JPH022268A - Digital communication system - Google Patents

Abstract

PURPOSE:To suppress useless call and to improve the distribution efficiency by providing a means managing number of idle lines to a store and forward exchange and checking the presence of an idle line in the presence of the idle channel in communication channels and giving a call to a designated distribution destination without data distribution in the presence of the idle line only. CONSTITUTION:A facsimile equipment makes a call to a store and forward exchange 100 to designate multiple address transmission and stores picture information of a distribution original into a memory device of the store and forward exchange 100. When a CPU section 110 receives picture information whose distribution is commanded by multiple address, the section 110 registers a facsimile equipment being an object of multiple address transmission. Thus, a terminal equipment having a maximum terminal number is sought ad the presence of distribution control, the presence of an idle number in the belonging distribution group of the said terminal equipment and the presence of an idle channel in a communication controller 120 are checked from a control table. Then the call to the terminal equipment is commanded to the communication controller 120. Since the operation available line is grasped and the calling is managed in this way, useless calling and waiting are suppressed.

Description

[Detailed description of the invention] [Objective of the invention] (Industrial application field) The present invention is used in high-speed digital communication networks, etc., and aims to improve a storage and forwarding device for distributing the same information to multiple terminals. Regarding digital communication network systems.

(Prior art) In high-speed digital communication networks, communication terminals such as telephones, computers, and facsimile machines are connected to terminal interfaces provided independently for each terminal, and these terminal interfaces are connected to multimedia multiplexing that performs time-division multiplexing processing. At the same time, it is connected to a high-speed digital line via this multimedia multiplexing device, and a unique address is assigned to each terminal interface.The multimedia multiplexing device sequentially changes this address to connect each terminal. Each terminal device transmits or receives data when this address is its own, thereby exchanging data with the multimedia multiplexing device, and the multimedia multiplexing device at this time The divided and multiplexed data is sent to a high-speed digital line, and the received data is decomposed and when it is the communication order of the corresponding terminal address at the destination, it is transmitted and received by the terminal at that address. Take control.

By the way, conventional multimedia multiplexing devices have multiple terminal interfaces and PBXs connected to an internal data bus.
A multiplexing sub-block consisting of a terminal interface and a data bus expansion unit connected to the internal data bus, connected to a high-speed digital line and a data bus, and connected to the data bus via the data bus expansion unit. The allocated physical addresses of the terminal interfaces and PBX interfaces in the multiplexing sub-block are sequentially specified at predetermined time intervals, a time slot is assigned to each terminal device, and the time slots are used to access each terminal device. In addition to making it possible to send and receive data, time slots are used to transmit the multiplexed data obtained by this to a high-speed digital line, and to assign destination communication terminal devices for received data sent over a high-speed digital line. It consists of a multiplexing unit that performs transmission to communication terminal equipment. The data bus expansion unit is a connection unit for adding and connecting other multiplexing subblocks to the data bus.

In such a configuration, the multiplexing unit sequentially changes the physical address at predetermined time intervals to notify the current time slot, and if there is an incoming signal for that time slot, outputs 1 byte of that incoming signal onto the data bus. do. Also, if there is data sent from the terminal, it is received. Each terminal interface and PBX interface identifies whether the physical address outputted from the multiplexing unit on the data bus is assigned to itself or not, and if the address is assigned to itself, it is assigned to its own time slot. It receives the data on the data bus, and also sends out the data sent from the self-expander 1 onto the data bus. In this way, each terminal interface or PBX interface obtains access rights to the data bus when it becomes its own time slot for the time slots that are sequentially allocated, and performs communication by exchanging data.

Here, a private branch exchange (PBX) is connected to the PBX interface of the multiplexing sub-block, and an extension telephone and facsimile are connected via this PBX.

