Abstract:
A communication system including a plurality of terminals; and a switchboard connected to the terminals, includes a means for causing each of the terminals to register an identifier and an address of the terminal itself in the switchboard; a means for, when one of the terminals transmits a request of transmitting a list of the terminals connected to the switchboard, causing the switchboard to transmit the list of the terminals to the terminal that transmits the request; a means for, when the terminal that transmits the request selects one of the terminals from the list and transmits the identifier of the selected terminal to the switchboard, causing the switchboard to transmit the address of the selected terminal to the terminal that transmits the request; and a means for causing the terminal that transmits the request to establish a communication with the selected terminal using the received address and a default port number.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of U.S. patent application Ser. No. 11/963,475, filed on Dec. 21, 2007, which claims priority from Japanese Patent Application No. 2006-349591, filed on Dec. 26, 2006, the disclosures of which are incorporated herein in their entirety by this reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a communication system including a plurality of terminals and a switchboard connected to the terminals, and a communication method for the communication system. 
         [0004]    2. Description of the Related Art 
         [0005]    Recently, communication means have diversified. Not only conventionally known voice communication but also various communication means such as video communication, character communication (e.g., mail communication, instant message communication, and chat communication), file sharing communication, whiteboard sharing communication, and application sharing communication have been used as the communication means. Furthermore, a “peer-to-peer (P2P)” model in which terminals directly communicate with each other to exchange terminal information has been on the rise to replace a “server-client model” in which the communication means controls information (such as positions (addresses), communication capabilities and the like of terminals) on terminals such as a switchboard and a server at one location in a centralized manner. 
         [0006]    Communication software compliant with the P2P model (hereinafter, “P2P communication software”) has spread widely because of its convenience and its high functional improvement speed. P2P communication related techniques are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2003-348244, 2004-046419, 2004-304666, 2004-320289, 2004-320629, and 2006-020048. 
         [0007]    Generally, requirements to support the various communication means are high even for a switchboard designed to be compliant with the server-client model. However, a functional improvement speed of switchboard software is disadvantageously and unavoidably lower than that of P2P model communication software since it is necessary to secure sufficient design and evaluation periods so as to prevent an influence on existing switchboard functions. 
         [0008]    Meanwhile, both the switchboard software and the P2P communication software tend to adopt LAN lines using an IP network as a main communication pathway, which provides an environment that facilitates cooperation between the both software. 
       SUMMARY OF THE INVENTION 
       [0009]    It is, therefore, an object of the present invention to easily mount various new communication means in a switchboard compliant with a server-client model by interlocking the switchboard (or switchboard software) with general-purpose communication software compliant with a P2P model by simple mechanism. 
         [0010]    According to a first aspect of the present invention, there is provided a communication system including a plurality of terminals; and a switchboard connected to the terminals, comprising: means for causing each of the terminals to register an identifier and an address of the terminal itself in the switchboard; means for, when one of the terminals transmits a request of transmitting a list of the terminals connected to the switchboard, causing the switchboard to transmit the list of the terminals to the terminal that transmits the request; means for, when the terminal that transmits the request selects one of the terminals from the list and transmits the identifier of the selected terminal to the switchboard, causing the switchboard to transmit the address of the selected terminal to the terminal that transmits the request; and means for causing the terminal that transmits the request to establish a communication with the selected terminal using the received address and a default port number. 
         [0011]    According to a second aspect of the present invention, there is provided a communication system including a plurality of terminals; and a switchboard connected to the terminals, comprising: means for causing each of the terminals to register an identifier and an address of the terminal itself and a port number corresponding to each communication type in the switchboard; means for, when one of the terminals transmits a request of transmitting a list of the terminals connected to the switchboard, causing the switchboard to transmit the list of the terminals to the terminal that transmits the request; means for, when the terminal that transmits the request selects one of the terminals from the list and transmits the identifier of the selected terminal and the communication type to the switchboard, causing the switchboard to transmit the address of the selected terminal and the port number corresponding to the communication type of the selected terminal to the terminal that transmits the request; and means for causing the terminal that transmits the request to establish a communication with the selected terminal using the received address and the received port number. 
         [0012]    According to a third aspect of the present invention, there is provided a communication system including a plurality of terminals, the terminals including a first terminal and a second terminal; and a switchboard connected to the terminals, comprising: means for causing each of the terminals to register an identifier and an address of the terminal itself and a port number corresponding to each communication type in the switchboard; means for causing the first terminal to inquire the switchboard about a possible communication method, the address, and the port number of the second terminal while the first terminal is holding a voice communication with the second terminal; means for causing the switchboard to transmit the possible communication method, the address, and the port number of the second terminal to the first terminal; and means for causing the first terminal to establish a communication with the second terminal using the address and the port number received from the switchboard by a communication method included in the possible communication method received from the switchboard. 
