JPH0352439A - Control method for data terminal equipment - Google Patents

Abstract

PURPOSE:To prevent a call issuing operation from being performed wastefully by judging the feasibility/infeasibility of re-call issuance and recall issuance interval time based on the content of a reason display information element included in a message for call disconnection or that of a call progress signal included in a packet for call disconnection. CONSTITUTION:When the message for call disconnection or the packet for call disconnection is received while performing a call setting procedure or data transmission by using a parameter memory 3 and a D channel (signal channel) transmission control part 11, the feasibility/infeasibility of the re-call issuance and the re-call issuance interval time are judged based on the content of the reason display information element included in the message for call disconnection or that of the call progress signal included in the packet for call disconnection. Therefore, the re call issuing operation corresponding to the status of a data communication network and that of an opposite terminal can be performed. Thereby, the call issuing operation can be prevented from being performed wastefully.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control method for a data terminal device that can determine whether or not re-calling is possible and the re-calling time.

[Prior Art] In a data terminal device that uses a data communication network such as ISDN (Integrated Digital Network) or PSPDN (Packet Switched Network) as a transmission path, there is a If some kind of failure occurs in the data communication network or the other party's terminal during data transmission after the connection is terminated, a predetermined procedure signal will be responded from the data communication network or the other party's terminal, and the requested call may not be established. An established call is disconnected.

In this way, when a call is not established or the call is disconnected, the data terminal device on the calling side calls the same terminal again and transmits the transmission information set in the data transmission operation.
Attempt to send to the other party's terminal. Furthermore, if all the transmission information cannot be transmitted in one re-call, the re-call is repeated up to a predetermined number of times in an attempt to transmit all the remaining transmission information to the other party's terminal.

[Problem to be solved by the invention] However, when the call is not established or the call is disconnected,
Depending on the status of the network or the other party's terminal, the call may not be established again or the call may be disconnected.

Conventionally, re-calling conditions were not specifically stipulated, so when a call was not established or the call was disconnected, a re-calling operation was always performed. Even when a failure occurs and there is no possibility that the call can be established, the call is repeatedly made to the other party's terminal, resulting in the inconvenience of wasted calling operations. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a data terminal device control method that can determine whether or not re-calling is possible and the re-calling time interval when re-calling.

[Means for Solving the Problems] The present invention provides that when a call disconnection message or a call disconnection packet is received during a call setup procedure or data transmission, a reason display information element or a call disconnection packet included in the call disconnection message is Based on the contents of the call progress multiple included in the call disconnection packet 11, whether or not re-calling is possible and the re-calling interval time are determined.

[Operation] Therefore, it is possible to perform a re-calling operation according to the situation of the data communication network and the other party's terminal, thereby preventing unnecessary calling operations.

[Example] Hereinafter, with reference to the attached drawings, lt. Examples of the present invention will be described in detail.

FIG. 1 shows a Group 4 facsimile machine according to one embodiment of the present invention.

The system control unit 1 performs processing for controlling the operation of each part of this group 4 facsimile machine, and the system memory 2 is used to execute a control processing program executed by the system control unit 1 and the control processing program. The parameter memory 3 stores various data specific to this group 4 facsimile machine, such as file management. It is used to store tables (described later) and the like.

Further, this parameter memory 3 is backed up by a battery.

The scanner 4 is for reading a document image at a predetermined resolution, and the plotter 5 is for recording and outputting an image at a predetermined resolution.

The operation display unit 6 is for operating this Group 4 facsimile machine, and consists of various operation keys such as a numeric keypad and one-touch dial keys, and various display devices such as a liquid crystal display. The encoding unit 7 is for decoding the encoded and compressed image information into the original rN signal whenever the image signal is encoded and compressed.

The image storage device 8 is for storing image signal files and image information files, and is composed of a large-capacity external storage device.

