To provide a door interphone system which can talk over a telephone among human beings P which are present in the caller V of a user's house 10 and user's parent's home 20 even if the user's house 10 is absent, and which can be prevented from it turning out that is absent, and to provide a door interphone transfer apparatus and a method of controlling it.
If the caller V comes to the user's house 10, the ringing button of a door interphone slave unit 11 is pushed. Then, a ringing control signal is formed, and is transmitted to a second door interphone transfer device 23 arranged in the parent's home 20 of the user who is forwarding destination set beforehand through a first door interphone master unit 12 and a first door interphone transfer unit 13 in the user's house 10. The ringing control signal is given from the second door interphone transfer device 23 to the second door interphone master unit 22. Consequently, a ringing sound is generated from the second door interphone master unit 22. It is received by the human being P who is present in the user's parent's home 20. Also, even if the user's house 10 is absent, it can behave so that the human being P who is present in the user's parents' home 20 may be in the user's house 10.
Tadashi Inoue
Takaaki Teiaki