         [0013]    According to a fourth aspect of the present invention, there is provided a communication system including a plurality of terminals, the terminals including a first terminal, a second terminal, and a third terminal; and a switchboard connected to the terminals, comprising: means for causing each of the terminals to register an identifier and an address of the terminal itself and a port number corresponding to each communication type in the switchboard; means for causing the first terminal to inquire the switchboard about a possible communication method, the address, and the port number of the third terminal equal in user to the second terminal while the first terminal is holding a voice communication with the second terminal; means for causing the switchboard to transmit the possible communication method, the address, and the port number of the third terminal to the first terminal; and means for causing the first terminal to establish a communication with the third terminal using the address and the port number received from the switchboard by a communication method included in the possible communication method received from the switchboard. 
         [0014]    The communication system according to the fourth aspect of the present invention may further comprise: means for detecting that a communication (or the voice communication) between the first terminal and the second terminal is finished; and means for finishing the communication between the first terminal and the third terminal if the communication between the first terminal and the second terminal is finished. 
         [0015]    According to a fifth aspect of the present invention, there is provided a communication system comprising: means for registering a LAN line terminal in a switchboard; means for causing a voice terminal to start a voice conference communication; means for receiving a video communication start instruction from a video terminal of a user; means for causing the video terminal to acquire information on all conference communication partners with which the voice terminal holds the communication based on user IDs received from the switchboard; means for causing the video terminal to accept a user&#39;s selection of a communication partner from a list of the conference communication partners; and means for causing switchboard terminal software of the video terminal to transmit an address of a communication partner for a video communication with which the voice terminal is holding a voice communication until the video communication with all the conference communication partners holding the video communication is established, and for causing video communication software of the video terminal to establish the video communication with the communication partner of the voice terminal. 
         [0016]    According to the present invention, various communication means can be easily added to a voice terminal of a switchboard by using existing P2P communication software. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a block diagram showing an overall configuration of a communication system according to first to sixth embodiments of the present invention; 
           [0018]      FIG. 2  is a block diagram showing a voice and video terminal shown in  FIG. 1 ; 
           [0019]      FIG. 3  is a block diagram showing a configuration of a switchboard shown in  FIG. 1 ; 
           [0020]      FIG. 4  is a block diagram showing an internal configuration of a memory shown in  FIG. 2 ; 
           [0021]      FIG. 5  is a schematic diagram showing an exemplary configuration of a database shown in  FIG. 3 ; 
           [0022]      FIG. 6  is a schematic diagram showing user setting data for terminal software shown in  FIG. 2 ; 
           [0023]      FIG. 7  is a flowchart showing operation performed by the communication system according to a first embodiment of the present invention; 
           [0024]      FIG. 8  is a flowchart showing operation performed by a communication system according to a second embodiment of the present invention; 
           [0025]      FIG. 9  is a flowchart showing operation performed by the communication system according to a third embodiment of the present invention; 
           [0026]      FIG. 10  is a flowchart showing operation performed by the communication system according to a fourth embodiment of the present invention; 
           [0027]      FIG. 11  is a flowchart showing operation performed by the communication system according to a fifth embodiment of the present invention; and 
           [0028]      FIG. 12  is a flowchart showing operation performed by the communication system according to a sixth embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Preferred embodiments of the present invention will be described hereinafter in detail with reference to the accompanying drawings. 
       First Embodiment 
       [0030]    A communication system according to a first embodiment of the present invention starts a communication by causing a switchboard to transmit information on addresses of switchboard terminals other than a switchboard terminal of the switchboard, and the switchboard terminal that has received the addresses to select a communication partner from among the switchboard terminals at the received addresses, and to pass the address of the selected switchboard terminal to independent general-purpose P2P communication software incorporated in the switchboard terminal. 
         [0031]    Furthermore, while the switchboard terminal is holding a voice communication, a communication starts by passing address information on a voice output destination to the general-purpose communication software. 
         [0032]    If the switchboard terminal separates from the P2P general-purpose communication software and differs in address, a communication starts by registering information for coupling them with each other in the switchboard and passing the information to the switchboard terminal in response to a request from the switchboard terminal. 
         [0033]    Moreover, if the switchboard terminal is holding a voice conference, a communication starts by passing address information on a voice conference partner to the switchboard terminal. 
         [0034]    A configuration of the communication system using voice lines (i.e., an internal voice line and an external voice line) and a LAN line in an office as shown in  FIG. 1  will be described. It is assumed that a communication method realized by the P2P communication software is a video communication. 