The ISDN interface circuit 19 is for connecting the ISDN and this facsimile machine, and the layer 1 signal control unit 10 is for connecting the ISDN! /D channel (signal channel) signal, which is used for layer 1 signal control and is mainly used for call control, and B channel (information channel) signal, which is used for data transmission. It also has the function of separating/integrating.

The D channel transmission control unit 11 is for performing ISDN call setup control using the D channel and transmission control processing for packet transmission, and the B channel transmission control unit 1243 is for performing ISDN call setup control using the D channel and transmission control processing for packet transmission. This is for performing transmission control processing for data transmission to be performed. The Bf-Yanel transmission control unit 12.13 also has a packet transmission function.

System control section 1, system memory 2, parameter memory 3, scanner 4, plotter 5, operation display section 6, encoding/decoding section 7, image storage device 8, D channel transmission control section 1
1. The B channel transmission control units 12 and 13 are each connected to a system bus 14, and various data such as control information and transmission data are exchanged between these elements via this system bus 14. .

Furthermore, the two B channel signals and the D channel signal on ISDN are handled by the layer 1 signal control section 10, the B channel transmission control sections 12 and 13, and the layer 1 signal control section 1.
The information is exchanged between the 0 and D channel transmission control sections 11.

FIG. 2 shows an example of the file management table FMT stored in the parameter memory 3. This file management table FMT is used to store various types of information necessary to perform set image information transmission, and one file management table is set for each image information transmission. In the figure, the file number FNO is for identifying each file management table FMT,
Call origination time information CT indicates the call origination time or re-call time specified by the operator. Destination number information CNO
represents the ISDN number of the destination, and the switching method information SM
D is for storing whether the switching method of L connected to the destination is circuit switching mode or packet switching mode.

The transmission mode information MDD is for storing the transmission function specified by the operator, and the transmission result information RE
"S" is for storing the result of image information transmission managed by this file management table FMT, and "calling in progress" indicates that a call is being made or a re-calling operation is in progress.
Either "Transmission OK" indicating that the destination has received all the image information normally, or "Transmission NGJ" indicating that the destination has not been able to receive the image information normally is set in the content.

The number of calls information CLT is for storing the number of calls made, and the transmission end page number information EPG is for storing the last page number among the pages successfully transmitted to the destination. Number information PGN is for storing the number of manuscripts to be transmitted, and page map information M
The PG is for storing the arrangement of storage areas occupied by image information in the image storage device 8 in units of pages.

This file management table FMT is created and stored in the parameter memory 3 at the time when the operator performs an operation to set both information transmission and the scanner 4 finishes reading the image copy of the transmission document. FIG. 3(a) shows an example of a call control procedure with ISDN in circuit switching mode.

That is, the originating terminal first sets the transfer mode L to the circuit switching mode, and also sends a call setup message SETUP specifying the destination terminal to the ISDN to request call setup with the destination terminal. The ISDN makes a call by sending a call setup message SETUP to the designated destination terminal. The ISDN also sends a call setup acceptance message CA port 7 PROC to the originating terminal to notify the call setup status. The destination terminal detects the incoming call, and when it is ready to receive the call, sends a paging message ALE to the ISDN.
RT is continuously sent at predetermined intervals, and the ISDN sends an alert message ALERT to the calling terminal to notify that it has started calling the called terminal.

The destination terminal responds to the incoming call by sending the response message CONN.
The ISDN sends a response message CONN to the calling terminal to notify that the called terminal has accepted the call.

In addition, ISDN sends a response confirmation message CON to the destination terminal.
N-ΔCK is sent and the response of the destination terminal is confirmed, at which point an information channel (B channel) for data transmission is established between the originating terminal and the destination terminal. Thereby, data transmission between the originating terminal and the destination terminal using the information channel is executed according to the transmission control procedure set in the transmission function of each terminal.

When the data transmission is finished, the originating terminal sends a disconnection message DISC to the ISDN to request release of the information channel, and the ISDN sends a disconnection message DISC to the destination terminal to notify the restoration of the information channel. .

