| 摘要 |
PURPOSE:To easily receive a service by providing a trunk line for transmitting a number information receiving register, a number receiving completion signal and a response signal from a public network and connecting between a private branch exchange (PBX) which cannot directly receive the number information transfer service and the trunk line by an exclusively used line. CONSTITUTION:At the time of receiving a calling signal IR from the public network CO by the central office line trunk, a primary response signal is transmitted, at the same time, the register is trapped to receive the number information and this number information is received by the register. When the PBX receives the number information, it transmits the receiving completion signal to the public network CO, and in the public network CO, a calling sound RBT is transmitted to the calling subscriber of the public network CO by the receiving of the receiving completion signal. When an extension subscriber of the PBX responds, a secondary response signal is transmitted from the central office line trunk to the public network CO to move to the service state to the subscriber of the public network. Thereby, the PBX which cannot receive the number information transfer service from the public network CO can also easily receive this service.
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