Teleconference system

A teleconference system by which a reservation for use can be readily and certainly established. The teleconference system includes an input unit for inputting image data and audio data; an output unit for outputting image data and audio data; a communication unit for multiplexing the image data and the audio data; a reservation management unit for controlling a reservation time at which the teleconference system is used and for allowing a reservation partner to use the teleconference system when the reservation time has come; and an interface unit for connecting with an external device. The reservation management unit performs a reservation control of a teleconference system based on reservation information sent from the external device via the interface unit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a teleconference system where attendants 
can hold a conference together with attendants who are at a remote 
location with the help of video screens, loudspeakers or the like, and 
more particularly to a teleconference system that can accept a reservation 
for the use thereof. 
2. Related Background Art 
FIG. 8 is a block diagram showing the configuration of a conventional 
teleconference system. A codec circuit 14 is connected to a camera 10 for 
taking the image of an attendant, a microphone 11 receives the voice of an 
attendant, a monitor 12 displays the image of an opposite attendant, and a 
loudspeaker 13 for reproduces the voice of an opposite attendant. The 
codec circuit 14 also compresses an image signal from the camera 10 and an 
audio signal from the microphone 11, expands the compressed image signal 
and the compressed audio signal from an opposite teleconference system 17, 
and outputs the results to the monitor 12 and the loudspeaker 13, 
respectively. The codec circuit 14 is connected to a terminal adaptor 15 
which is connected to the opposite teleconference system 17 via a 
conventional circuit 16. The terminal adaptor 15 also performs an 
interfacing process between the codec circuit 14 and the conventional 
circuit 16. 
In such a conventional teleconference system, the codec circuit 14 receives 
the image of an attendant taken by the camera 10 and the voice of the 
attendant gathered by the microphone 11. The terminal adaptor 15 outputs 
the compressed data to the opposite teleconference system 17 at a remote 
place via the conventional circuit 16. The codec circuit 14 receives the 
compressed image signal and audio signal of the opposite attendant which 
are input to the terminal adaptor 15 via the conventional circuit 16. Then 
to expanded image signal is displayed on the monitor 12. The expanded 
audio signal is output to the loudspeaker 13. The opposite teleconference 
system 17 receives the image signal and the audio signal mentioned above 
to expand them. The image signal is displayed on the monitor 12 and the 
audio signal is output to the loudspeaker 13. 
In the conventional teleconference system, information such as dial 
numbers, addresses and comments of plural communication partners are 
pre-registered. When the teleconference system is used, the menu including 
line numbers related to registration is displayed Selecting a specific 
communication partner in the menu allows an automatic originating call 
based on the selected line number. 
However, the teleconference system cannot make a reservation for a use 
thereof. For example, a partner cannot sometimes use the teleconference 
system at a desired time if another partner makes a line connection 
immediately before the partner wants to use the teleconference system. 
In order to cope with the problem, it may be considered of course to 
prepare a reservation function to the teleconference system. 
However, there is a disadvantage in that a reservation cannot be made for 
the teleconference system in the case where there is no time to go to the 
teleconference system installing spot for a reservation registration, or 
there is no person to ask for a reservation registration because a 
schedule is very tight until the date and time desired to use the 
teleconference system. 
Also there is a disadvantage in that even if a partner tries to make a 
reservation registration, the teleconference system cannot be used at his 
reservation time because of an interruption from another teleconference 
system. 
Moreover, because the completion time of a reserved conference is unclear 
to the attendants, the teleconference system is sometimes switched to 
another reservation partner before a conclusion of a subject at the 
conference comes to an end. 
SUMMARY OF THE INVENTION 
In order to overcome the above mentioned various problems, an object of the 
present invention is to provide a teleconference system by which a 
reservation for use can be readily and certainly made thus being easy to 
use. 
Another object of the present invention is to provide a teleconference 
system where a teleconference can be reserved by an external device 
connected via an interface, whereby a reservation registration can be made 
from a remote location without coming to the spot where the teleconference 
system is installed. 
Still another object of the present invention is to provide a 
teleconference system that allows a reservation partner to use certainly 
the system at a reservation time, by inhibiting other partners other than 
a reservation partner from using the system when the reservation time has 
arrived. 
It is another object of the present invention to provide a teleconference 
system that can be effectively utilized by allowing other partners to use 
the system when the reservation partner does not use the reservation in a 
predetermined period of time after the reservation time. 
