JPH04367143A - ISDN terminal equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ISDN terminal device.

0002

[Prior Art] Regarding ISDN call control, CCIT
T's recommendation Q. 931, and normal ISDN terminal devices comply with this recommendation.

[0003] When making a call, such a terminal device sends a call setup message "SETUP" to the ISDN network. Then, the ISDN network sends a call setup acceptance message “CA
LLPROC” is returned. A "channel identifier" indicating which of the two B channels is to be used is set in this message. When the terminal device receives the above message, it continues the predetermined call control procedure. Then, once a communication link is established with the other party,
Communicate using the B channel specified by the channel identifier.

By the way, in some countries, the above recommendation Q. 9
An ISDN network with some specifications different from that of 31 is also being constructed. In such a network, in response to sending a call setup message "SETUP", a call setup acceptance message "CALL P
A message different from "ROC" may be returned. For example, in the German ISDN network, a call setup confirmation message "SETUP_ACK" is sent back.

[0005] In such an ISDN network, the above-mentioned recommendation Q. 9
31-compliant terminal equipment is connected and a call is made, a call setup acceptance message “CALL PROC” is sent from the network.
' is not returned. Conventionally, in this case, the terminal device stopped the calling operation due to a communication error, so communication could not be performed.

[0006] By the way, various call control messages such as those mentioned above include "
protocol identifier.

[0007] The above-mentioned normal terminal device specifies "Recommendation Q.931" in its "protocol identifier."

[0008] On the other hand, some ISDN networks have their own standards set, and in that case, the ``protocol identifier'' specifies that the standard is ``domestic use''. A normal terminal device is connected to such an ISDN network, and the "SETUP" call setup message is
Assume that a call is made by specifying ``Recommendation Q.931'' in ``Protocol Identifier''.

[0009] Then, depending on the ISDN network, there are cases where the call setup message "SETUP" is not accepted and the call is disconnected by responding with the "release completion message "REL COMP". In this case, similarly to the above, communication could not be performed.

0010

SUMMARY OF THE INVENTION As described above, in the past, CCITT's Recommendation Q. There has been a problem in that normal terminal devices compliant with G.931 cannot be used in ISDN networks of various standards.

An object of the present invention is to solve the above problems and provide an ISDN terminal device that can be used in ISDN networks of various standards.

0012

[Means for solving the problem] For this purpose, the first part of the present application
In the invention, after transmitting a call setup message and making a call,
When a call control message other than call disconnection is received from the SDN network, the channel identifier information set in the call control message is read, and the predetermined call setup procedure is continued to establish a communication link with the other party. The information channel specified by the channel identifier information is used to communicate as usual.

[0013] Furthermore, the second invention is such that during a call setting procedure, protocol identifier information set in a received call control message is read, and the read protocol identifier information is a certain protocol identifier set by the device. If the information differs, the read protocol identifier information is set in various call control messages and the call setting procedure is re-executed.

[0014]

[Operation] According to the first invention, when a call control message other than call disconnection is received, the call setting procedure is continued. There will be no need to cancel. This allows the terminal device to be used in ISDN networks of various standards.

Further, according to the second invention, a situation where a call is disconnected by the ISDN network due to a difference in the protocol identifier information set in the call control message is avoided, so it is possible to execute the call setup procedure. can. This allows the terminal device to be used in ISDN networks of various standards, as described above.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a block diagram of a facsimile machine according to an embodiment of the present invention. In the figure, a scanner 1 is for reading original images, and a plotter 2 is for recording images on recording paper. The encoding/decoding unit 3 compresses the image information to be transmitted by a certain encoding, and restores the received image information to the original data.

[0018] The ISDN interface section 4 is an ISDN
It has a layer 1 function at the user/network interface of the network, and transmits and receives signals to and from the ISDN network via the network termination device NT. The D channel control unit 5 has layer 2 and layer 3 functions and executes call control procedures using the D channel. The B channel control unit 6
Image information is transmitted using a channel using a predetermined G4 facsimile transmission procedure.

The operation display section 7 is used to display the operating status of the device and to allow the operator to perform various operations on the device. The system control section 8 is a microcomputer that monitors and controls each of the above sections, and the system bus 9 is a signal line that exchanges various control information and data between the above sections.