By the way, high-speed digital lines are used by users who pay a high lease fee to rent them as their own private lines from telecommunications and telephone companies, etc., and use them, for example, by forming a network between the user's main offices and branches. The total number of time slots is determined, and some specific time slots are used for facsimile communication, some specific time slots are used for computer communication, and others are used for telephone lines. According to user needs,
Build the system in advance. Communication is performed by time division multiplexing, using empty time slots for phone calls in the case of phone calls, and using empty time slots for facsimile communication in the case of facsimile communication. By the way, in recent years, in order to transmit the same document to multiple facsimile machines or to perform efficient facsimile communication, a storage and forwarding device is connected to the center's PBX, and the image signal of the document to be broadcast is transmitted from the calling facsimile machine. , is sent to this storage and forwarding device and stored in the memory of the storage and forwarding device, and the store and forwarding device attempts to make a call and if there is a free line for facsimile (that is, a free time slot for facsimile communication), it uses this. The image signal is sent sequentially to each specified facsimile using the .

In this way, conventional storage-and-forwarding devices are configured so that if there is a document to be sent, the device attempts to make a call, regardless of the availability of its own lines or the status of the other party's facsimile machine. Control was such that when the number of calls was low or when the line was busy, a call was made, and if a busy line was detected, the call was redialed after a certain period of waiting.

Then, when redialing, another channel will make a call, and if the line is in use first, it will detect that it is busy again and enter a wait period for a certain period of time. It may take a long time to finish sending the document to the other party by waiting for a wait time and then retrying. Such problems occurred.

(Problem to be solved by the invention) In this way, conventional high-speed digital communication places a multimedia multiplexing device at a service point, connects these devices with a user's dedicated line, and connects terminal devices to the multimedia multiplexing device. Telephones, facsimile machines, etc. connected via a PBX or PBX are used to transmit data through time division multiplexing using time slots assigned to each machine. Make use of it. The total number of time slots is determined, and a certain number of time slots are used for facsimile communication, a certain number of time slots are used for computer communication, and others are used for telephone lines.
Build a system in advance according to user needs. Communication is performed by time division multiplexing, using empty time slots for phone calls in the case of phone calls, and using empty time slots for facsimile communication in the case of facsimile communication. By the way, in recent years, in order to perform multicast distribution and efficient facsimile communication in which the same document is sent to multiple facsimile machines, a storage and forwarding device is connected to the center's PBX, and the image signal of the document to be broadcast is sent to the calling facsimile. Therefore, the storage and forwarding device sends the data to the storage and forwarding device and stores it in the memory of the storage and forwarding device, and the storage and forwarding device performs no management of vacant time slots for facsimile on the line connecting the multimedia multiplexing devices. When a call is made randomly and a connection is made to the other facsimile machine, the image signal is transmitted to each designated facsimile machine in sequence. In this way, conventional storage and forwarding devices If there is a document to be sent, the fax machine is configured to attempt to make a call regardless of whether the line available to it is free or the status of the other party's facsimile machine. It was controlled so that if it detected that the line was busy, it would wait for a certain amount of time and then redial. Also, when redialing, another channel will make a call, and if the line is in use first, it will detect that it is busy again and enter a wait period for a certain period of time. It may take a long time to finish sending the document to the other party by waiting for a wait time and then retrying. This is extremely inefficient, and also causes problems such as unnecessarily ending transmissions.

Therefore, the purpose of this invention is to grasp the line occupancy status and limit the number of calls, thereby suppressing unnecessary calls and improving delivery efficiency, and also suppressing the occurrence of undelivered terminations. The objective is to provide a digital communication network system that enables

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object 1, the present invention is configured as follows. That is, the multiplexing devices to which the terminals are connected are connected by a transmission path, and communications between the terminals are time-division multiplexed using time slots assigned according to the type of terminal, and
When exchanging data, the exchange data is first stored in a central storage and forwarding device that has multiple communication channels and can communicate with the other party's terminals for the number of communication channels, and then sent to the called party's terminal. On the other hand, if there is an empty time slot allocated for the data exchange at the time of the call, the data is distributed via the multiplexing device over the line using the empty time slot, and if there is no empty time slot at the time of the call, the data is distributed for a predetermined time. In a high-speed digital communication network in which distribution is attempted by re-calling after a period of time has elapsed, the storage and forwarding device includes means for managing the number of free lines allocated for the data exchange on the transmission path between the multiplexing devices. , If there is an empty channel among the communication channels, check whether there is an empty line allocated for the data transfer of the transmission path corresponding to the designated delivery destination where data is not delivered, and only if there is an empty line, the data is not delivered. The system is configured to have means for successively calling designated distribution destinations and delivering data by calling the designated distribution destinations.