         [0035]    In the office, a voice switchboard  101  (hereinafter, simply “switchboard”) switching voice communication, a voice and video terminal  102  used by a user A and connected to a LAN line, a voice and video terminal  103  used by a user B and connected to the LAN line, a video terminal  104  used by a user C and connected to the LAN line, a voice terminal  107  connected to a voice internal line, a voice terminal  105  used by a user D and connected to the LAN line, a video terminal  106  connected to the LAN line, a CTI (Computer Telephony Integration) server  109  connected to the switchboard  101  and realizing CTI, and a presence server  110  managing and notifying status information (presence) of the terminals  102  to  107  are present. 
         [0036]    Further, the switchboard  101  is connected to a voice communication network  108  via a voice external line. 
         [0037]    In this way, the switchboard  101  is connected to the voice communication network  108  and the terminals  102  to  107 , and controls connection of voice communications held by the terminals  102  to  107 . 
         [0038]    The CTI server  109  mediates a communication between CTI client software mounted in each of the terminals  102  to  106  connected to the LAN line and the switchboard  101 . 
         [0039]    The presence server  110  communicates with the switchboard  101  and the terminals  102  to  106  connected to the LAN line, constantly updates and holds the status information (presences) of the terminals  102  to  107 , and transmits a notification to each of the terminals  102  to  106  and the switchboard  101  in response to a request. 
         [0040]    Referring now to  FIG. 2 , operations performed by respective constituent elements of each of the terminals  102  to  107  will be outlined. A user interface (“I/F”)  201  receives input signals from a keyboard, a mouse or the like and outputs video signals to a display. A voice source I/F  202  transmits and receives voice data to and from a voice source  208  connected to the voice source I/F  202 . A voice internal line I/F  203  transmits and receives signals to and from the voice communication line. A LAN line I/F  204  transmits and receives signals to and from the LAN line. A CPU  205  controls entirety of the terminal. A memory  206  is used as a work area when software or data necessary to control the terminal is used. A terminal software  211  is software stored in the memory  206  and executed by the CPU  205 . A video I/F  209  receives signals input from a video camera  210  connected to the video I/F  209 . 
         [0041]    Referring to  FIG. 3 , operations performed by respective constituent elements of the switchboard  101  will be outlined. A voice internal line I/F  301  transmits and receives signals to and from the voice communication line. A LAN line I/F  302  transmits and receives signals to and from the LAN line. A voice external line I/F  303  transmits and receives signals to and from the voice external line. A CPU  304  controls entirety of the switchboard  101 . A memory  305  is used as a work area when software or data necessary to control the switchboard  101  is used. A database  306  is an area for holding various setting data stored in the memory  305 . 
         [0042]      FIG. 4  is a schematic diagram showing a module configuration of software  211  stored in the memory  206  in each of the voice and video terminals  102  and  103 . Switchboard terminal software  402  and video communication software  408  are application software operating on an OS (Operating System)  401 . 
         [0043]    The switchboard terminal software  402  is constituted by various software modules. A switchboard I/F  403  controls communication with the switchboard  101 . A voice communication control unit  404  controls voice signal communication by communicating with the voice source I/F  202 , the voice internal line I/F  203 , and the LAN line I/F  204 . A CTI server I/F  405  controls communication with the CTI server  109  by communicating with the LAN line I/F  204 . A presence server I/F  406  controls communication with the presence server  110  by communicating with the LAN line I/F  204 . User setting data  407  stores therein a user ID and a password of the user of the terminal, information on a current communication partner and the like. 
         [0044]    The video communication software  408  is a general-purpose P2P communication software and has a video communication capability to start communication between the terminals in which the video communication software is mounted, to transmit and receive video data, and to perform a communication end processing in the first embodiment. The video communication software  408  includes a function of receiving address information on a communication partner, i.e., the other software mounted in the same terminal, and starting a communication with the partner according to the address information. 
         [0045]      FIG. 5  shows an example of contents of the database  306  stored in the memory  305  of the switchboard  101 . In a “switchboard user ID” area  501 , ID information on each of the users using the switchboard  101  is stored. In a “switchboard user password” area  502 , a password corresponding to the user ID is stored. In a “possible communication method: address: port” area  503 , a possible communication method of the terminal used by each user, an address of the terminal, and a port number used by the communication method in the terminal are stored. If the terminal supports a plurality of communication methods, a plurality of information is stored in the “possible communication method: address: port” area  503 . In a “communication partner user ID” area  504 , a user ID or an external line number of a communication partner is stored if the user is holding a communication. In an “external line” area  505 , the number of each voice external line connected to the switchboard  101  is stored. In a “communication partner number” area  506 , a telephone number of the communication partner on a voice external line having the external line number is stored. 