As a result, when the destination terminal responds to the ISDN with a release message REL notifying completion of channel disconnection, the release message REL is sent from the ISDN to the originating terminal. When the channel release is completed, the originating terminal sends a release completion message RE.
I,COMP to notify the ISDN, which causes the ISDN to send a release complete message RHL-CO
By sending the MP to the destination terminal, the information channel is released, and the information channel set between the originating terminal and the destination terminal is completely released. In this way, an information channel is set up between the originating terminal L and the destination terminal H, data transmission is performed, and when the data transmission is completed, the information channel is released.

In addition, when the destination terminal does not respond with multiple calls, the same figure (b)
As shown in , when the terminating terminal receives the call setup message SETUP from the ISDN, it responds to the ISDN with a release completion message REL-COMP that includes the reason why it cannot respond to the incoming call.

As a result, the ISDN sends a release message RHL including the reason included in the release completion message REI, GOMP received from the destination terminal at that time to the originating terminal, and thereby the originating terminal transmits the release completion message REL COMP.
In addition, when the ISDN rejects the call from the calling terminal, it sends a release completion message RE1,C that includes the reason for the rejection, as shown in (C) of the same figure.
It responds with OMP to the originating terminal. This causes the originating terminal to release the call. Furthermore, during data transmission on the B channel, some failure may occur and the ISDN disconnects the call. In this case, the ISDN sends a disconnection message DISC containing the reason for the disconnection to each terminal. , recover the call.

In this way, when rejecting a call connection in circuit-switched mode and when disconnecting a communication bus once established,
Type of information element (reason display information element) that represents the reason included in the release completion message REL-COMP, release message REI, or disconnection message DISC
Table 1 below shows an example of the call control procedure with ISDN in packet switching mode. An example is shown. An example of this procedure is
A case where ISDN is equipped with a packet control function (packet handler) is shown.

First, the originating terminal sends a call setup message SETUP specifying packet mode as the transfer mode to the ISDN. As a result, the ISDN activates the packet control function, responds to the originating terminal with call setup acceptance messages CAL1 and PROC, and sends a response message CONN to the originating terminal.
Set up an information channel communication path with the originating terminal. In this way, upon receiving an information channel assignment,
The originating terminal sends a calling packet CR to the ISDN with the ISDN address of the terminating terminal set as the destination address. As a result, the ISDN recognizes the terminating terminal and sends the call setup message SETUP to the terminating terminal with the channel to be used set to channel B or D, and the communication mode set to packet mode. Send.

As a result, for example, when the destination terminal responds with a response message CONN in which the used channel is set to the D channel, the I
The SDN sets the D channel as a communication path and sends the incoming call packet CN to the destination terminal.

As a result, when the terminating terminal responds with the call acceptance packet CA, the ISDN sends a connection completion packet CC to the originating terminal, thereby establishing a packet communication bus between the originating terminal and the terminating terminal. ．． After this, a data transfer phase is executed between the originating terminal and the destination terminal according to the transmission procedure specified, and the sending file is transmitted from the originating terminal to the destination terminal. When the data transfer phase is completed, the originating terminal sends a recovery request packet CQ to the ISDN to request release of the communication bus with the destination terminal, and the SDN sends a disconnection instruction CI packet to the destination terminal. As a result, the destination terminal sends a disconnection confirmation packet CF to the access unit in order to release the communication bus, and the access unit sends a recovery confirmation packet CF to the origination terminal. In this way, when the packet communication path between the originating terminal and the destination terminal and the communication path between the originating terminal and the access unit are opened, the originating terminal sends the disconnection message DISC to the ISDN. to request release of the information channel, thereby causing the ISDN to send a disconnection message D
The ISC is sent to the destination terminal to notify that the information channel has been restored.

As a result, the destination terminal sends the release message REI to the ISD
In response to N, a release message REL is sent from the ISDN to the originating terminal. The originating terminal sends a release completion message R.
EI,COMP to ISDN, thereby
The DN sends a release completion message REL-COMP to the destination terminal, thereby completely releasing the information channel that was set up between the originating terminal and the destination terminal.