(Function) In such a configuration, each multiplexing device is connected by a transmission line, and a terminal is connected to each of these multiplexing devices, and communication between the terminals of each multiplexing device via the transmission path is performed by the terminal. This is carried out by time division multiplex transmission using time slots allocated according to the type of transmission. When exchanging digital data such as facsimile communication, the exchange data is once stored in a central storage and forwarding device, and then distributed by the storage and forwarding device to a designated distribution destination. The storage and forwarding device has multiple communication channels and can communicate with as many partner terminals as the number of communication channels, but when delivering to a specified partner terminal, it calls the other party terminal and calls the other party terminal if the line is blocked. For example, after a predetermined period of time has elapsed, the call is made again and the delivery is attempted. However, this storage and forwarding device specifically manages the vacant time slots allocated for the data exchange, that is, the number of vacant lines, for transmission, and when there is a vacant channel among the communication channels, data is not delivered. The system checks whether there is an idle line on the transmission line corresponding to the specified distribution destination, and only when there is an idle line, calls are made to the specified distribution destination to which the data has not yet been distributed. In this way, the designated distribution destinations are sequentially called and data is distributed only when there is an available line, so it is possible to suppress wasteful operations such as waiting for a predetermined time and re-calling due to no available line. Not only can distribution be carried out efficiently in a short period of time, but also by repeating waiting time and re-calling due to no available lines, it is possible to avoid the situation where un-delivery ends due to exceeding the specified number of re-calls.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which the present invention is applied to a storage/forwarding device. In the figure, 100 is a storage and forwarding device, which includes a CPU section 110 that plays a central role in controlling the storage and forwarding device, a communication control device 120 that controls transmission and reception, and also stores data such as image signals and various tables. It is equipped with a memory device etc. to store the information. The communication control device 120 has a plurality of channels for communication, namely, channel ch-1, channel ch-2, -, channel c i
t - n, and a communication path can be secured for each channel, but here, as an example, n - a
This will be explained as 5. That is, the communication control device 120 controls channel ch-1, channel ch-2, -, and channel c.
h-6. Further, 201 to 203 are facsimile devices connected to and accommodated in the PBX 401, 301 to 305 are facsimile devices connected to and accommodated in the PBX 403, and 121 to 123 are facsimile devices connected to and accommodated in the PBX 401.
B X4021: A facsimile machine to be connected and accommodated. Hereinafter, the facsimile device will be referred to as FAX. 401～
403 is a private branch exchange (hereinafter referred to as PBX), and a multimedia multiplexer (hereinafter referred to as MIX) 5
Configure a network with 01 to 503 and connect the PBX
401 is FAX 201 to FAX 203, and
PBX 402 Ni;tFAX 121-FAX 1
23 and the storage and forwarding device 100, and the PBX 40
31:: connects and accommodates r'AX 301-FAX 305. Of course, in addition to this, each PBX 401 to 403
It also accommodates multiple extension telephones.

MUX 501 to MUX 503 are multimedia multiplexing devices, and the basic contents and operations thereof are as explained in the conventional example, and are similar to the above-mentioned PBXs 401 to PBX.
403 and line 601, [with i02, base and ↑
The lines that make up the wire network. Lines 601 and (i02) are high-speed digital lines that connect between MLIX 501 and MUX 502 (7) and between MUX 502 and MIX 503. (7), respectively.