         [0046]      FIG. 6  shows an example of contents of the terminal software  211  stored in the memory  206  of each of the voice and video terminals  102  and  103 . In a “switchboard user ID” area  601 , a switchboard user ID of a user using the terminal  102  or  103  is stored. In a “switchboard user password” area  602 , a password corresponding to the user ID is stored. In a “possible communication method: address: port” area  603 , a possible communicate method of the terminal, the address of the terminal, and the port number used by the communication method in the terminal are stored. If the terminal supports a plurality of communication methods, a plurality of information is stored per user ID. If the terminal is connected to the voice line, an internal line number is stored in place of the address and the port number. A “communication partner” area  604  is an area in which information on the communication partner is stored during a voice or video communication of the terminal. Namely, in the “communication partner” area  604 , a user ID, an address, and a port number of the communication partner are stored. If the communication partner is a terminal that does not include a LAN line I/F and that is connected to the voice line or a terminal that is connected to the voice external line, an internal line number or an external line number is stored in the “communication partner” area  604  in place of the address, and the port number of the communication partner. In a “communication destination port initial value” area  605 , a default destination port used if the communication port of the communication partner is unknown for every communication method is stored. 
         [0047]    Operation according to the first embodiment will be described. 
         [0048]    First, an instance in which the user A starts a video communication with the user B while the user A is not on the phone will be described with reference to the flowchart of  FIG. 7 . 
         [0049]    It is assumed herein that only the address and the port for the voice communication are stored in the “possible communication method: address: port” area  603  in the terminal software  211  stored in the memory  206  of each of the voice and video terminals  102  and  103 . It is also assumed that the terminal configuration of each of the voice and video terminals  102  and  103  is such that the voice internal line I/F  203  is not present in the configuration of the voice and video terminal shown in  FIG. 2 . 
         [0050]    First, the user A input a user ID and a password using the keyboard and display  207  of the voice and video terminal  102 . In response to the input, the CPU  205  and the switchboard terminal software  402  operating in the memory  206  receive information on the user ID and the password of the user A via the user I/F  201  and the OS  401 , respectively. Further, the input user ID is stored in the “switchboard user ID” area  601  and the password is stored in the “switchboard user password” area  602 . The user ID and the password as well as the information stored in the “possible communication method: address: port” area  603  of the voice and video terminal  102  are passed to the OS  401  via the switchboard I/F  403 , and transmitted to the switchboard  101  via the LAN I/F  204 . When receiving the information via the LAN line I/F  302 , the switchboard  101  searches the received user ID from the areas  501  in the database  306 , and checks whether the password stored in the area  502  corresponding to the hit area  501  is identical with the received password. If the switchboard  101  confirms that the both passwords are identical, the switchboard  101  stores the received information of “possible communication method: address: port” in the corresponding area  503 . Likewise, the user B registers the voice and video terminal  103  in the switchboard  101  (step  701 ). 
         [0051]    The user A performs an operation for calling a video communication partner list using the keyboard and display  207  of the voice and video terminal  102 . In response to the operation, a user list disclosure request is passed from the switchboard terminal software  402  to the OS  401  via the switchboard I/F  403 , and transmitted to the switchboard  101  via the LAN I/F  204 . When receiving the information via the LAN line I/F  302 , the switchboard  101  extracts all the information stored in “switchboard user ID” areas  501  and “possible communication method: address: port” areas  503  corresponding to all the users in the database  306  included in the switchboard  101 , and transmits the information to the voice and video terminal  102 . The switchboard I/F  403  of the switchboard terminal software  402  in the voice and video terminal  102  receives the information via the LAN line I/F  204  and the OS  401 , and the voice and video terminal  102  displays the information on the display  207  via the user I/F  201  (step  702 ). 
         [0052]    The user A performs an operation for selecting the video communication partner using the keyboard and display  207  of the voice and video terminal  102 . In response to the operation, the user ID of the selected video communication partner is passed from the switchboard terminal software  402  to the OS  401  via the switchboard I/F  403 , and transmitted to the switchboard  101  via the LAN line I/F  204 . When receiving the information via the LAN line I/F  302 , the switchboard  101  searches the received user ID from the “switchboard user ID” areas  501  in the database  306  of the switchboard  101 , extracts information described in the “possible communication method: address: port” area  503  corresponding to the hit record (area  501 ), and transmits the extracted information to the voice and video terminal  102 . The switchboard I/F  403  of the switchboard terminal software  402  in the voice and video terminal  102  receives the information via the LAN line I/F  204  and the OS  401  (step  703 ). 
