| 摘要 |
A telephone terminal device in connection with an office line, comprises: (a) an office line acquisition unit for acquiring the office line; (b) an office line acquisition controller responsive to a call signal sent through the office line, for driving the office line acquisition unit by call signal power; and a power supply unit responsive to DC power supplied through the office line acquired by the office line acquisition unit, for supplying the supplied DC power to the telephone terminal device as device driving power. The telephone terminal device utilizes DC power supplied from a telephone exchange office through a telephone line so that built-in backup batteries are consumed at the lowest possible consumption rate. |
