| 摘要 |
<p>A line switching device is configured in such a manner as to establish the call between an interphone device for obtaining visitor's information and a call device by being connected to the interphone device via an IP network, and connected to the call device via a telecommunication network. The line switching device is provided with a first communication unit, a second communication unit, and a line unit for controlling the first communication unit and the second communication unit. The line unit is provided with a calling section and a control section. The calling section is configured in such a manner as to create a call-back message for requesting the call device to make the call back to the interphone device using the visitor's information, and control the second communication unit to transmit the created call-back message to the call device. The control section is configured in such a manner as to establish the call between the interphone device and the call device by controlling the first communication unit and the second communication unit.</p> |
