JPH01195794A - Communication system - Google Patents

Abstract

PURPOSE:To surely attain an incoming call by controlling the transmission of a reply with respect to the incoming call at a terminal equipment based on the result of discrimination as to whether or not the incoming call informed from the network is to be accepted. CONSTITUTION:Plural terminal equipments 2-5 are connected as a bus formed on a transmission line connected to a prescribed network 1 and the notice of an incoming call from the network 1 to the terminal equipments 2-5 is applied simultaneously in a broadcast form. It is discriminated that the incoming call informed from the network 1 is received or not by the terminal equipments 2-5. The transmission is controlled so that an affirmative reply is sent with priority in the transmission of an affirmative reply or a negative reply with respect to the incoming call noticed from the network 1 based on the result of discrimination. Quick connection processing is realized by controlling the transmission of reply with respect to the incoming call and even when a terminal equipment able to accept the incoming call exists, the incoming call is processed surely.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a bus type communication system.

(Conventional technology) In recent years, communication networks including new media have developed significantly.
In order to realize more advanced and faster communication services,
Communication methods are transitioning from analog communication to digital communication.

The I5DN (Comprehensive Service Digital Ill4), which is currently being standardized internationally by the CCITT (International Telegraph and Telephone Consultative Committee), is a representative example of this, and is expected to become popular in various countries as a future communications network. .

The ISDN realizes a variety of services by integrating communication networks that were previously independent, such as telephone networks, data networks, facsimile networks, etc., into one.

For example, the basic interface specified in the CCITTI series recommendations has two information channels (
By multiplexing and transmitting signal channels (for transmitting information between terminals and exchanges) and signal channels (for transmitting information on quantity control between terminals and exchanges), up to 8 various communication terminals can be connected via bus on the same transmission path, and multiple It enables terminal communication.

Furthermore, with the basic interface in this ISDN, as shown in FIG. 3, a plurality of users A, B, .

By the way, in the case of a system as shown in FIG. 3, terminals with different attributes such as a telephone 2, a FAX 3, and a data terminal 4 may be connected, such as user B shown in the same figure.
Prior to communication, it is necessary to confirm consistency between the originating terminal and the receiving terminal. For this reason, CCITT Recommendation 1.451
(Layer 3) defines a procedure for checking consistency.

FIG. 4 shows a call/receive operation sequence based on the procedure specified by the CCITT recommendation for this consistency check. This example is when user A shown in FIG. 3 makes a call to user B using telephone 5. is assumed.

That is, as shown in FIG. 4, when user A makes a telephone call, an "r call setup" message in response to the call request is sent to the PBXI using a signaling channel. At this time, various call control messages are based on CCITT Recommendation 1.
441 (Layer 2) It is sent in an information (I) frame in the specified data link control procedure. That is, in this data link control procedure, first, user A
User A initializes layer 2 by sending SABME (Advanced Asynchronous Balanced Mode Command) to PBXI and receiving UA (Unnumbered Acknowledgment Response) from PBXI, and sends an I frame from User A to PBXI. This sends a "Call Setup" message. In addition,
This "call setup" message includes the other party's number and its own terminal attribute (telephone in this case). Furthermore, layer 2 has a unique address (W in this case) indicated by 0 in the figure, and is used in layer 2 frame transmission and reception.

When the PBXI receives this "Call Setup" message, it refers to the other party's number included in this "Call Setup" message and calls the specified party (in this case, user B).
) sends a "Call Setup" message to notify the incoming call. Here, in l5DN, in order to ensure the portability of user terminals, the PBXl side does not manage the connection status, attributes, etc. of user terminals, so the originating terminal (user A) and the receiving terminal (user B ), it is necessary to check the consistency between the Therefore, all terminals within User B, in this case telephone 2, FAX 3, and data terminal 4, must receive the "call setup" message that is normally sent to User B from the PBXI.