Further, it is another object of the present invention to provide a 
teleconference system in which communication preparations can be made to 
execute an automatic line connection at a predetermined date and time or 
to execute a line connection with one touch operation. 
A still further object of the present invention is to provide a 
teleconference system where an attendant can manage the progress of a 
conference call by informing other attendants of the remaining usable 
period of the teleconference system. 
These and the other objects of the present invention will become apparent 
from the following drawing and detailed description take in connection 
with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
First Embodiment 
An explanation will be given below for an embodiment according to the 
present invention with reference to the attached drawings. FIG. 1 is a 
block diagram showing the configuration of the present embodiment. Like 
numerals are attached to like elements previously described with respect 
to FIG. 8. 
According to the present embodiment, as shown in FIG. 1, a controller 18, a 
memory device 19, an alarm signal generator 20 and an alarm signal adder 
21 are added to the teleconference system shown in previously described 
FIG. 8. The controller 18 is connected to a general line 16, a terminal 
adaptor 15, the codec circuit 14 and the alarm signal generator 20. In the 
present embodiment, the terminal device 22 is connected to the controller 
18, together with a general line such as and integrated services digital 
network (ISDN) or a local line such as a local area network (LAN). The 
alarm signal adder 21 is connected to the alarm signal generator 20, the 
monitor 21, the loudspeaker 13, and the codec circuit 14. 
The memory device 19 stores a use schedule table (reservation table) of the 
teleconference system. The controller 18 monitors the operations of the 
codec circuit 14 and the terminal adaptor 15. The controller 18 also 
rewrites the reservation table in the memory device 19 based on a request 
from the terminal device 22 on reservation registration, reservation 
retrieving, and cancellation of the teleconference system, and provides to 
the alarm signal generator 20 an alarm signal indicating that the 
following reservation time is drawing near. The alarm signal generator 20 
produces an alarm signal in response to an alarm signal from the 
controller 18. The alarm signal adder 21 convolves a message indicating an 
approach of the following reservation time to an image signal and an audio 
signal output from the codec circuit 14 in response to an alarm signal to 
output the result to the monitor 12 and the loudspeaker 13. 
The operation of the present embodiment will be described below. The basic 
operation of the teleconference system according to the present embodiment 
resembles the conventional teleconference system. A unique operation of 
the present embodiment will be described below. 
Conference Reservation 
A reservation partner for the teleconference system first uses a telephone 
to a controller 18' of a teleconference system at a desired remote 
location via the terminal device 22 to request the data transmission of a 
reservation table. In response to the request, the controller 18' 
transmits the reservation table of the teleconference system read out of a 
memory device 19' to transmit the data in the reservation table to the 
terminal device 22. The controller 18 of the teleconference system is 
connected to the teleconference system of the reservation partner via the 
local line such as LAN. The terminal device 22 also requests the 
controller 18 of the teleconference system to transmit data on the 
reservation table via a local line such as LAN. The controller 18 
transmits data in the reservation table of the teleconference system read 
out of the memory device 19 to the terminal device 22 on the requesting 
side via the local line. The controller 18' and the memory device 19' are 
arranged in the teleconference system 17. 
The terminal device 22 of the reservation partner displays both the 
schedule table sent from the remote teleconference system and the schedule 
table sent from the teleconference system connected to the local line on 
the monitor screen, and selects as a teleconference time a desired date, 
time and time period from unscheduled dates and time periods. The terminal 
device 22 inputs data including the selected use date, time, time period, 
and the reservation partner's name and section. 
The controller 18' of each teleconference system receives the 
teleconference reservation message sent from the terminal device 22 and 
additionally stores the same to the schedule table stored in the memory 
device 19'. Then the memory device 19' transmits a reservation completion 
message to the terminal device 22. The reservation partner confirms the 
completed reservation by the return message to select a completion 
command, thus disconnecting the line from the controller 18' to complete 
the reservation procedure. 
Alarm Time Setting 
Before starting a conference, the user of the teleconference system sets an 
alarm producing time to a time preceding a reservation completion time. In 
particular, the codec circuit 14 provides a reservation table data request 
signal to the controller 18. The controller 18 outputs that data on the 
reservation table read out of the memory device 19 in response to the 
request signal to the codec circuit 14. The codec circuit 14 sends the 
data on the reservation table to the monitor 12 via the alarm signal adder 
21 to display it on the monitor 12. At this time, since the alarm signal 
generator 20 does not output an alarm signal, both the image signal and 
the audio signal from the codec circuit 14 are respectively manifested on 
the monitor 12 and by the loudspeaker 13 without any change. 