In this way, an information channel is established between the originating terminal and the destination terminal, a packet communication path is established on the information channel, and data transmission in packet mode is performed using the packet communication path. Then, when the data transmission is completed, the packet communication bus and the information channel are sequentially released.

In addition, if the destination terminal cannot respond to the incoming call,
As shown in , when the terminating terminal receives the call setup message SIETUP from ISDN, it sends a release completion message REL-COMP containing the reason why it cannot respond to the incoming call.
Respond to. As a result, the ISDN sends a disconnection packet CI including the reason included in the release completion message REI, COMP received from the destination terminal at that time to the originating terminal, and the originating terminal thereby releases the communication bus. A disconnection confirmation packet CF is sent to ISDN for this purpose, and from then on, the same figure (
In the same manner as in a), the information channel between the ISDN and the originating terminal is released and the call is restored.

In addition, when the ISDN rejects a call, as shown in FIG.
Sends. As a result, the originating terminal releases the communication bus, releases the information channel, and performs call recovery with the ISDN in the same manner as described above.

In addition, in packet switching mode, if the communication path cannot be maintained for some reason such as a failure during the data transfer phase, the ISDN sends a reset instruction packet to each terminal containing the reason for the disconnection. An RI or a restart instruction packet SI is sent. As a result, each terminal disconnects from the communication bus with the ISDN and restores the call.

In this way, in packet switching mode, a disconnection instruction packet CI and a reset instruction packet RI are used to disconnect a call.
．． Alternatively, Table 2 below shows an example of the relationship between the reason included in the restart instruction bag-RI (call request cancellation code) and the type of re-call.

Furthermore, the relationships in Tables 1 and 2 described above are stored in the parameter memory 3, respectively. With the above structure, the operator sets the original to be sent on the scanner 4, operates the operation display section 6, inputs the destination number, exchange method, and transmission function to be used at that time, and starts the sending operation. Then, the system control unit 1 operates the scanner 4 to read the transmission document set at that time, and
The image signal thus obtained is encoded and compressed by the encoding/decoding section 7, and the image information thus obtained is stored in the image storage device 8. When ε finishes storing both of these pieces of information, the system control unit 1
Regarding the transmission image file, the file management table FMT described above is used and stored in the parameter memory 3. At this time, when the call time is specified, the specified time is set as the call time information CTM, and if no time is specified, the call time information CTM is set.
Set the operation time at that time in TH. Further, "calling in progress" is set in the transmission result information RES, and "0" is set in the transmission end page number information EPG. On the other hand, when one or more B channel transmission control units 12.13 are in a usable state, the system control unit l
The transmission processing shown in FIGS. 5(a) to 5(d) is executed at appropriate timing.

That is, it is checked whether there is one or more file management tables FMT for which "calling" is set in the content of the transmission result information RES (determination l01), and if the result of determination lOl is YES, the corresponding Among the file management tables FMT, it is checked whether there is one or more file management tables FMT in which a time earlier than the current time is set in the contents of the call time information CTH (determination 1).
02), when the result of judgment 102 is YES, one of the corresponding file management tables FMT is selected (process 103). Then, the value of the number of calls information CLT of the selected file management table FMT is increased by one (process 104), and it is checked whether the value of the number of calls information CLT exceeds the limit value of the number of calls (judgment 105).

When the result of judgment 105 is YES, the number of re-calls exceeds the limit value, so the file management table FM
Set "Send NGJ" in T's transmission result information RES (
Process 106), the calling process ends.