         [0053]    The switchboard terminal software  402  checks the received possible communication method, address, and port to confirm whether video communication is present in the area  603 . In the first embodiment, since the address and the port for the video communication are not described in the area  603 , the switchboard terminal software  402  extracts only the address for the voice communication, extracts a video communication port (Port 101 ) described in the “communication destination port initial value” area  605  as the port, and passes the address and the port to the video communication software  408 . At the same time, the switchboard terminal software  402  writes contents of the information in the “communication partner” area  604  in the user setting data  211  as video communication partner information (step  704 ). 
         [0054]    The video communication software  408  starts a video communication by setting the received address and port as the communication destination (step  705 ). 
         [0055]    In the first embodiment, it is assumed that only the address and the port for the voice communication are stored in the “possible communication method: address: port” area  603  in the terminal software  211  stored in the memory  206  of each of the voice and video terminals  102  and  103 . Alternatively, not only the address and the port for the voice communication but also the address and the port for the video communication may be stored in the “possible communication method: address: port” area  603 . 
         [0056]    In this alternative, the user A can confirm whether the communication partner is a video-communicable terminal in advance at the step  703 . Moreover, at the step  704 , the switchboard terminal software  402  passes the address and the port for the video communication among the information of the possible communication method, address, and port received from the switchboard  101  to the video communication software  408 . It is thereby possible for the terminal  102  to flexibly set the video communication port. 
         [0057]    Furthermore, in the first embodiment, the P2P communication software has been described while taking that for the video communication as an example. However, as long as the software enables communication only by receiving the address and the port, the software is not limited to the video communication software. By changing the video communication software  408  to arbitrary P2P communication software, the present invention is applicable to various communication methods such as mail communication, instant message communication, file sharing communication, whiteboard sharing communication, and application sharing communication. 
       Second Embodiment 
       [0058]    A second embodiment of the present invention will be described. 
         [0059]    In the first embodiment, it is necessary for each user to manually select the video communication partner by operating the terminal of the user. However, during a conversation, the communication partner may be automatically selected so as to be able to start a video communication. 
         [0060]    An instance of automatically selecting the communication partner will be described with reference to the flowchart of  FIG. 8 . 
         [0061]    It is assumed herein that the address and the port for the voice communication and those for the video communication are stored in the “possible communication method: address: port” area  603  of each of the voice and video terminals  102  and  103 . 
         [0062]    A step  801  is the same as the step  701  according to the first embodiment. 
         [0063]    The voice and video terminal  102  transmits signals to the voice and video terminal  103  using the voice internal line, thereby establishing a voice communication. At this time, the address and the communication method (voice communication) of the voice signal destination (i.e., the terminal of the voice communication partner) are stored in the “communication partner” area  604  in the user setting data  211 . Further, the switchboard software  402  writes the user ID of the communication partner in the “communication partner user ID” area  504  corresponding to each user in the database  306  of the switchboard  101  (step  802 ). 
         [0064]    The user A performs an operation for staring a video communication with the current voice communication partner using the keyboard and display  207  of the voice and video terminal  102 . In response to the operation, a current communication partner information request is passed from the switchboard terminal software  402  to the OS  401  via the switchboard I/F  403 , and transmitted to the switchboard  101  via the LAN line I/F  204 . When receiving the current communication partner information request via the LAN line I/F  302 , the switchboard  101  reads information described in the “communication partner user ID” area  504  corresponding to the user A in the database  306 , and searches the “switchboard user ID” area  501  corresponding to the user ID described in the area  504 . Further, the switchboard  101  extracts the possible communication method, address, and port from the “possible communication method: address: port” area  503  corresponding to the hit area  501 , and transmits the extracted information to the voice and video terminal  102 . The switchboard I/F  403  of the switchboard terminal software  402  of the voice and video terminal  102  receives the information via the LAN line I/F  204  and the OS  401  (step  803 ). 
         [0065]    The switchboard terminal software  402  checks the received possible communication method, address, and port, and confirms whether the video communication is present in the “possible communication method: address: port” area  503 . If the video communication is present, the switchboard terminal software  402  passes the address and the port for the video communication to the video communication software  408 , and at the same time, writes contents of the address and the port for the video communication in the “communication partner” area  604  in the user setting data  211  stored in the voice and video terminal  102  as the video communication partner information (step  804 ). 
         [0066]    The video communication software  408  starts a video communication while setting the received address and port as the communication destination (step  805 ). 
         [0067]    In the second embodiment, the switchboard  101  is inquired about the communication partner information at the step  803 . Alternatively, if the communication partner information stored in the terminal  102  is used, there is no need to inquire the switchboard  101  about the communication partner information. 
