| 摘要 |
A communication terminal is coupled to a communication network via transmitting and receiving signal lines (100, 101) and a switching system. The communication terminal includes a power input line (117, 219) coupled to the transmitting and receiving signal lines, a power sink (118) for supplying power, a switch (SW) coupled between the power input line and the power sink, a hook switch (HS1) coupled between the power input line and the power sink in parallel to the switch, a detection circuit (1) coupled to the receiving signal line for detecting a signal on the receiving signal line, a state maintaining circuit (2) coupled to the switch and the detection circuit for closing the switch and for maintaining the switch in a closed state by carrying out a state maintaining operation when a signal is detected by the detection circuit, and a prohibit circuit (3) coupled to the detection circuit for prohibiting a signal detection of the detection circuit. |