Furthermore, when the result of judgment 105 is NO, the calling operation continues, so the file management table FMT
It is checked whether the packet switching mode is set in the switching method information SPID (decision 107). Judgment 10
When the result of step 7 is YES, the above-described packet mode call setup procedure is executed with ISDN (process 108).
．． A B channel is established (process 109), and a B channel layer 2 procedure is executed to establish B channel layer 2 (process 110). Then, it sends a call request packet CRttISDN set with the contents of the destination number information CNO in the file management table FMT as the destination, and calls the destination (processing 1l).
1) Receive a response from ISDN (process 11)
2). It is determined whether the received response is a connection completion packet CC or a disconnection instruction packet CI (determinations 1.13 and 11.4). The received response is a connection completion packet CC and a disconnection instruction packet CI.
If neither of the above is true, and the result of judgment 114 is No, the process ends with an error (process 1l5) and this transmission process ends. Here, upon receiving the disconnection instruction packet CI (result of judgment 114 is YES), the disconnection instruction packet C
The content of the call progress signal included in I is examined to identify the cause (processing 116), and the failure to transmit image information and the content of the problem are displayed and output from the operation display unit 6 (processing 1l7). With the re-call type content corresponding to the content of the call blog reply signal set as an argument,
Execute the call time resetting process (Processing) 18: Subroutine. In this call time resetting process, as shown in FIG. 6, the re-call type content given as an argument at that time is "possible", "rLONG allowed", "unknown", and "r not possible". (Judgment 201, 2)
02, 203), and if the re-call type content is "possible", judgment 201 is made.
If the result is YES, the content of the call time information CTM of the file management table FMT selected at that time is changed after 10 seconds (process 204), and the process returns to the original process.

If the re-call type content is “rLONG allowed”, judgment 202 is made.
When the result becomes YES, the content of the call origination time information CTM is changed after 60 seconds (process z05), and the process returns to the original process. When the re-calling type content is "unknown" and the result of the judgment 203 is YES, the content of the calling time information CTM is changed after 180 seconds (process 206), and the process returns to the original process. When the re-call type content is "not possible" and the result of judgment 203 is NO, "
Transmission NGJ is set (process 207) and the process returns to the original process.

In this way, when the call origination time is reset, the B channel release procedure is executed to release layers below layer 3 (processing 119).
), the call is restored (process 120), and this originating process is ended. Also, the packet received in process 112 is a connection completion packet CC, and the result of determination 113 is YE? When S is reached, the image information transmission pre-transmission procedure is executed, and if necessary, the transmission function is discussed with the other terminal (process 12l), and the transmission end page number information εPG of the file management table FMT selected at that time is Set the value plus 1 to the variable CPN for managing the page number to be sent (
Processing 122). Then, the file management table F selected at that time! Based on the contents corresponding to the (CPN) page of the 4T page map information MPG, the (C
PN) The image information of the page is read out from the image storage device 8 and sent to the destination (processing 123). At this time, each time one transmission unit is sent, the page ends or... A disconnection instruction packet CI, a restart instruction packet SI. and reset instruction packet RI
(Decision 124)
, 125 NO loops). When the transmission of image information for one page is completed and the result of judgment 124 becomes YES,
It is checked whether the value of the variable CPN at that time is greater than or equal to the value of page number information PGN of the file management table FMT selected at that time (determination 126).
When the result of judgment 126 is NO, there is a subsequent page, so a procedure signal is sent to the other party's terminal to notify the end of the page (process 127), and the signal returned from the other party's terminal causes the other party's terminal to It is checked whether the page was received normally (decision 128). When the other terminal receives normally and the result of judgment 128 is YES, the variable C
The value of PN and the value of the transmission end page number information EPG of the file management table FMT selected at that time are each increased by one (process 129), and the process returns to process 123 to transmit the image information of the next page. do. Also, if the other party's terminal cannot receive normally, judgment 128
When the result is No, the B channel is temporarily released to end the image information transmission (processing 130), the call is restored (processing 131), and it is confirmed that a transmission error has occurred and the page where the error occurred. The number is displayed on the operation display section 6 and the operator is notified of this (process 132), and the content of the call time information CTκ of the file management table FMT selected at that time is changed to 180 seconds ( Processing 1
33). This call processing ends. After sending all pages, the result of judgment 126 is YES.
When S is reached, the document has ended, so a procedure signal is sent to the other party's terminal to notify that the document has ended (process 134), and the signal received from the other party's terminal indicates whether the other party's terminal has successfully received the last page. (Judgment 135) When the destination terminal receives the data normally and the result of judgment 135 is YES, the transmission result information R of the file management table FMT selected at that time is
Set "transmission 0κ" to the contents of ES (process l36),
The B channel is released (process 137), the call is restored (process 138), and this communication process is ended. If the destination terminal cannot receive the data normally and the result of judgment 135 is NO, the process moves to process 130. Also, during image information transmission, a disconnection instruction packet CI, a restart instruction packet SI. Or, if one of the reset instruction packets RI is received, the result of judgment 125 is Y.
When it becomes ES, the received disconnection instruction packet C
I. Examine the contents of the call progress signal included in the restart instruction packet SI or the reset instruction packet RI to identify the cause (process 139). The fact that image information cannot be transmitted and the details of the cause thereof are displayed and output from the operation display section 6 (process 140), and with the re-call type content corresponding to the content of the call progress signal set as an argument, the process tig is Transition. On the other hand, if the switching mode is set to circuit switching mode and the result of judgment 107 is NO, a call setup message SETUP based on the contents of the file management table FMT selected at that time is sent to the ISDN. A call is made to the destination (process 141), and a response from the ISDN is received (process 142).