The user of the teleconference system confirms a conference completion time 
with reference to the data on the reservation table displayed on the 
monitor 12, thus setting an alarm operation time. The codec circuit 14 
sends the input alarm operation time to the controller 18 for storage in 
an internal memory area of the controller 18. 
Alarm Operation 
The controller 18 compares the current time with the alarm operation time 
stored in the internal memory area. When the current time corresponds to 
the alarm operation time, the controller 18 outputs an alarm command 
signal to the alarm signal generator 20 which outputs it to the alarm 
signal adder 21. In response to the alarm signal, the alarm signal adder 
21 convolves the image signal and the audio signal from the codec circuit 
14 with a message warning about the approach of the following reservation 
time to output the result to the monitor 12 and the loudspeaker 13. For 
example, a message saying "The remaining time for the conference is 30 
minutes" is on the lower portion of the screen of the monitor 12 while the 
loudspeaker 13 produces an alarm sound such as a chime. 
The teleconference system 17 includes the codec circuit 14, the alarm 
signal generator 20, and the alarm signal adder 21. When the controller 18 
recognizes that the alarm operation time has arrived, it informs the 
teleconference system 17 of that fact. This process allows the 
teleconference system 17 to produce the message display and alarm sound. 
Since the chairperson hears the alarm sound and confirms the message on 
the monitor 12, he can adjust the progress of the conference so as to 
finish in the remaining time, thus effectively holding the conference in a 
scheduled period of time. 
For the embodiment, a description has been given for the case where a 
general line is linked to both the controller 18 and the terminal device 
22. However, it is possible to connect the general line only to the 
terminal device 22. In this case, a reservation partner of the 
teleconference system makes a telephone call from his terminal device 22 
to the terminal device of a partner in charge at a remote location to 
arrange in advance the open time of the remote teleconference system. Each 
partner in charge accesses the controller of each teleconference system to 
call the teleconference system reservation table. Then he selects a 
desired time from the unscheduled time period on the reservation table to 
make a teleconference system reservation. 
In this state, the data of the retrieved reservation table, which are 
interchanged between the terminals, are shared by reservation partners and 
a partner in charge. They can compare and study the reservation schedule 
table to schedule the teleconference, by telephone to an open date and 
time which is a common unscheduled reservation date and time, thus 
registering a final reservation to each teleconference system. In this 
case, the date and time of the teleconference can be determined while the 
content of the reservation schedule table at hand is confirmed through a 
telephone line, without interchanging data on the reservation schedule 
table between the reservation partner and a partner in charge. 
As described above, the present embodiment can provide a simple reservation 
for the teleconference system via a terminal device coupled to the general 
line and the LAN. The teleconference can be certainly held at a desired 
date and time because the alarm signal generator produces an alarm signal 
at a preset warning time. 
The teleconference can be adjusted in progress and effectively held because 
a dispatch on the teleconference system is made to the self terminal and 
the opposite terminals based on the alarm signal and the attendants of the 
teleconference are informed of the remaining time of the conference. When 
there are plural subjects for discussion, a time setting can be made to 
each subject by different alarms. 
Second Embodiment 
Next the teleconference system according to the second embodiment will be 
described which can reserve a teleconference with a simpler operation and 
inhibit partners other than a reservation partner from using the same at a 
scheduled date. 
FIG. 2 is a block diagram showing the general configuration of the 
teleconference system according to the second embodiment. 
A television camera 101 acts as image data input means to take an image of 
attendants. A monitor 102 displays the image data sent from the opposite 
terminal. A video codec 103 encodes image data taken by the television 
camera 101 to compress it and decodes the compressed image data to expand 
it. Numeral 104 represents a microphone and 105 represents a loudspeaker. 
The audio codec 106 decodes and compresses audio data received by the 
microphone 104 and expands by demultiplexing the compressed audio data. 
The audio codec 106 acts as a system controller to control the entire 
system. 
A liquid crystal display 108 displays operational data. A console unit 109 
inputs reservation information and manipulates operational commands. A 
multiplexer and demultiplexer 110 multiplexes and demultiplexes image 
data, audio date and data from a system controller 107. A reservation 
registration management unit 111 registers and controls the reservations 
for conferences. A timer 112 measures time. A LAN interface unit 113 
communicates with other communication terminal devices such as personal 
computer 115 or another teleconference system via a local area network 
(hereinafter referred to LAN). 