Now, in order to explain the present invention with reference to FIG.
In 2002, there will be 3 lines. here,
As a communication condition, from the storage and forwarding device 100, FAX 1
21~l'AX 123, PAX 201~PAX
203, l'AX 301-I)AX 305
A description will be given of circular transmission in which the same document is distributed to a total of 11 facsimile machines at the same time. Note that since facsimile communication is most effective in the case of a center-end system in which data is always delivered to a destination terminal via a storage/forwarding device located at a center, this case will be explained as an example. Therefore, it is assumed that one of the facsimile machines makes a call to the storage and forwarding device 100 and the designation for broadcast transmission and the image information of the distributed document are stored in the memory device of the storage and forwarding device 100 in advance.

The storage/forwarding device 100 sets the channel of the communication control device to ch-
Since there are 6 channels from Ch-1 to Ch-8, and 11 facsimile machines are distributing data, in principle, under the conditions of this embodiment, if all lines for facsimile communication are open, If you perform simultaneous distribution only once, the distribution should be completed.

The following explanation will be based on this premise. First, a case where the present invention is not applied will be described. Let us consider what will happen if, for example, the storage and forwarding device 100 makes calls in order from the facsimile machines with the highest terminal numbers.

The terminal numbers are shown here in a form corresponding to the numbers such as FAX 121, +;Ax 201, etc. shown in FIG. Now, under the control of the CPU section 110, the storage/forwarding device 100 has the terminal number r305J.
r304 J, r303 J~, r12 in order
PAX 3.
Use channel ch-1 when connecting to PBX
402, MUX 502, line 602 MIX
503 After passing through PBX 403, 1'AX 30
5, one line is blocked at this connection point. At this time, the connection is established normally and communication begins. The next call to I)AX 304 is made using the next free channel, channel ch-2, and the PI3X
402, MIIX 502, line 602゜MIX
503, fax 304 via PBX 403
will be connected. Similarly, when FAX 303 is connected, all lines 602 are connected.

Then, when making a call to PAX 302, channel eh-4 is used to call PBX 402 and MIX 5.
021 line 002, MIX 503, PBX
403, but as in the above condition, only 3 lines (3 time slots) are allocated for line 602 for facsimile communication, so 3 lines are used for facsimile communication. When the line is blocked, there are no free lines left.

Therefore, the line 602 becomes "line busy",
Channel ch-4 enters wait.

Similarly, if you try to call PAX 301, line 6
At 02, it becomes "4 line busy" and channel ch-5 also enters the wait state.

:(7) 1&, the call is made to PAX 203, but in this case, channel ch-6, which is the last free channel, is used. Soshite PBX 402, MIX 502,
The line 601 will be connected to the TEFAX 203 through the MLIX 501 and PBX 401, and at this point the line 6ol will be blocked. At this time, the connection is normal and image signals can be distributed.

At this point, all six communication channels of the communication control device 120 are blocked, so the first call is terminated. In this state, FAX 305 to PAX 30 including weight
1 and FAX 203 were called (
(See Figure 4).

Next, when channel ch-1 finishes the first distribution and becomes vacant, the communication control device 120 is not called for a while.
Since we will be calling a facsimile machine after AX 202, first, we will call the FA using the empty channel ch-1.
Make a call to X202. And in this case, PBX 40
2, MIX 502, line 001, MIX
501.

It connects to the FAX 202 via the PBX 401 and communicates with it.

Similarly, when channel ah-2 becomes vacant after the first communication, communication control device 120 makes a call to FAX 201 using channel eh-2. And in this case,
PI3X 402, MtlX 502, Line Go
t, MUX 501.

It connects to the FAX 201 via the PBX 401 and communicates with it.

Similarly, when channel ch-3 ends the first communication and becomes vacant, communication control device 120 makes a call to PAX 123 using channel ah-3. Then, P13X 402 connects the extension PAX 123 and performs delivery, but channels ch-4 and ch-5 are removed from the "line busy" wait, and then FAX 301 is called again. PI3X 402
, MIX 502.

Line 802, MUX 503, PBX 403
Connect to TeFAX 302 and PAX 301 via
connect. And channel ch-G is I'AX 12
2 via PBX 402.