Then, it is determined whether the content of the response received at that time is a response message CONN, a release message REI, a release completion message RHL,..., COMP, or any other message (Judgment 14).
3, 144, 145). The received contents are a response message CONN, a release message REL, and a release completion message REL-CO.
If it is not any of the MPs (the result of judgment 145 is N
O), performs the process corresponding to the received message (process 146), returns to process 142, and receives the response message C.
ONN, a release message REL, and a release completion message REL-COMP are received.

When the release message REL is received and the result of judgment 144 is YES, the content of the reason display information element included in the release message REL is identified, the cause of the disconnection is identified (process 147), and the image information is The fact that the transmission cannot be made and the details of the cause thereof are displayed on the operation display unit 6 (process 148), and the call origination time is reset with the content of the recall type corresponding to the content of the reason display information element set as an argument. Setting processing (processing 149: subroutine) is executed.

Then, release completion messages REI, COMP are sent to the ISD.
N (process 150), and this transmission process ends.

Further, when the release completion message REI, COMP is received and the result of judgment 145 is YES, the cause of the disconnection is determined based on the content of the reason display information element included in the release completion message REI, COMP. Identification (processing 1
51) The fact that image information cannot be transmitted and the details of the cause thereof are displayed and output from the operation display section 6 (process 152). With the re-calling type content corresponding to the content of the reason display information element set as an argument, the calling time resetting process (process 153: subroutine) is executed, and this calling process is ended. Also, upon receiving the response message CONN, the judgment l43
When the result is YES, a B channel is established in circuit switching mode (processing 154), a pre-transmission procedure is performed to negotiate the transmission function with the other terminal (processing 156), and the selected terminal is selected at that time. A value obtained by adding 1 to the value of the transmission end page number information IEPG in the file management table FMT is set in a variable CPN for managing the page number to be transmitted (process 157).

Then, based on the content corresponding to the page map information MPG of the file management table FMT that is selected at that time, the image information of the page (CPN) is read out from the image storage device w8, and (Process 15g). Also, at this time, each time one transfer/borrow unit is sent, the page ends or the IS
It monitors the reception of a disconnection message DISC from the DN (No loop of decisions 159 and 160). When the transmission of image information for one page is completed and the result of judgment 159 becomes YES, the value of the variable CPN at that time is set to the file management table F selected at that time.
It is checked whether the page number information of the MT exceeds the value of PGN (determination 161).