Furthermore, the multiplexer and demultiplexer 110 is coupled to an 
integrated services digital network (ISDN) via a line interface unit 114 
which is coupled to the other teleconference systems. The reservation 
registration management unit 111 includes a reservation registration file 
F1 to register ID data of reservation partners, reservation dates 
(hereinafter referred to reservation period), and reservation partner's 
line numbers. 
Next, the teleconference system according to the second embodiment will be 
described below with reference to FIG. 2. The video codec 103 encodes and 
compresses image data from the television camera 101. The audio codec 106 
encodes and compresses audio data form the microphone 104. The multiplexer 
and demultiplexer 110 multiplexes the coded and compressed data as well as 
the data from the system controller 107 to transmit the result to a 
communication partner via the line interface unit 114. 
In similar manner, a line interface unit 114 separates multiplexed data 
sent from a destination partner into image data and audio data encoded in 
the multiplexer and demultiplexer unit 110. The image codec 103 decodes 
the image data for display on the monitor 102. The audio codec 106 decodes 
the audio data for produce an audio sound from the loudspeaker 105. 
The system controller 107 is connected to the external line via the line 
interface unit 114 to perform a data communication to a communication 
partner via the multiplexer and demultiplexer unit 110. The user of the 
teleconference system uses the liquid crystal display 108 and the console 
unit 109 to perform the user's ID data input and line connection and 
disconnection, thus making the reservation registrations. 
Next, a description will be made for the reservation registration operation 
in accordance with the flow chart shown in FIG. 3. 
The reservation registration management unit 111 processes various 
reservation registrations under control of the system controller 107. That 
is, the reservation registration management unit 111 receives a 
registration command from the console unit 109 of the self teleconference 
system and another communication terminal 115, together with a reservation 
applicant's ID data, a communication partner's line number and a 
reservation date and time (reservation period) (step S1). Thus the 
reservation registration management unit 111 refers to the reservation 
registration field F1 to judge whether the self device as well as the 
input related communication partner are in an empty state at the input 
reservation date and time (step S2). Questioning automatically to the 
opposite communication partner enables obtaining of the reservation state 
thereof. 
As a result, if the self device and the input related opposite 
communication partner's device are empty at an input reservation date and 
time, the reservation content related to an application is additionally 
registered to the reservation registration file F1 (step S3). The fact 
that the registration has been completed is informed to the registration 
applicant to output on the self display (step S4). The process returns to 
the main flow after the reservation contents are transmitted to all the 
teleconference devices in the entire system (step S5). Each teleconference 
device which receives the registration content performs an addition 
registration to the reservation registration field F1 of the self deice. 
All updated reservation conditions in the system are registered in real 
time in the reservation registration fields F1 of all teleconference 
devices in the entire system. 
If either the self device or the opposite communication partner's device is 
in a reserved state at an input reservation date, the content of the 
reservation registration field F1 is transmitted to the communication 
terminal device (including teleconference device) of the reservation 
applicant (step S6). Since the device on the reservation applicant side 
displays the received content of the reservation registration field F1, 
the reservation applicant can immediately re-order another empty date and 
time (period) or can re-order after another reservation date is agreed to 
by the opposite communication partner via a telephone line. When the 
re-order is immediately made with the line connected, it is necessary to 
input only a changed date but the ID data is input. 
It is judged whether a re-order has been made in a predetermined period of 
time (step S7). If there has been a re-order in a predetermined period of 
time, it is judged whether both the self device and the opposite 
communication partner's device are empty at the reservation date (step 
S8). As a result, if both the devices are empty, the flow advances to the 
step S3 to perform a registration process. On the other hand, if it is 
judged that either one of the devices is not empty, error information is 
transmitted to the reservation applicant's device to display (step S9) and 
then the process returns to the step S7. In the step S7, if there is no 
re-order in a predetermined period of time, the process returns to the 
main flow. 
Next, a description will be made for the reservation time management 
operation based on the flow chart shown in FIG. 4. 
