| 摘要 |
PURPOSE:To prevent the mis-dialing due to signal missing and to increase the quality of service, by transmitting the special signal to make ineffective the dialing of the service subscriber, when the incoming call of the third party is present while the serviced subscriber is in communication with the service center. CONSTITUTION:When the incoming serviced subscriber during communication, CWSUB, receives service from the service center SC, if incoming call is present from the third subscriber SUB, the A-C terminal of the incoming switch unit SWU during communication, is connected to the incoming unit during communication CWE. When a relay A connected to the subscriber CWSUB is operative, the contact a is closed and the signal tone OSC combining two waves of high group frequencies of the PB signal is inserted on the communication line via the coil RETO. Thus, the combination of the PB signal high group frequency and low group frequency is unbalanced, and it is processed as ineffective dial with the characteristics of the PB receiver PBREC. Further, OSC is inserted to the communication line up to the hooking operation of the subscriber CWSUB, and the PB signal from the incoming during communication to the response of the subscriber CWSUB is processed as ineffective dial at the center SC. |