Here, since each terminal has a unique address (X), (Y), and (Z), the PBXI sends a "call setup" message to user B using a broadcast-type UI frame, and All terminals at B are notified of the incoming call.

Then, each terminal of this user B simultaneously uses this "
The terminal receives the "Call Setup" message, refers to the terminal attributes contained in this message, and performs a comparison check with the attributes of its own terminal. As a result, the terminals with matching attributes send a ``Call Setup J'' message to the PBXI, and the terminals with unmatched attributes send a ``Release Complete'' message including the reason for the attribute mismatch to the PBXI. The procedure for this is similar to the above-mentioned call from user A to the PBXI, in advance, from each terminal of user B to the PBXI
A data link setup procedure is executed in which a SABME including unique addresses (X), (Y), and (Z) is sent to each PBXI, and a UA is received from the PBXI.

On the other hand, after notifying the called side of the incoming call, that is, after sending a "call setup" message to user B, the PBXI waits for a response from the called side terminal for a predetermined period of time, for example, 1 second. data terminal (X) within the time
), a ``Release Complete'' message containing an attribute mismatch from the FAX (Y), and a ``Call'' message to accept an incoming call from the telephone (Z) are responded to. Then, the former performs a disconnection procedure, and the latter performs connection processing for the calling terminal, thereby realizing a call using the B channel.

As shown in Figure 5, the above procedure for making and receiving calls is performed by three layers: layer 1 (electrical physical layer), layer 2 (data link), and layer 3 (network) of the PBXI and the terminal. Realized.

In the example shown in FIG. 5, three types of terminals are connected to the signal channel from the PBXI: a data terminal, a FAX, and a telephone.
On the other hand, layer 2 provides unique data link parameters for each terminal, such as transmission state variable N(S), reception state variable N
(R) and other timers, etc., each terminal has an independent layer 2 for addresses (X), (Y), and (Z), and each layer 2 is multiplexed on the layer 1 signal channel. There is a need to. In this series of processing, the data links of layer 2 (X), (Y), and (Z) are sequentially processed by software of the same microprocessor in time-sharing processing.

By the way, in the example shown in FIG. 4, the terminal that cannot accept or accept incoming calls responds with the "release complete" message as described above, because there is only one terminal on the receiving side.
This is necessary to distinguish it from no response when no terminal is connected, but since the signal channel shown in Figure 5 is commonly used by all terminals, each terminal is It is necessary to monitor channel availability and send response information to the signal channel. However, the order in which this response is sent varies depending on the processing speed of the microprocessor inside each terminal, so in some cases, the "release complete" message, which is a negative response, is sent first, and the "call" message, which is an affirmative response, is sent later. This causes a problem in that the PBXI cannot proceed with connection processing until an acknowledgment is received, resulting in a delay in connection.

On the other hand, with ISDN, users can freely connect various terminals to the transmission path at any time, and the number of terminals is not particularly specified. However, on the network side such as PBXI, layer 2 (data link) control)
In order to realize miniaturization and cost reduction,
It is thought that the number of connected user terminals will be specified. In this case, assuming that the number of connected user terminals is n, the network only needs to realize n layer 2 and layer 3 that can control n terminals.

By the way, even though the number of Layer 2 devices that can be processed simultaneously on the PBXl side is set to n, if 0 or more terminals are connected to the transmission path, there is no terminal that can respond with an acknowledgment to an incoming call. Even if there is a response, if n terminals respond with a negative response and send a response first, the terminal that responds with an acknowledgement will not be able to set up a layer 2 data link, so for example, if the terminal that should respond with an acknowledgement sends a SABME to the PBXI. However, this terminal is PBXl
There is a problem in that the incoming call cannot be established because the tJA from the terminal cannot be received.