At this point, since there are no more free channels, the second call also ends (see FIG. 4). However, at the end of the communication due to the second call, no delivery was made to PAX 121, and the message was sent via PBX 402 using channel c11-1, which became vacant at the end of the second communication. If you do not call and connect for the third time, you will not be able to deliver to PAX 121, and the delivery that should have been completed in two calls will take an extra one time (see Figure 4). ).

Figure 2 shows storage and forwarding device 1 when using the method of the present invention.
3 is a flowchart showing the control operation in the 020 section 110 that constitutes the 00. Figure 3 shows the control table used for the control operation, and shows the facsimile terminal (
facsimile machine) table. Terminal number section T30
stores the numbers assigned to each facsimile machine, as described above. 'r31 is a distribution control registration unit that registers the presence or absence of distribution control for each terminal, and ]32 is an affiliated distribution group registration unit, specifically, the line 601.
A group using line 602, a group using line 602,
The terminals are divided into three groups: groups that do not use either the line Got or the line 602, and each terminal registers which group it belongs to. T33 is a part for registering the number of available lines (number of allocated lines) for each distribution group, and T34 is a part for registering the current number of free lines for each distribution group. These are registered and tabulated as shown in Figure 3 under the conditions of this example, and 020 parts 110
Updates are managed by.

Now, when the 020 unit 110 receives the image information that is instructed to be distributed by broadcast, it registers the facsimile device terminals to be transmitted by broadcast, and then searches for the terminal with the highest terminal number, and searches for the terminal with the highest terminal number, and After checking the presence or absence of distribution control, the presence or absence of an idle line in the distribution group to which the terminal belongs, the presence or absence of an idle channel in the communication control device 120, etc., the communication control device 120 is instructed to make a call to the terminal.

To be more specific, the maximum terminal number at this point is r305J, and all lines and channels for facsimile communication are vacant, so the CPυ unit 110 is r'
When a request for calling and distributing a call to the AX 305 is found, the process proceeds to step s21 as shown in the flowchart of FIG.
To check whether the terminal requires distribution control, first execute PAX 3 of the terminal number in the control table in Figure 3.
Look at column 05. Then, since the delivery control item is "Yes", it is determined that the control of the present invention (hereinafter referred to as delivery control) is necessary.

Then, the process advances to step s22, and it is checked whether there is a free line available. Similarly, when looking at the column for terminal number PAX 305 in the control table in Figure 3, the column for the number of free lines is "
3", it is determined that there is an "available line", and the process proceeds to step s23, where control is performed to establish a call connection. If the call is connected, the process advances to step s24. Since one line was used due to the above call connection, step s2
In step 4, count down the number of free lines and select the distribution group "
The table T34 of vacant lines of "1" is updated to "2", and the process ends.

It should be noted that the "distribution request" to the terminal for which the distribution has been completed is canceled at that point.

Next, it learns of the distribution request for PAX 304 with the larger terminal number, and moves on to call connection processing for FAX 304 using channel ch-2, which is the next available channel.

In this case as well, the same process as described above is performed and the table T34 is updated to "1" at this time.

Next, when the call is made to terminal number r303J and communication is made with FAX 303 using channel ch-3, table T34 is similarly updated to "0".

Now, when we move on to a call connection to terminal number r302J and communicate with FAX 302 using channel ch-4, we enter step s22 and check table T34, which shows that the number of free lines is "0". . Therefore, in this case, the 020 unit 110 ends without making a call, and uses channel ch-4 again to call the next terminal number r30.
Attempts to communicate with 1J's PAX 301. At this time, the table T34 is also "0", and step s22
If this is determined by the check in , the process will end without making a call. At this stage, channel c
Since h-4 is still vacant, the 020 unit 110 uses channel ch-4 again to start communication with the PAX 203 of the next terminal number r203J that has a distribution request.

