Abstract: The object is to realize a multi-line service with proprietary messages/procedures only between telephone apparatuses such as IP telephones, and to use a connection management server complying with a standard connection protocol without using proprietary messages/procedures between the connection management server such as the SIP server and the telephone apparatus. A telephone apparatus for performing a telephone call using a predetermined communication protocol and a connection protocol, includes: a unit configured to mutually report a line status using a proprietary interface different from the connection protocol between the telephone apparatus and another telephone apparatus forming a multi-line group.

Abstract: In a voice data communication system comprising a switchboard for switching lines, a network, interworking units for interworking a protocol on the network with a protocol for a line switching, and IP extension terminals connected to the interworking units through the network, a switchboard notifies a communication between interworking units to the interworking units when recognizing the communication between the interworking units, which are provided corresponding to each of IP extension terminals, and establish a relay route to the interworking unit according to a notification from the switchboard and establish a voice data packet route to a route between the IP extension terminals through the network by using the relay route in response to a route establishment request from the IP extension terminals accommodated, or when the interworking unit is a single and the notification is received from the switchboard, establish a voice data packet route to a route between the IP extension terminals through the netw

Abstract: In a voice data communication system comprising a switchboard for switching lines, a network, interworking units for interworking a protocol on the network with a protocol for a line switching, and IP extension terminals connected to the interworking units through the network, a switchboard notifies a communication between interworking units to the interworking units when recognizing the communication between the interworking units, which are provided corresponding to each of IP extension terminals, and establish a relay route to the interworking unit according to a notification from the switchboard and establish a voice data packet route to a route between the IP extension terminals through the network by using the relay route in response to a route establishment request from the IP extension terminals accommodated, or when the interworking unit is a single and the notification is received from the switchboard, establish a voice data packet route to a route between the IP extension terminals through the netw