The system controller 107 judges whether the self device includes the 
reservations of which reservation dates have arrived according to the 
reservation registration field F1 and the timer 112 (step S21). As a 
result, if no corresponding reservations are found, the process returns to 
the main flow without any change. If the corresponding reservations are 
found, it is judged whether there are the externally connected lines (step 
S22). As a result, if there is a line connected to an external device, it 
is judged whether the external device is a reserved opposite communication 
party of which the reservation date is imminent (step S23). As a result, 
if the external device is the opposite communication partner's device 
which is related to the reservation date, the television camera 101 and 
the monitor 102 of the self device initiated for the teleconference (step 
S24). Then the process returns to the main flow. On the other hand, if the 
external device is not the opposite communication partner's device of 
which is related to the coming reservation date, it is informed that the 
system is in a reserved state so that the line is disconnected (step S25). 
Then the process returns to the main flow. 
When it is judged that there is no line externally connected, it is judged 
whether ID data from the console unit 109 in the self device had been 
input (step S26). As a result, when there is no ID data input from the 
self device, the process returns to the main flow without any change. When 
there is ID data input from the self device, it is judged whether there is 
ID data corresponding to the reservation of which the reservation date has 
arrived (step S27). As a result, if there is ID data corresponding to the 
reservation of which the reservation date has arrived, the process goes to 
the step S24 to initiate the television camera 101 and the monitor 102 in 
the self device. On the other had, if there is no ID data corresponding to 
the reservation of which the reservation date has arrived, the display 108 
displays that the system is in a reserved state (step S28) so that the 
process returns to the main flow. 
According to the present embodiment, a reservation can be very conveniently 
made by a remote device via a LAN, without going to the location where a 
teleconference system is installed to make a reservation. If a user's ID 
data and an opposite communication partner's line number are reserved and 
registered, other communication partners can be inhibited from using the 
system during the reserved period of time, whereby only reservation 
partners can certainly use the teleconference system. 
Third Embodiment 
Next a description will be given for the third embodiment which can 
automatically prepare a conference when a reservation date has arrived. 
The third embodiment will be described with reference to FIGS. 5 to 7. 
FIG. 5 is a block diagram showing the general configuration of the 
teleconference system according to the embodiment. Since the third 
embodiment is substantially similar to the second embodiment, the 
differences between them will be briefly described. 
That is, the LAN interface unit 113 and the reservation registration 
management unit 111 in the second embodiment are not found in the third 
embodiment. However a hard disk 116 is newly added to store the 
registration of communication destination information and the use 
reservation data of the teleconference system. The hard disk 116 stores 
communication destination information file F2 including the line numbers, 
addresses and comments of communication destinations and the conference 
document file F3 including conference material data used in 
teleconferences, in addition to the reservation registration information 
file F1 in the second embodiment. Only the persons, which are authorized 
for utilization and of which the line numbers is recorded to the initial 
of the conference document file F3, can access the conference material F3. 
Next the general operation of the teleconference system according to the 
third embodiment will be described based on the flow chart shown in FIG. 6 
When the system is activated, the system controller 107 first displays 
process items in a menu form on the display 108 (step S31). It is judged 
which menu item has been selected (step S32). As a result, when a 
communication destination information registration menu is selected, 
communication destination information such as the line number, address and 
comment of a communication destination input later is completely 
registered in the communication destination information file F2 (step 
S33). When a reservation information registration menu is selected, 
reserved partner's ID data reservation date, opposite communication 
partner or the like input later are completely registered in the 
reservation registration file F1 (step S34). When a conference material 
storage menu is selected, another process is completely performed in 
accordance with the selected menu (step S36). 
When a transmission of conference document data is requested from an 
external device, the response is made only to the line numbers as 
transmission destinations that are attached to the conference document 
file regarding the transmission request, for other line numbers which are 
not attached, whereby the secret of the conference document data is kept. 
An actual registration/storage process is performed by subjecting the 
following input content and operational content to a sequential guidance 
display in a conversational mode. When reservation information is 
registered, the contents of the reservation registration file F1 are 
displayed from beginning to end. When an empty time is selected from the 
file F1, the contents of the communication destination information file F2 
is displayed to select an opposite communication partner. Then a guidance 
display is performed so as to input a reserved applicant's ID data. When 
the reserved applicant's ID data is input, the guidance display is 
selectively performed so as to establish an automatic line connection to a 
reserved opposite communication partner or a line connection by a 
one-touch operation when a reservation time has come. When either one of 
the line connections is selected, the currently input and registered 
reservation information is transmitted to all the teleconference devices 
in the system. The registration from the self device has already been 
performed to the reservation registration file F1 in response to the 
selection and input operation. 