At this time as well, first execute step s21, look at the column of terminal number r2 (j3J) in the table in FIG.
In step 1, I learned that the distribution control was “white” and proceeded to step s.
22 and check for free lines. Here, we will check the number of free lines in distribution group "2" to which the terminal with terminal number r203J belongs, but since distribution group "2" is still unused, table T34 shows the number of free lines. is "2", so there is space for two lines, so proceed to step 203 and fax
Call and communicate with 203, station, Tsubu s24
The number of free lines is counted down by one and the table T34 is updated to "1". Similarly, a call connection is made to the next distribution requesting terminal, PAX 202 with terminal number r202J, using the vacant channel ch-5, and FAX 20 is sent.
Start communicating with 2. At this time, the number of free lines table T34 of "Distribution Group" will be updated to rOJ,
When the 020 unit 110 attempts to communicate with the next delivery requesting terminal, r'AX 201, using the last free channel ch-6, it is determined in step s22 that there is no free line, so the call is made to the FAX 201. Quit without doing anything. The 020 unit 110 then proceeds to step s22 again in order to allocate the vacant channel ch-6 to the next distribution requesting terminal, 17AX 123. At this time,
The terminal number r123J is PB like the storage/forwarding device 100.
It is a terminal housed in X402 and has a line (il
You can connect by extension without using 802. Therefore, the distribution control table section molecule 3 in the terminal number r123J column
1 is ``no distribution control'' and there is no need to check the line availability. Therefore, step s25
Proceed to , make a call, connect, and communicate. This completes the first call (see Figure 5).

At this time, since the CPU section 110 has used up all the channels of the communication control device 120, the next call cannot be made until any channel becomes free. In this case, the 020 unit 110 rewrites the number of available lines in table T34 to the number of usable lines in table T33 in preparation for the next call.

Now, the image information is simultaneously transmitted to the six connected facsimile terminals, and when the transmission is completed and the line is disconnected, the next distribution work begins. That is, when a call is made (2 degrees 1), the CI) 0 unit 110 searches for a terminal with a distribution request. I'AX 305, PAX 304.

Since it is sent to PAX 303 on the first call,
There is no distribution request,” and the terminals with distribution requests are FAX 302 FAX 301 PAX 201
There are PAX 122 and PAX 121. First of all, select FAX 3, which has the highest terminal number in the channel number.
02 is assigned, and the process proceeds to step s21. I"AX 3
Since the corresponding distribution control table T31 for PA
The number of free lines in the distribution group to which X 302 belongs is "3".
”, so we know that there is space, so step s
Proceed to 23. After making a call connection to the FAX 302, the process proceeds to step s24, where the number of free lines of the distribution group to which the FAX 302 belongs is set to "2", and the process ends. Similarly, the 020 unit 110 makes a call to the FAX 301 using channel ch-2. When the call connection to PAX 301 is terminated, the number of free lines in distribution group "1" to which FAX 301 belongs is "1", and there is still one free line, but the I corresponding to the distribution group of this free line is 'AX 305 to l' AX 301 have already been distributed, so "None" is displayed.
It becomes. Therefore, the distribution will move on to the terminal in the next rank, but the distribution group r 2 J (7) PAX 203, FAX 20 to which the terminal in that rank belongs
Since FAX 201 is already delivered in the first call, only FAX 201 remains in this distribution group. Therefore, channel ch-3 is sent to FAX 201.
is assigned, and the process proceeds to step s21. The subsequent operation is the same as above, and when channel ch-4 connects and communicates with FAX 122 and channel ch-5 connects with FAX 121, there are no more terminals requesting distribution, and the distribution to all terminals ends. (See Figure 5).