         [0068]    In this alternative, the switchboard terminal software  402  reads the information described in the “communication partner” area  604  in the user setting data  211  at the step  803 . The switchboard terminal software  402  passes the address and the port described in the area  604  to the video communication software  408  at the step  804 . It is thereby possible to control the video communication without using the switchboard  101  at all. 
       Third Embodiment 
       [0069]    A third embodiment of the present invention will be described. 
         [0070]    In the preceding first and second embodiments, the voice terminal is identical with the video terminal and the voice and video terminals have the same address. However, the video terminal and the voice and video terminals may be different terminals. 
         [0071]    An instance in which the video terminal and the voice and video terminals are different will be described with reference to the flowchart of  FIG. 9 . 
         [0072]    It is assumed herein that the address and the port for the video communication are stored in the “possible communication method: address: port” area  603  of each of the video terminals  104  and  106 , that the address and the port for the voice communication are stored in the “possible communication method: address: port” area  603  of the video terminal  105 , and that the “possible communication method: address: port” area  603  of the voice terminal  107  is blank. It is also assumed that the internal line number of the voice terminal  107  is set in the “possible communication method: address: port” area  503  corresponding to the user C described in the “user ID area”  501  of the database  306  of the switchboard  101 , as the address for the voice communication in advance, and that no port is described in the same “possible communication method: address: port” area  503 . It is further assumed that the voice terminal  107  is already activated and on standby. 
         [0073]    Moreover, it is assumed that the terminal configuration of each of the video terminals  104  and  106  is such that the voice internal line I/F  203  and the voice source I/F  202  are not present in the configuration of the voice and video terminal shown in  FIG. 2 , the terminal configuration of the voice terminal  105  is such that the voice internal line I/F  203  and the video I/F  209  are not present in the configuration of the voice and video terminal shown in  FIG. 2 , and that the terminal configuration of the voice terminal  107  is such that the video I/F  209  and the LAN line I/F  204  are not present in the configuration of the voice and video terminal shown in  FIG. 2 . 
         [0074]    First, the user C registers the video terminal  104  and the voice terminal  107  in the switchboard  101 , and the user D registers the voice terminal  105  and the video terminal  106  in the switchboard  101  using their respective user IDs and passwords, respectively through procedures similar to that of the step  701  in the first embodiment (step  901 ). 
         [0075]    The voice terminal  107  transmits signals to the voice terminal  105  using the voice internal line, thereby establishing a voice communication. At this time, the address and the communication method (voice communication) of the voice signal destination (i.e., the terminal of the voice communication partner) are stored in the “communication partner” area  604  in the user setting data  211  stored in the terminal  107 . Further, the switchboard software  402  writes the user ID of the communication partner in the “communication partner user ID” area  504  corresponding to each of the users C and D in the database  306  of the switchboard  101  when establishing the voice communication between them (step  902 ). 
         [0076]    The user C performs an operation for staring a video communication with the current voice communication partner using the keyboard and display  207  of the voice and video terminal  104  (step  903 ). 
         [0077]    In response to the operation, the switchboard terminal software  402  passes a current communication partner information request to the OS  401  via the switchboard I/F  403 , and the current communication partner information request is transmitted to the switchboard  101  via the LAN line I/F  204 . When receiving the current communication partner information request via the LAN line I/F  302 , the switchboard  101  reads information described in the “communication partner user ID” area  504  corresponding to the user C in the database  306 , and searches the “switchboard user ID” area  501  corresponding to the user ID described in the area  504 . Further, the switchboard  101  extracts the possible communication method, address, and port from the “possible communication method: address: port” area  503  corresponding to the hit area  501 , and transmits the extracted information to the video terminal  104 . The switchboard I/F  403  of the switchboard terminal software  402  of the video terminal  104  receives the information via the LAN line I/F  204  and the OS  401  (step  904 ). 
         [0078]    The switchboard terminal software  402  checks the received possible communication method, address, and port, and confirms whether the video communication is present in the “possible communication method: address: port” area  503 . If the video communication is present, the switchboard terminal software  402  passes the address and the port for the video communication to the video communication software  408 , and at the same time, writes contents of the address and the port for the video communication in the “communication partner” area  604  in the user setting data  211  stored in the video terminal  104  as the video communication partner information (step  905 ). 
         [0079]    The video communication software  408  starts a video communication while setting the received address and port as the communication destination (step  906 ). 
       Fourth Embodiment 
       [0080]    A fourth embodiment of the present invention will be described. 