<Problems to be Solved by the Invention> In a communication system, such as the basic interface in ISDN described above, in which the network side notifies terminals connected to a bus on the same transmission path of incoming calls all at once in a broadcast format. In order to distinguish between cases where the terminal is not connected to the called side and cases where the attributes of the terminal do not match when a call is received, it is necessary for the called side to send a negative response to the network side indicating that the attributes do not match. be done.

For this reason, for example, depending on the processing speed of the microprocessor inside each terminal, there may be cases where a negative response is sent earlier than an acknowledgement, and in this case, the network side does not process the connection until the positive response is received. There is a problem that the connection cannot proceed and there is a delay in connection.

Additionally, if more terminals than the number that can be processed simultaneously on the network side are connected to the transmission path, and more than this number of terminals send negative responses first, no terminal can respond with an affirmative response to the incoming call. Even if there is, there is a problem that the call cannot be received.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a communication system that can not only realize quick connection processing but also can reliably receive a call if there is a terminal capable of receiving the call. It is an object.

[Structure of the Invention] (Means for Solving the Problems) The present invention connects a plurality of terminals in a bus-like manner on a transmission path connected to a predetermined network, and broadcasts notifications of incoming calls from this network to each terminal. Each terminal determines whether or not to accept an incoming call notified from the network, and controls the transmission of a response to the incoming call notified from the network based on the result of this determination.

(Function) In the present invention, each terminal controls the transmission of a response to an incoming call based on the determination result of whether or not to accept the incoming call notified all at once from the network in broadcast format, so that quick connection is possible. Not only can this process be realized, but if there is a terminal capable of receiving a call, the call can be received reliably.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 3 in the conventional example, the communication system according to an embodiment of the present invention is a system to which a basic interface in ISDN is applied, that is, a PBX.
A plurality of users A, B, etc. each have various communication terminals connected to the network by a bus. In particular, user A has only a telephone 5 as a terminal, and user B has only a telephone 5 as a terminal. 2, FAX 3 and data terminal 4.

Here, FIG. 1 shows a call originating/receiving operation sequence when the present invention is applied to the communication system having the configuration shown in FIG. 3, and the present embodiment will be described below based on this diagram. Note that the example in this figure assumes a case where user A makes a call to user B using telephone 5.

First, when user A makes a phone call to user B, user A sends SABME to the PBXI, and in response, user A receives UA from the PBXI, thereby initializing layer 2. , After that, user A sends a "call setup" message to the PBXI.

As a result, PBXI sends broadcast-type U
A "call setup" message in an I frame is sent.

Here, Figure 2 shows such "call setup" from PBXI.
It is a flowchart showing the operation of each terminal of user B that received the message.

That is, although the terminal is powered on, it remains in an idle state and waits until communication starts (step 201).

Then, as described above, upon receiving a "call setup" message from the PBXI notifying the incoming call (step 202)
The terminal attributes included in this message are compared with the own terminal attributes (step 203), and it is determined whether communication is possible (step 204).

Here, if the attributes match and communication is possible, the data link setting procedure by layer 2 is immediately executed. Note that in this case, the terminal of user B with matching attributes is telephone 2.

That is, user B's telephone 2 immediately sends SABME to the PBXI (step 205), and in response, user B's telephone 2 receives UA from the PBXI (step 20G), thereby initializing layer 2. After that, user B's telephone 2 sends a "ring" message to the PBXI (step 207), and the telephone 2 emits a ring tone. Then, a "call" message is sent to user A from the PBXI.

After this, when the receiver of user B's telephone 2 goes off-hook, this telephone 2 sends a "response" message to the PBXI, and the PBXI further sends a "response" message to user A. After that, the user A call between A's telephone 5 and user B's telephone 2 is made over the B channel (step 208).

On the other hand, if the attributes do not match and communication is not possible, a delay of, for example, about 250 to 500 nsec is applied (step 209), and then a data link setting procedure by layer 2 is executed. In this case, the terminals of user B whose attributes do not match are the data terminal and FAX3.