With the above configuration, the transmission operation of the facsimile machine of this embodiment will now be explained.

[0021] When this facsimile machine makes a call,
As shown in FIG. 2, a predetermined call setup message “SETU
P'' (process 101) and monitors the response from the ISDN network (N loop of process 102).

[0022]Currently, ISDN networks and destination terminals are connected to CCITT.
Recommendation Q. 931 and is set to a general operating state. In this case, as shown in FIG. 3(a), the ISDN network sends the call setup message “SE
TUP" and sends it to the destination terminal. The destination terminal sends a call setup acceptance message "CALL PROC" and then sends a response message "CONN". IS
The DN network receives each of these messages and sends them to the originating terminal.

On the other hand, when the ISDN network or the destination terminal receives recommendation Q. 9
31, but is set to a different operating state. In this case, two cases are possible. First, as shown in FIG. 3(b), the ISDN network sends a call setup message "SETUP" to the destination terminal, and then responds to the originating terminal with a paging message "ALERT." Next, a response message "CONN" is sent from the destination terminal. The other is, as shown in Figure 3(c), I
The SDN network only transfers the call setup message "SETUP" and the response message "CONN".

Next, the ISDN network follows recommendation Q. If the call conforms to a standard different from G.931, another call control message is responded to the calling terminal. For example, the German IS
As shown in FIG. 3(d), the DN network sends a call setup confirmation message "SE" in response to the call setup message "SETUP".
"TUP_ACK" to the originating terminal. After this, the response message "CONN" is sent in the same manner as above.

In any of the above cases, when the ISDN network sends out the response message "CONN", a communication link is established between the originating terminal and the terminating terminal.

When the facsimile machine of this embodiment, which is a calling terminal, receives various call control messages from the ISDN network (Y in process 102 in FIG. 2), it determines whether or not it is a message indicating call disconnection (processing 103). Messages indicating call disconnection include, for example, the disconnection message "DISC" and the release completion message "REL C".
"OMP" etc.

Now, assuming that a call control message other than call disconnection is received as described above (N in process 103), the "channel identifier" of the received call control message is checked (process 104).

As shown in FIG. 4, each type of call control message has the following information set as essential information elements: ``protocol identifier,'' ``call number,'' and ``message type.'' In addition, the call setup message "SETUP"
After that, a "channel identifier" is further set as an additional information element in the above various call control messages responded from the ISDN network. The "channel identifier" is information that indicates which of the two information channels, the B1 channel and the B2 channel, is to be used.

If the "channel identifier" is set (Y in process 104), the facsimile machine reads the information (process 105). When the reception of the response message "CONN" is confirmed, predetermined communication is executed on the formed communication link using the information channel specified by the "channel identifier".

[0030] When the communication is completed, the process shown in Fig. 3(a)
), the facsimile machine sends a disconnection message "DISC". The ISDN network sends the disconnection message "DISC" to the terminating terminal, and sends it to the originating terminal which has received the release message "REL" sent from the terminating terminal. Then, the originating terminal sends the release completion message “RE
The ISDN network sends this message to the destination terminal and disconnects the call (process 10 above).
6).

By the way, channel identifier information may not be set in the received call control message, for example, when there is a failure in the ISDN network. In this case, (N of 104
), performs predetermined error processing such as error display (process 107), and then cancels the calling operation. Also, from the ISDN network, a disconnection message "DISC" and a release completion message "
If a message indicating call disconnection such as "REL COMP" is received (Y in process 103), the calling operation is also stopped.

[0032] As described above, in this embodiment, after the call setup message "SETUP" is sent and a call is made, not only the call setup acceptance message "CALL PROC" but also the call control messages responded in various ISDN networks are sent. , read the "channel identifier" at that time,
Call setup procedures and data communications are carried out as usual. This allows facsimile machines to be used in ISDN networks of various standards.

By the way, in the above embodiment, when the facsimile machine sends out the call setup message "SETUP" to make a call, depending on the protocol identifier to be set, the ISDN network may send out the call setup message "SETUP".
There may be cases where the call is disconnected without being accepted.

Next, another embodiment of the present invention corresponding to such a case will be explained.

