possible for both called and calling subscribers to release a channel by taking the initiative through a switching unit, by providing subscriber's terminals with a function of preventing a subscriber from performing error hook operation in its circuit. CONSTITUTION:As the subscriber's-side method of a catchphone set, it is made possible for a called subscriber to connect with a new calling subscriber through momentary on-hook operation in order to answer to incoming from the calling subscriber while the called subscriber is engaged. After the operation of realy T1, the on-hook state of the handset is detected as an on-hook state by making use of the slow release time of realy T1, holding relay F off. For this purpose, the slow release time of this relay T1 should be longer than the total time of the continuance of the on-hook state of the subscriber using the new service and the release time of relay T0. In on-hook operation after the talk, relay T0 operates and realy T1 is released, so that the state before a ring-back tone is sent out from the switching unit will be set. |
