JPH03106158A - Communication system - Google Patents

Abstract

PURPOSE:To prevent repetition of redialing by referencing an information channel number included in control information received from a network, monitoring the operating state of an information channel and restricting the dialing depending on the operating state of the information channel. CONSTITUTION:Control information representing the operating state of an information channel is sent to a network by using a terminal line number as an incoming number, and the network utilizes the service of notice in broadcast form to lines and the operating state is informed to other terminal equipments on a bus of the line. Thus, it is possible to identify the operating state of the information channel by other terminal equipments on the bus and the state of dialing restriction is informed prior to hook-off or dialing of opposite party. Thus, useless operation by the user is prevented.

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to a communication terminal that is applied to a communication system in which a plurality of communication terminals can be connected via a bus on a line that multiplexes and transmits a plurality of information channels. (Conventional technology) In recent years, communication networks including new media have developed significantly.
In order to provide advanced and more diverse communication services, efforts are being made to transition from analog communication to digital communication. The ISDN (Integrated Services Digital Network), 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 spread to ordinary households in the future as a future communication network. It is expected that In this ISDN, communication networks that were previously independent for each terminal, such as telephone networks, data networks, and facsimile networks, are integrated into one network, and multiple communication channels are provided through one subscriber line. The development of a variety of services will be realized. For example, in the ISDN basic interface specified in the CCITT I series recommendations, communication information is digitally multiplexed in a specified format, so that normal g! A major feature is that three channels can be used simultaneously: two information channels (for terminal-to-terminal information communication; 64 Kbps) and one signal channel (terminal-to-network control information; 16 Kbps) by using the telephone line as is. It is. Furthermore, the in-home system (CC) of this basic interface
The ITT series recommended interface reference point (S/T point) allows up to eight different types of communication terminals to be connected to the bus on the same 4a type line. Therefore, in a general household, it is easy to install a telephone or the like in each room by wiring a bus-type transmission line in each room. By the way, as mentioned above, when multiple terminals are wired in a bus type on the same subscriber line, multiple terminals are apparently connected to one subscriber number, so the above-mentioned ISDN basic interface does not handle incoming calls. A simultaneous call reception method is adopted. Using Figure 4, make and receive calls using this simultaneous call receiving system.
The operation sequence for incoming calls will be explained. First, when the caller picks up the telephone handset (off-hook) and enters the number of the other party, a signal called a "call setup" message is generated and sent to the network (exchange) via the signaling channel described above. Ru. this"
The "Call Setup" message includes a carrying function that specifies the telephone;
A channel identifier that specifies the channel B1/B2 to be used and a called party number that specifies the destination number are encoded in a prescribed format. When the network receives this "call setup" message, it refers to the called party number, selects the line of the called party, and sends a "call setup" message to notify the called party of the incoming call using a broadcast format signal. Furthermore, addresses indicating the destination and source of various signal messages in addition to the "call setup" message are assigned in advance to each of the terminals on the calling side and the receiving side. For this address, an address (X) for a broadcast format that does not specify the destination is defined. By the way, the signal channel is commonly used by all terminals connected to the bus for sending and filling the signal channel, so when a signal message is received from the network, it is necessary to input the address of the own terminal and the signal message. The attached addresses are compared, and if they do not match, the signal message is discarded. In addition, if the addresses match or if the broadcast format is used, the terminal performs an operation corresponding to the content as a signal message to its own terminal. In Figure 4, a "call setup" message that notifies the called party of the incoming call is sent from the network using a broadcast format address (X), and is sent to three telephones (
1, 2, and 3) simultaneously receive the "call setup" message and begin incoming calls all at once. In this case, a ring tone sounds from each telephone at the same time to notify the user of the incoming call, and each terminal sends a "ring" message to the network indicating that the called party is calling. At this time, the address 1.2.3 unique to each terminal is added to each "call" message, so that the network temporarily stores the address of the terminal being called. When the user picks up the handset from one of the three phones that is ringing (in this case, the phone with address 3), a "response" message is sent to the network informing the user that the phone will accept the call from that device. Sent. When the network receives this "response" message, it sends a "response confirmation" message, and by exchanging the above-mentioned information channel between the calling and called parties, the telephones 3 on the calling and called parties enter a conversation state. enter. On the other hand, for telephones 1 and 2 that are ringing,
A "release" message to which each address is added is transmitted from the network side, and after receiving this message, telephones 1 and 2 stop ringing, transmit a "release complete" message, and return to the ready state. In this way, with the simultaneous call reception method, any terminal on the bus can accept calls, so in a typical home, users can pick up the phone no matter where they are in the room.
When used in an office, anyone can pick up any phone on the same bus, which is very convenient. By the way, the calling procedure in the ISDN basic interface described above has the following disadvantages. That is, whether or not other communication terminals connected to the bus on the same transmission path are communicating is determined according to CCITT Recommendation Q. 931 and cannot be identified from the prescribed procedure. Therefore, even if all information channels (two information channels in the basic interface) are in use by other communication terminals on the same bus before a call setup is sent from a certain communication terminal,
As shown in Figure 5, once a request is made to the network to set up a call, the network that manages the allocation of information channels determines that there is no information channel available on the same line, and the terminal that sent the call request is The request is rejected by sending a release completion message. (Problem to be Solved by the Invention) In a bus-type communication system such as the ISDN 21 interface, it has been impossible to determine the usage status of information channels at other communication terminals on the same transmission path. There is a problem in that even if a call request is sent to the network while all channels are in use, the request is rejected by the network and the user's off-book and dialing operations are wasted. [Structure of the Invention] (Means for Solving the Problems) The present invention, which solves the above-mentioned conventional problems, is directed to a communication system in which a plurality of communication terminals can be connected via a bus on a line that multiplexes and transmits a plurality of information channels. When the terminal is assigned an information channel to be used for communication by the network in the outgoing/incoming call setup procedure, the terminal has means for transmitting control information in a predetermined format including the channel number to the network using the line as the destination. , comprising a monitoring means for monitoring the usage status of the information channel by referring to the information channel number included in the control information received from the network, and a means for restricting transmission based on the usage status of the information channel by the monitoring means. Features. (Function) In the present invention, control information indicating the usage status of an information channel is transmitted to the network using the line number of the terminal as the called party number, and the network uses a service to notify the line in broadcast format. Notify other terminals on the bus. Therefore, it is possible to identify the usage status of the information channel at other terminals on the bus, and it is possible to notify the user of the call restriction state before the user goes off-hook or dials the other party when making a call. Therefore, it is possible to prevent the user from performing unnecessary operations. (Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sequence showing a calling/terminating operation in a communication system in which telephones to which the present invention is applied are connected via a bus. In Figure 1, there is one telephone on the calling line and one telephone on the receiving line. After the three telephones 2 and 3 are connected to the bus, and an information channel is assigned by the network in the sequence on the calling side and the sequence on the called side, the information channel number is sent to the user. This shows the operation of including it in the summary and notifying the user's own number. The control information in the user-to-user information included in the call setup message addressed to the own number is looped back over the network and is notified in broadcast format to each terminal connected to the bus. Figure 2 (a) shows the format of a call setup message used for making and receiving calls, including the transmission function of the own terminal, a channel identifier that specifies the information channel to be used, and a called number that indicates the number of the other party. Contains information elements. On the other hand, FIG. 2(b) shows the format of a control information call setup message for notifying the information channel number after the information channel is assigned by the network on the calling and receiving sides. In this control information call setup message, the channel identifier specifies no information channel, and a channel that is used after the called party number or is no longer in use (Bl or B
Contains a user/user information element indicating the specification of 2) and information indicating whether to start or end use. Next, FIG. 3 shows an outline flowchart of the operation of this telephone. When this telephone receives the control information in the format shown in FIG. (referred to as "table")
(step 82). When making a call from this telephone, when the user goes off-hook (step S3), the "information channel table" is referred to (step 84). If there is no free channel (step S5), a busy tone is sounded to restrict outgoing calls (step S6). If there is an empty channel (step S5), the user is prompted to input the dial number of the other party, and after completing the input, a call setup message is sent and the calling procedure is started (step S5).
7). When the other party's terminal responds, it transmits control information that includes the channel used in the communication and user information about the users in use, and sets its own number as the called party number (step S8);
Notify bus-connected terminals of channel usage status. On the other hand, if the call is received (step S9), a calling message is sent and the call reception procedure is started (step S10).
). When the user goes off-hook, a response message is transmitted, and control information containing a user-to-user information element indicating the channel to be used and whether it is in use, and in which the called number is set as the own number is transmitted (step S12). This control information is looped back through the network and terminals connected to the bus are notified of the usage status of the channel. Furthermore, at the end of communication, control information is sent that includes the channel that was being used when the channel was released and the user information that indicates the end of use, and sets the called number to the own number (
Steps 813 and 14) notify the bus-connected terminals that the channel has become vacant. As described above, it becomes possible to identify the usage status of the information channel at other terminals on the bus, and it is possible to notify the user that the user is in a call-restricted state before going off-hook or dialing the other party when making a call. Therefore, it is possible to prevent the user from performing unnecessary operations. Note that in this example, the present invention was applied to a telephone, but
The present invention may be applied to a FAX, a data terminal, a key telephone device, or the like, or may be a dedicated terminal for monitoring channel usage status. Furthermore, the communication system is not limited to ISOH, but can be applied to a bus-type communication system that multiplexes and transmits a plurality of information channels. Furthermore, call setup messages and user-to-user information are used as control information to notify the channel usage status, but these are ignored. Further, the operation is not limited to that shown in FIG. 3. Further, in this embodiment, the user is notified of the availability of a channel by a busy tone when off-hook, but the availability of a channel may be displayed in advance using an LED or the like on the terminal.