The "protocol identifier" is information that is always set in various call control messages, as explained with reference to FIG. This information is 8-bit data, and as shown in FIG. 5, CCITT Recommendation Q. If it is a call control message compliant with G.931, it will be expressed as “08H” in hexadecimal notation.
” is set. On the other hand, when operating under a standard different from that recommendation, "40H" in hexadecimal notation is used.
It is now possible to set one of the codes ``4FH'' to define it as ``domestic use.''

In this embodiment, when making a call, the "protocol identifier" is first set according to the recommendation Q. 931
"08H" indicating the call setup message "SET
UP” (process 201). Then, the response from the ISDN network is monitored (N loop of process 202).

When a call control message of some kind is received, the "protocol identifier" set in the message is read (process 203), and its code is determined (process 204).

[0038] By the way, the ISDN network is
If the ISDN network only supports the standard, as shown in Figure 7, the ISDN network will not accept the call setup message "SETUP" and will immediately respond with a release completion message "REL COMP" which means call disconnection. . In this case, the "protocol identifier" of the call control message is "4
One code from "0H" to "4FH" is set.

[0039] If the code of the received "protocol identifier" is not "08H", the facsimile machine
Step 204 (N), change the "protocol identifier" to the code just received (step 205).

Thereafter, the changed "protocol identifier" is set in the call setup message "SETUP" and a call is made again (process 206). As a result, the ISDN network
Accepts the sent call setup message "SETUP". The facsimile machine then executes a predetermined call setup procedure. This allows predetermined communication to be performed.

As described above, in this embodiment, the received "
If the code of the "protocol identifier" is different from the code set by the device, the "protocol identifier" is changed to the received code and the call setup procedure is repeated.

[0042] Therefore, the situation where the ISDN network disconnects due to the difference in protocol identifiers is avoided.
Call setup procedures can be performed. This allows the terminal device to be used in ISDN networks of various standards.

[0043] In each of the above-mentioned embodiments, explanations have been given taking the case of a facsimile machine as an example, but the present invention
It goes without saying that the present invention can be applied in exactly the same way to various terminal devices used in the N network.

[0044]

As described above, according to the first invention, when a call control message other than call disconnection is received from the ISDN network after sending a call setup message and making a call, the call control The channel identifier information of the message is read to continue the given call setup procedure and communicate using the designated information channel as usual, so that the Since communication is no longer interrupted, the terminal device can be used in ISDN networks of various standards.

Further, according to the second invention, if the protocol identifier information of the received call control message is different from the protocol identifier information set by the device, the read protocol identifier information is used in various call control messages. , and re-executes the call setup procedure, thereby avoiding the situation where the call is disconnected by the ISDN network due to a difference in protocol identifiers, and allowing the predetermined call setup procedure to be executed. Similarly, the terminal device can be used in ISDN networks of various standards.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart of the calling operation of the facsimile machine.

FIG. 3 is an explanatory diagram of call setup procedures in each case.

FIG. 4 is an information configuration diagram of various call control messages.

FIG. 5 is an explanatory diagram of a code definition of a protocol identifier.

FIG. 6 is a flowchart of a calling operation in another embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an example of a call setting procedure in the embodiment.

[Explanation of symbols]

1 Scanner 2 Plotter 3 Encoding/decoding section 4 ISDN interface section 5 D channel control section 6 B channel control section 7 Operation display section 8 System control section

Claims (2)

[Claims] [Claim 1] In an ISDN terminal device that transmits a call setup message and makes a call, and then continues a certain call setup procedure and communicates when a specific call control message is responded from the ISDN network, a response receiving means for receiving various call control messages responded from the ISDN network; a call canceling means for canceling the call when the received call control message indicates call disconnection; channel information reading means for reading the channel identifier information set in the call control message if the call control message does not indicate the meaning; and communication link forming means for continuing the call setting procedure to form a communication link with the other party. An ISDN terminal device comprising: communication execution means for communicating using an information channel specified by the channel identifier information of a communication link. [Claim 2] In an ISDN terminal device that executes a call setup procedure by sending various call control messages in which certain protocol identifier information is set,
response receiving means for receiving various call control messages responded from the N network; protocol information reading means for reading protocol identifier information set in the received call control message; ISDN characterized in that it is equipped with a call setting re-execution means for setting the read protocol identifier information in various call control messages and re-executing the call setting procedure when the read protocol identifier information is different from the protocol identifier information.
terminal device.