| 摘要 |
When, in order to convey an advice or the like to an operator from a supervisor, a two-party telephone communication connection state between a customer terminal connected to an outside line (3) side of a private branch exchange and an operator terminal (10) is changed to a three-party telephone communication connection state among the outside line (3), the operator terminal (10) and the supervisor terminal (20) by use of a conference trunk (52) provided in the private branch exchange, the three-party telephone communication connection state is established by connecting a transmission line (31) of the outside line (3), a first transmission line (11) that is one of two transmission lines provided to the operator terminal (10), a reception line (13) also provided to the operator terminal (10), a transmission line (21) of the supervisor terminal (20) and a reception line (22) of the supervisor terminal (20) to any conference trunk (52) that is captured from unused-state conference trunks and further by connecting a second transmission line (12), which is the other of the two transmission lines of the operator terminal (10), to a reception line (32) of the outside line (3). |