That is, after a "call" message is sent from user B's telephone 2 to user A's telephone 5 via the PBXI, that is, after an affirmative response is made at user B, user B's data terminal 4 and FAX
3 sends SABME to the PBXI (step 210), and in response, user B's data terminal 4 and FAX 3 receive the PBXI or AUA (step 211), initializing layer 2. From user B's data terminal 4 and FAX 3 to the PBXI,
"Release completed" message is sent (step 212)
.

Note that the user B's data terminal and FAX 3 then release the data link setting by transmitting the DISC to the PBXI (step 213) and receiving the UA in response (step 214), and return to the idle state.

In this way, in the communication system of this embodiment, if the receiving terminal cannot communicate because the attributes do not match, the data link setting procedure is executed after a predetermined time delay. A matching terminal can preferentially notify its response to the PBXI. For this reason, PBXI
After being notified of an incoming call, the user can immediately know that the incoming call has been accepted from the terminal, and can quickly proceed with the connection process.

Furthermore, even if more terminals are connected to the transmission path than can be processed simultaneously on the PBXI side, terminals with matching attributes will preferentially notify the PBXI of their responses. can reliably proceed with connection processing with a terminal that can communicate, and communication failures due to connection processing will not occur.

In the above-described embodiment, the terminal for communication was a telephone communication, but it may of course be a FAX 3, a data terminal 4, etc., and in the case of such a terminal that automatically receives a call when it arrives, It is also possible to immediately send a ``response'' message and enter into communication without sending a ``reply'' message.

Furthermore, in the above-described embodiment, the terminal attributes are compared and verified when a call arrives, and an affirmative response or a negative response is provided as a response. However, the present invention is not limited to this, and even if the attributes match, the If you cannot accept incoming calls,
For example, it can be implemented in the same way even when incoming calls are rejected, the terminal is in local mode, etc.

Furthermore, in the above-mentioned embodiment, a case was described in which both Layer 2 and Layer 3 operations on the terminal side are delayed at the time of a negative response, but the Layer 2 data link operation is performed in advance, and the Layer 3 message is delayed. Only the sending may be delayed.

By the way, in ISDN, since terminal portability is advocated, there may be cases where there is no response to an incoming call notification due to reasons such as the terminal not being connected to the transmission path. For this reason, the CCITT Recommendation stipulates that if there is no response within a certain period of time, for example about 4 seconds, the incoming notification should be retransmitted for confirmation.

The second embodiment shown below focuses on this point and applies the present invention.

Here, this second embodiment, like the embodiments described above, uses CCITT Recommendations 1.441 (layer 2), 1.45
1 (Layer 3), frames, messages, and procedures are used. 9. Layer 3 messages include call numbers to identify multiple calls,
In this second embodiment, this call number is stored to remember that there has been an incoming call, and is also used to distinguish between an incoming call waiting for retransmission and another incoming call.

Furthermore, as shown in FIG. 3 in the conventional example, the communication system according to the second embodiment also has multiple users A, B, and ...is configured with various communication terminals connected by bus,
In particular, user A has only telephone 5 as a terminal, and user B
has a telephone 2, a FAX 3, and a data terminal 4 as terminals. The call setup retransmission timer value when there is no response after call setup transmission is set to 4 seconds.

FIG. 6 is a flowchart showing the operation of each terminal when receiving a call in this second embodiment.

When the terminal is powered on, it enters an idle state and waits until communication starts (step 601).

Then, as described above, upon receiving a "call setup" message from the PBXI notifying the incoming call (step 602)
The terminal attributes included in this message are compared with the own terminal attributes (step 603), and it is determined whether communication is possible (step 60/I).

Here, if the attributes match and communication is possible, a data link setting procedure based on layer 2 is immediately executed (steps 605 to 608).

On the other hand, if the attributes do not match and communication is not possible, the data link setting procedure is not executed and the call number included in the "call setting" message is memorized (step 609).
) and start a 4 second timer (step 6
10).