In this way, the multiplexing devices installed at each point are connected by a transmission path, terminals are connected to the multiplexing device, and communication between terminals between each point uses time slots assigned according to the type of terminal. When transmitting and receiving digital data that does not require immediacy, such as facsimile communication, multiple communication channels are provided to enable communication with other terminals corresponding to the number of communication channels. This exchange data is once stored in a central storage and exchange device, and when the storage and exchange device performs distribution to a designated partner terminal at another point, it makes a call to the destination terminal and uses the data allocated for the data exchange. If there is an empty time slot, the data is distributed via the multiplexing device using the line using the empty time slot, and if there is no empty time slot when a call is made, a call is made again after waiting for a predetermined time and distribution is attempted. In the digital communication network, the storage and forwarding device includes a means for managing the number of free lines allocated for the data transfer of the transmission line connected to each point, and a means for managing the number of free lines allocated for the data exchange among the communication channels, and a means for managing the number of free lines allocated for the data exchange among the communication channels. Checks whether there is an empty line allocated for the data exchange on the transmission line that connects to the specified delivery destination, and only when there is an empty line, calls are made to the specified destination to which the data has not been delivered, thereby sequentially receiving the specified delivery destination. This configuration has means for calling and distributing data. Communication between terminals between each point is performed by time division multiplex transmission using time slots assigned to each terminal type, and when sending and receiving data such as facsimile communication, it is first sent to the central storage and forwarding device. After accumulating this exchange data, the storage and forwarding device delivers it to the specified destination. When delivering to a terminal, a call is made to the other party's terminal, and if the line is blocked, a call is made again after a predetermined wait time to attempt delivery. However, this storage and forwarding device specifically manages the vacant time slots allocated for the data exchange, that is, the number of vacant lines, for transmission, and when there is a vacant channel among the communication channels, data is not delivered. The system checks whether there is a free line on the transmission line that connects to the designated delivery destination, and only when there is a free line, makes a call to the designated delivery destination to which the data has not yet been delivered. In this way, the designated distribution destinations are sequentially called and data is distributed only when there is an available line, so it is possible to suppress wasteful operations such as waiting for a predetermined period of time and re-calling due to no available line. Not only can distribution be performed efficiently in a short period of time, but by repeatedly re-calling waits due to no free lines, it is possible to prevent undelivered distribution due to exceeding the specified number of re-calls.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist thereof. However, it is also possible to use an end-to-end system that allows direct communication between terminals, and it can also be used for simultaneous broadcast distribution between personal computer terminals connected as terminal devices.

〔Effect of the invention〕

As described in detail above, according to the present invention, since available lines are grasped and calling operations are managed within this available line range, unnecessary calling operations, waits, re-calls, etc. can be suppressed. Digital communication has features such as not only being able to efficiently distribute image information in a short time by simultaneous broadcast transmission, but also eliminating the possibility of non-delivery termination caused by repeating waits and retries a specified number of times. Can provide web system.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an embodiment of the present invention;
FIG. 2 is a flowchart showing the operation of the present invention, FIG. 3 is a diagram showing a control table used in the device of the present invention, FIG. 4 is a diagram for explaining a conventional example, and FIG. 5 is a diagram for explaining the effects of the present invention. This is a diagram for 100...Storage and exchange device, 110...CPU section, 1
20... Communication control device, 121-123, 201~
203, 301-305... facsimile machine, 4
01-403...Private branch exchange, 501-503...
Multimedia multiplexing device, 601, 002... line.

Claims (1)

[Claims] The multiplexing devices to which the terminals are connected are connected by a transmission path, and communications between the terminals are time-division multiplexed using time slots assigned according to the type of terminal, and when transmitting and receiving data, Once this exchange data is stored in a central storage and forwarding device that has multiple communication channels and is capable of communicating with other party terminals for the number of communication channels, it is transmitted to the other party terminal on the called side when a call is made. If there is an empty time slot allocated for sending and receiving, the data is distributed via the multiplexing device through the line using the empty time slot, and if there is no empty time slot when the call is made, the data is re-called and distributed after a predetermined period of time has elapsed. In a high-speed digital communication network, the storage and forwarding device includes means for managing the number of free lines allocated for the data exchange on the transmission path between the multiplexing devices, and If there is a channel, check whether there is an empty line allocated for the data exchange on the transmission line corresponding to the specified destination for which data has not been delivered, and only when there is an empty line, make a call to the specified destination for which the data has not been delivered. A digital communication network system characterized by having means for sequentially calling designated distribution destinations and distributing data.