Abstract: When an incoming call directed to an extension terminal arrives from an external telephone terminal and the incoming call signal is transferred to a voice mail unit, a voice message detection section of the voice mail unit detects the presence or absence of a voice message from the caller before the extension terminal is notified that recording of the voice message from the caller is started. When the voice message from the caller is detected, a central control section informs the extension terminal that the voice message is detected.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.

Abstract: According to this invention, a digital key telephone system connected to an analog public network NW having a function of transmitting a ringing signal including identification information of a calling line through a subscriber line (CO line), accommodating a plurality of extension lines each connected to a digital key telephone (DKT) 2 or a standard telephone (STT) 4 as an extension terminal, and having a function of switching and connecting the subscriber line to the plurality of extension lines or the extension lines to each other includes a called party storage means storing, in advance, information representing the correlation between the calling line and the extension terminals 2 and 4 as a called terminal. When a ringing signal arrives from the analog communication network NW, calling line identification information (caller ID) contained in the ringing signal is detected by a calling line identification information interface unit (RCIU) 12.