Next the reservation time management operation of the third embodiment is 
described based on the flow chart shown in FIG. 7. 
The system controller 107 judges whether there is a reservation of which 
the use reservation date of the self device has arrived based on the 
reservation registration file F1 and the timer 112 (step S41). As a 
result, if no reservation of which the reservation date has arrived is 
found, the process returns to the main flow shown in FIG. 6. If a 
reservation of which the reservation date has arrived is found, it is 
judged whether the reservation has been registered so as to perform an 
automatic line connection to an opposite communication partner to be 
reserved (step S42). As a result, if an automatic connection is 
registered, a line connection or an originating call is immediately 
performed without waiting for the operation of the console unit 109 (step 
43). The television camera 101 and the monitor 102 in the self device are 
activated to arrange a teleconference (step S44), and then the process 
returns to the main flow. 
On the other hand, if a one touch connection is registered instead of the 
automatic connection, it is possible to prepare a line connection to an 
opposite communication partner to be reserved in accordance with a 
one-touch operation (step S45). 
The one-touch connection, for example, is performed by outputting the line 
number of the opposite communication partner to the transmit port in the 
line interface 115. Thus it is judged whether a predetermined period of 
time (till a time in a reservation period) has passed since a reservation 
date (or the starting time of the reserved period (step S46). As a result, 
if the predetermined period has not passed, it is judged whether there is 
the one-touch operation (step S47). If there is the one-touch operation, 
the opposite communication party's line number output on the transmit port 
is transmitted to establish line connection (step S48). Then the process 
proceeds to the step S44 to activate the system. 
On the other hand, if there is no one-touch operation, it is judged whether 
there is a line connection to an external device (step S49). If there is a 
line connection to the external device, it is judged whether the external 
device is the opposite communication partner corresponding to the 
reservation of which the reservation date has arrived (step S50). As a 
result, the external device is the opposite communication partner 
corresponding to the above reservation, the process goes to the step S44 
to activate the device. On the contrary, if the external device is not the 
opposite communication partner corresponding to the above reservation, the 
line is disconnected after the external device is informed that the system 
is in a reserved state (step S51). Then the process returns to the main 
flow. In the step S49, if it is judged that no line connection from the 
external device has been established, the process returns to the step S46, 
whereby it is again judged whether a predetermined period of time has 
passed. If the predetermined period of time has passed, the forbidden use 
of the system to other partners except the reservation partner are 
released (step S52). Then the process returns to the main flow. 
In the third embodiment, when a reservation date has arrived, it is 
possible to selectively register either an automatic line connection or a 
line connection by a one-touch operation. Therefore, if the use at a 
reservation date is certain, an automatic line connection is registered, 
thus omitting problems due to the line connection. If the use at a 
reservation date is not certain, a one-touch line connection is 
registered, whereby if the device is in a usable state at the reservation 
date, the one touch operation can simplify the line connection, while if 
the device is not in a usable state at the reservation date, other 
partners except the reservation partner can use the system after a 
predetermined period of time has passed since the reservation date. 
Therefore the teleconference system according to the present invention can 
be effectively used. Since the registration such as a reservation is made 
in a conversational mode, even a person inexperienced in operation can 
simply register. Secret leaks to the third person can be presented because 
conference materials are accessible only by the persons whose line numbers 
are registered. 
The present invention should not be limited only to the above embodiments. 
The present invention, for example, can be applicable to the 
teleconference system having all the functions described in the first to 
third embodiments. 
As described above, the second and third embodiment can reserve a 
teleconference from a remote location via the LAN. This feature results in 
that it is not needed to go directly to the location of the teleconference 
device for a reservation; the teleconference can be certainly prepared in 
advance; and the teleconference line can be certainly kept by 
disconnecting the line connection from other partners other than a 
reservation partner at a reservation date. 
The present invention has various advantages. When the reservation partner 
does not use the teleconference system after a predetermined period of 
time from a reservation date, partners except the reservation partner can 
use it even in the reservation period. Moreover, there is no fear that the 
secret of conference material leaks to the third person. Therefore the 
teleconference can be held smoothly and certainly. 
As described above, the preferred embodiments according to the present 
invention has been described. However, the present invention should not be 
limited only to the above mentioned embodiments but it is possible to 
provide various modified embodiments in the scope of the present 
invention.