When the "call setting" message is received again within this four seconds (step 602), the call number included in the "call setting" message is compared with the already stored call number (step 611).

Here, if these call numbers match, that is, if the "call setup" message is retransmitted, the timer is stopped (step 612), and the data link setup procedure by layer 2 is executed (steps 613 to 617). , clear the memorized call number (step 618)
.

Note that if the call number included in the "Call Setup" message received within 4 seconds does not match the already stored call number (step 611), this "Call Setup" message is not retransmitted. Since this is an initial message, it is treated as an initial "call setup" message.

Furthermore, if the "call setup" message is not received within 4 seconds (step 619), it is assumed that another terminal has responded to the initial "call setup" message, and the memorized call number is cleared (step 618). ) and becomes idle (step eoi).

Here, FIGS. 7 and 8 show a call origination/reception operation sequence when the terminal of this second embodiment is applied to the communication system having the configuration shown in FIG. 3. Note that the examples in these figures assume a case where user A makes a call to user B using telephone 5.

First, when user A makes a phone call to user B, user A sends SABME to the PBXI, and in response, user A receives UA from the PBXI, thereby initializing layer 2. , After that, user A sends a "call setup" message to the PBXI.

As a result, PBXI sends broadcast-type U
A "call setup" message is sent in l frames.

Then, as shown in Figure 7, if there is a terminal that has matching attributes and is capable of communication, this terminal immediately uses layer 2
The data link setting procedure is executed. Note that in this case, the terminal of user B with matching attributes is telephone 2.

That is, user B's telephone 2 immediately sends SABME to the PBXI, and in response, user B's telephone 2
By receiving UA from PBXI, layer 2 is initialized, and after that, user B's phone 2 sends a "call" message to PBXI, and this phone 2 makes a ring tone. . Then, the PBXI sends a "call" message to user A.

After this, when the receiver of user B's telephone 2 goes off-hook, this telephone 2 sends a "response" message to the PBXI, and the PBXI further sends a "response" message to user A. After that, the user A call between A's telephone 5 and user B's telephone 2 is conducted over the B channel.

On the other hand, data terminal 4 and FAX 3 whose attributes do not match
Terminal 2 does not perform such a data link setup procedure, but instead starts a 4-second timer and waits to resend the "Call Setup" message until the timeout. The "Call Setup" message will not be resent because you have already responded to
It remains in an idle state without executing the release completion procedure.

Furthermore, as shown in FIG. 8, for example, if telephone 2 is busy and there is no terminal with matching attributes, each terminal will not respond to the initial "call setup" message, so the "call setup" message will be retransmitted. will be done.

Then, each terminal executes the release completion procedure for the first time by receiving this retransmitted "call setup" message within the time set by its own timer.

In other words, each terminal of user B sends an SAB to the PBXI.
ME is sent, and in response, each terminal of user B sends PB
By receiving the UA from the XI, layer 2 is initialized, and then each terminal of user B sends a "release complete" message to the PBXI. And PBXI is
The reason for these “release complete” messages received by the CCI
The reason for the disconnection message is notified to user A's telephone 5 in accordance with the priority order specified in TT Recommendation 1.441, and the disconnection with user A's telephone 5 is restored and the link is released.

In this way, in the communication system of this embodiment, when there is a terminal with matching attributes, other terminals do not respond negatively, and only when there is no terminal with matching attributes, other terminals respond negatively. Therefore, after being notified of the incoming call, the PBXI can immediately know that the incoming call has been accepted from the terminal, and can quickly proceed with the connection process.

In addition, even if more terminals than the PBXl side can simultaneously process are connected to the transmission path, only the terminals with matching attributes will notify the PBXI of their responses, so the PBXl is reliable. It is possible to proceed with the connection process with a terminal that can communicate with each other, and failure of communication due to the connection process does not occur.