【Effect of the invention】

As explained above, according to the present invention, it is possible to identify the usage status of other terminals on the same bus, and it is possible to identify the usage status of other terminals on the same bus. can be informed. Therefore, it is possible to prevent the user from performing unnecessary operations such as inputting a dial and repeatedly making a re-dialing, making the system more convenient and easier to use.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a sequence when a terminal to which an embodiment of the present invention is applied is connected to a bus and calls are made and received, and FIG.・Format of incoming call setup message, Figure 2 (b)
) is the format of the control information call setup message used in the embodiment to which the present invention is applied, Figure 3 is a flowchart showing the operation of the terminal to which the present invention is applied, and Figure 4 is the format of the call originating using the conventional simultaneous termination method. Operation Sequence: FIG. 5 is a conventional operation sequence when there are no vacant channels. 1, 2.3...Telephone, Bl, B2...Channel. (0-) dde≧4*4i wealth ￥I Tomihei 13k. Emmett-5゜゜(
4) *req information m'ttLU-yq->”Figure 2 Figure 3 @ Figure 4 Figure 5

Claims (1)

[Scope of Claims] In a communication terminal of a communication system in which a plurality of communication terminals can be bus-connected on a line that multiplexes and transmits a plurality of information channels, an information channel used for communication from a network in an outgoing/incoming call setting procedure. has means for transmitting control information in a predetermined format including the channel number to the network using the channel as a destination, and referring to the information channel number included in the control information received from the network. A communication terminal comprising a monitoring means for monitoring the usage status of an information channel, and a means for restricting transmission based on the usage status of the information channel by the monitoring means.