         [0081]    In the preceding first to third embodiments, the address and the port of the communication partner are passed to the video communication software  408  at the start of the video communication, and the video communication software  408  is entrusted with the subsequent video communication control. Due to this, even if the voice communication is finished, the user is forced to manually instruct the video communication software  408  for the video communication. Alternatively, the switchboard terminal software  402  may detect end of the voice communication using the CTI server I/F  405 , and instruct the video communication software  408  to finish a video communication, thereby automatically finishing the video communication simultaneously with the end of the voice communication. 
         [0082]    An instance of automatically finishing the video communication simultaneously with the end of the voice communication using the CTI server I/F  405  will be described with reference to the flowchart of  FIG. 10 . 
         [0083]    It is assumed herein that the switchboard terminal software  402  of the video terminal  104  is connected to the CTI server  109  via the CTI server I/F  405  and that the voice terminal  107  is registered as a CTI control target. It is also assumed that the CTI server  109  acquires a status (presence) of the voice terminal  107  by communicating with the voice switchboard  101  and transmits the status information to the CTI server I/F  405  of the video terminal  104 . Further, it is assumed that all the procedures at the steps  901  to  906  are already carried out. 
         [0084]    First, a voice communication between the voice terminal  107  of the user C and the voice terminal  105  of the user D is finished (step  1001 ). 
         [0085]    The switchboard  101  notifies the CTI server  109  of the end of the voice communication between the voice terminals  105  and  107  via the LAN line I/F  302  simultaneously with the end of the voice communication. The CTI server  109  notifies the CTI server I/F  405  of the video terminal  104  that the voice terminal  107  finishes the voice communication (step  1002 ). 
         [0086]    The switchboard terminal software  402  of the video terminal  104  reads video communication partner information from the “communication partner” area  604  corresponding to the user C in the user setting data  211 , deletes the information from the area  604 , and then passes a video communication end instruction as well as the information to the video communication software  408  (step  1003 ). 
         [0087]    The video communication software  408  finishes the video communication for which the received address and port are set as the communication destination (step  1004 ). 
       Fifth Embodiment 
       [0088]    A fifth embodiment of the present invention will be described. 
         [0089]    In the fourth embodiment, the switchboard terminal software  402  detects the end of the voice communication by using the CTI server I/F  405 . Alternatively, the switchboard terminal software  402  may detect the end of the voice communication using the presence server I/F  406 , and instruct the video communication software  408  to finish a video communication, thereby automatically finishing the video communication simultaneously with the end of the voice communication. 
         [0090]    An instance of automatically finishing the video communication simultaneously with the end of the voice communication using the presence server I/F  406  will be described with reference to the flowchart of  FIG. 11 . 
         [0091]    It is assumed herein that the switchboard terminal software  402  of the video terminal  104  is connected to the presence server  110  via the presence server I/F  406  and that the voice terminal  107  is registered as a presence watching target. It is also assumed that the presence server  110  acquires a status (presence) of the voice terminal  107  by communicating with the switchboard  101  and transmits the status information to the presence server I/F  406  of the video terminal  104 . Further, it is assumed that all the procedures at the steps  901  to  906  are already carried out. 
         [0092]    First, a voice communication between the voice terminal  107  of the user C and the voice terminal  105  of the user D is finished (step  1101 ). 
         [0093]    The switchboard  101  notifies the presence server  110  that the presence of the voice terminal  107  changes from a state of holding a voice communication to a standby state, via the LAN line I/F  302  simultaneously with the end of the voice communication. The presence server  110  notifies the presence server I/F  406  of the video terminal  104  that the voice terminal  107  finishes the voice communication (step  1102 ). 
         [0094]    The switchboard terminal software  402  of the video terminal  104  regards the information as the end of the voice communication, reads video communication partner information from the “communication partner” area  604  corresponding to the user C in the user setting data  211 , deletes the information from the area  604 , and then passes a video communication end instruction as well as the information to the video communication software  408  (step  1103 ). 
         [0095]    The video communication software  408  finishes the video communication for which the received address and port are set as the communication destination (step  1104 ). 
       Sixth Embodiment 
       [0096]    In the preceding first to fifth embodiments, one-to-one voice or video communication is held. Alternatively, a video conference communication may be held by interlocking the voice or video communication with a voice conference by a plurality of terminals. 
         [0097]    An instance of holding a video conference communication will be described with reference to the flowchart of  FIG. 12 . 
         [0098]    It is assumed herein that the address and the port for the voice communication and the address and the port for the video communication are stored in the “possible communication method: address: port” area  603  of the voice and video terminal  102 , that the address and the port for the video communication are stored in the “possible communication method: address: port” area  603  of each of the video terminals  104  and  106 , that the address and the port for the voice communication are stored in the “possible communication method: address: port” area  603  of the voice terminal  105 , and that the “possible communication method: address: port” area  603  of the voice terminal  107  is blank. It is also assumed that the internal line number of the voice terminal  107  is set in the “possible communication method: address: port” area  503  corresponding to the user C described in the “user ID area”  501  of the database  306  of the switchboard  101 , as the address for the voice communication in advance, and that no port is described in the same “possible communication method: address: port” area  503 . It is further assumed that the voice terminal  107  is already activated and on standby. Further, it is assumed that the video communication software  408  can simultaneously hold video communications with a plurality of communication partners. 