In the above-described embodiment, the terminal for communication was a telephone communication, but it may of course be a FAX 3, a data terminal 4, etc., and in the case of such a terminal that automatically receives a call when it arrives, It is also possible to immediately send a ``response'' message and start communication without sending a ``call'' message.

Further, in the above-described embodiment, the call number is used to identify whether or not the call has been retransmitted, but this may also be the calling number or the like.

Furthermore, although 4 seconds was set as the timer value for waiting for retransmission, considering the retransmission timer on the PBX side, there is a very low probability that the retransmission timer value on the PBX side or higher and the same calling number etc. will be used. It suffices if the distance is less than or equal to the interval.

Further, in this embodiment, consistency comparison is not performed at the time of call setup retransmission, but consistency comparison may be performed also at the time of retransmission.

In addition, in this embodiment, the case where release completion is sent only based on the consistency comparison result has been described, but if the local and
This can be implemented in the same way even when transmitting a release completion message when the terminal is busy during communication or the like.

Note that even when the present invention is applied to the ISDN basic interface, the present invention can be implemented within the scope of the procedures specified in the CCITT Recommendation, so the standard procedures will not be impaired.

[Effects of the Invention] As explained above, in the communication system of the present invention, the terminal controls the transmission of a response to an incoming call based on the determination result of whether or not to accept the incoming call notified from the network. Not only can a quick connection process be realized, but if there is a terminal capable of receiving a call, the call can be received reliably.

[Brief explanation of the drawing]

FIG. 1 is a call/receive operation sequence of a system according to an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the terminal according to FIG. 1, and FIG. 3 is a block diagram showing the configuration of a bus type communication system. FIG. 4 shows the call originating and receiving operation sequence of a conventional bus-type communication system, FIG. 5 shows the channel connection between the PBX and the terminal, and FIG. 6 shows the operation of the terminal according to the second embodiment of the present invention. The flowcharts in FIGS. 7 and 8 are call originating and receiving operation sequences of the system according to the second embodiment of the present invention. 1...PBX, 2.5...Telephone, 3...FAX,
4...Data terminal. Applicant: Toshiba Co., Ltd. Patent attorney Satoshi Suyama - Procedural Form 13 (spontaneous) ■ 1. 11 Indication Patent Application No. 1983-20629 2, Name of Invention Communication System 3, Person Making Amendment Relationship to the case / Patent applicant Toshiba Corporation 4, Agent 6, 2-1 Kanda Tamachi, Chiyoda-ku, Tokyo 101, Claims of the specification to be amended and details of the invention Explanation column 7, Contents of amendment (1) The claims of the specification are corrected as shown in the attached sheet. (2) Lines 1 to 7 of page 11 of the specification are corrected as follows. ``The present invention connects a plurality of terminals in a bus-like manner on a transmission path connected to a predetermined network, simultaneously broadcasts notifications of incoming calls to each terminal from this network, and allows each terminal to receive calls from the network. Determine whether or not to accept the notified incoming call, and control transmission based on the determination result so that the positive response is sent preferentially when sending an acknowledgment or negative response to the incoming call notified from the network. Attachment 2, Claims (1) A plurality of terminals are connected in a bus-like manner on a transmission path connected to a predetermined network, and the network notifies each terminal of incoming calls. In a communication system in which communication is carried out all at once in a broadcasting format, each of the terminals includes an incoming call determining means for determining whether or not to accept an incoming call notified from the network, and an incoming call determining means that determines whether or not to accept an incoming call notified from the network; A communication system comprising a means for receiving a call notified from.

Claims (1)

[Claims] (1) In a communication system in which a plurality of terminals are connected in a bus-like manner on a transmission path connected to a predetermined network, and the network notifies each of the terminals of incoming calls all at once in a broadcast format, An incoming call determining means for determining whether each terminal accepts an incoming call notified from the network; and a control means for controlling transmission of a response to the incoming call notified from the network based on the determination result by the incoming call determining means. A communication system comprising: