To provide a telephone system by which caller's convenience is enhanced by effectively using a presence managing function.
A SIP (Session Initiation Protocol) server 40 manages presence information to manage whether a user is present or absent by IP telephone sets A1 to Am, and B1 to Bn. At a call request, the SIP server 40 confirms the presence information of an IP telephone set an an incoming destination and informs the IP telephone set as a calling source that the user of the IP telephone set as the incoming destination is absent in such a case. The IP telephone set having received the information displays the reception on a display unit to let the user know. Further, the SIP server discards the request to call the IP telephone set whose user is absent.
Satoshi Kono
Makoto Nakamura
Kurata Masatoshi
Takashi Mine
Yoshihiro Fukuhara
Sadao Muramatsu
Ryo Hashimoto