         [0099]    Moreover, it is assumed that the terminal configuration of each of the video terminals  104  and  106  is such that the voice internal line I/F  203  and the voice source I/F  202  are not present in the configuration of the voice and video terminal shown in  FIG. 2 , the terminal configuration of the voice terminal  105  is such that the voice internal line I/F  203  and the video I/F  209  are not present in the configuration of the voice and video terminal shown in  FIG. 2 , and that the terminal configuration of the voice terminal  107  is such that the video I/F  209  and the LAN line I/F  204  are not present in the configuration of the voice and video terminal shown in  FIG. 2 . 
         [0100]    First, the user A registers the voice and video terminal  102 , the user C registers the video terminal  104  and the voice terminal  107 , and the user D registers the voice terminal  105  and the video terminal  106  in the switchboard  101  using their respective user IDs and passwords, respectively through procedures similar to that of the step  701  in the first embodiment (step  1201 ). 
         [0101]    A conference communication is established among the voice and video terminal  102 , the voice terminal  107 , and the voice terminal  105 . At this time, the addresses and the communication methods (voice communication) of the voice signal destinations (i.e., the terminals of the voice communication partners) are stored in the “communication partner” area  604  in the user setting data  211  in each of the terminals  102 ,  105 , and  107 . Further, the switchboard software  402  of each of the terminals  102 ,  105 , and  107  writes the user IDs of the communication partners in the “communication partner user ID” area  504  corresponding to each of the users A, C, and D in the database  306  of the switchboard  101  when the conference communication is held among them (step  1202 ). 
         [0102]    The user C performs an operation for staring a video communication with the current voice communication partners using the keyboard and display  207  of the voice and video terminal  104  (step  1203 ). 
         [0103]    In response to the operation, the switchboard terminal software  402  of the voice and video terminal  104  passes a current communication partner information request to the OS  401  via the switchboard I/F  403 , and the current communication partner information request is transmitted to the switchboard  101  via the LAN line I/F  204 . When receiving the current communication partner information request via the LAN line I/F  302 , the switchboard  101  reads information described in the “communication partner user ID” area  504  corresponding to the user C in the database  306 , and searches a plurality of “switchboard user ID” areas  501  corresponding to the user IDs described in the areas  504 , respectively. Further, the switchboard  101  extracts the possible communication methods, addresses, and ports from the “possible communication method: address: port” areas  503  corresponding to the hit plural areas  501 , and transmits all the extracted information as well as the user IDs to the video terminal  104 . 
         [0104]    The switchboard I/F  403  of the switchboard terminal software  402  of the video terminal  104  receives the information via the LAN line I/F  204  and the OS  401  (step  1204 ). 
         [0105]    The switchboard terminal software  402  checks all the received possible communication methods, addresses, and ports, and confirms whether the video communication is present in each of the “possible communication method: address: port” areas  503 . If the video communication is present in each of the “possible communication method: address: port” areas  503 , the switchboard terminal software  402  displays the user IDs of a plurality of video-communicable video communication partner candidates on the display  207  via the user I/F  201 . Thereafter, the user C performs an operation for selecting an arbitrary video communication partner from among the displayed user IDs using the keyboard and display  207  of the video terminal  104  (step  1205 ). 
         [0106]    In response to the selection operation, the switchboard terminal software  402  passes the address and the port of the selected user ID for the video communication to the video communication software  408 , and at the same time, writes contents of the address and the port for the video communication in the “communication partner” area  604  in the user setting data  604  stored in the video terminal  104  as the video communication partner information (step  1206 ). 
         [0107]    The video communication software  408  starts a video communication while setting the received address and port as the communication destination (step  1207 ). 
         [0108]    The user C can additionally perform the operation for selecting a video communication partner from among the displayed user IDs using the keyboard and display  207  of the video terminal  104  if the user wants to hold a video communication with another user. In this case, the procedures at the steps  1206  to  1208  are repeatedly carried out whenever the selection operation is performed (step  1208 ). 
         [0109]    Although the exemplary embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and alternatives can be made therein without departing from the sprit and scope of the invention as defined by the appended claims. Further, it is the inventor&#39;s intent to retain all equivalents of the claimed invention even if the claims are amended during prosecution.