When the result of judgment 161 is NO, it means that there is a subsequent page, so a procedure signal is sent to the other party's terminal to notify the end of the page (process 162), and the response signal from the other party's terminal causes the other party's terminal to It is checked whether the page was received normally (decision 163). When the other terminal receives normally and the result of judgment 163 is YES, the variable C
The value of PN and the value of the transmission end page number information EPG of the file management table FMT selected at that time are each increased by one (process 164), and the process returns to process 158 to transmit the image information of the next page. do.

Also, if the other party's terminal cannot receive normally, judgment 163
When the result is NO, the B channel is released in order to temporarily end image information transmission (process 165). The call is restored (processing 166), and the operator is notified that a transmission error has occurred and the page number that has occurred is displayed on the operation display section 6 (processing 167). Change the contents of the call time information CTM of the file management table FMT to 180 seconds (process 16
8) Finish this outgoing process. After sending all pages, the result of judgment 161 is YES.
When S is reached, the document has ended, so a procedure signal is sent to the other party's terminal to notify that the document has ended (process 169), and a signal is responded from the other party's terminal. Check whether the other party's terminal has successfully received the last page (decision 170). When the destination terminal receives the data normally and the result of judgment 170 is YES, the transmission result information R of the file management table FMT selected at that time is
Set "Send OKJ" in the ES content (process 171),
The B channel is released (process 172), the call is restored (process 173), and this communication process is ended.

If the other party terminal cannot receive normally and the result of judgment 170 is NO, the process moves to process 165.

In addition, when a disconnection message DISC is received during image information transmission and the result of judgment 160 becomes YES,
Releases the B channel (process 174), restores the call (process 175), examines the content of the cause information element included in the received disconnection message DISC to identify the cause (process 176), and restores the call (process 175). The same as above is performed, with the information that information cannot be transmitted and the cause thereof displayed and output from the operation display unit 6 (processing 177), and the recall type content corresponding to the content of the reason display information element set as an argument. The calling time resetting process (process 178: subroutine) is executed, and this calling process is ended. In this way, in this embodiment, when a call is not established during the call setup procedure or when the call is disconnected during data transmission, a call disconnection message is received from the ISDN to notify of these events. Based on the reason display information element included in the call disconnection packet or the content of the call progress signal included in the call disconnection packet, whether or not re-calling is possible and the re-calling time interval are identified. It is possible to perform a re-call operation according to the situation at the time of the call, and improve the efficiency of image information communication.

Furthermore, in this embodiment, image information is transmitted page by page, and pages for which transmission has not been completed are retransmitted at the time of re-calling.

Incidentally, in the above embodiment, the present invention is applied to a group 4 facsimile machine, but the present invention can also be applied to other data terminal equipment. In addition, in the embodiment described above, the re-call status is set to "possible", rL
It is classified into three types: ``ON OK'' and ``UNKNOWN'', and the re-call time interval for each is set to 10 seconds, 60 seconds, and 180 seconds. The setting value of the interval can be set appropriately according to the terminal characteristics and the like.

Furthermore, in the above-mentioned embodiments, the case where the ISDN is equipped with a packet control function has been explained, but the present invention can be applied in the same way even when the ISDN is not equipped with a packet control function and uses an access unit. can do. [Effects of the Invention] As explained above, according to the present invention, when a call disconnection message or a call disconnection packet is received during a call setup procedure or data transmission, the reason contained in the call disconnection message is Based on the display information elements or the contents of the call progress signal included in the call disconnection packet, it is determined whether re-calling is possible and the re-calling interval time. It is possible to perform a calling operation, thereby obtaining the effect that unnecessary calling operations are prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a Group 4 facsimile machine according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of a file management table, and FIG. 3(a) is a transmission procedure of ISDN in circuit switching mode. Figure 1 (b) is a time chart showing an example of the procedure when the called terminal rejects an incoming call in circuit switching mode. 4(c) is a time chart showing an example of the procedure when ISDN rejects a call in circuit switching mode, and FIG.
Time chart 1 showing an example of SDN transmission procedure, the same figure (b
) is a time chart showing an example of the procedure when the destination terminal rejects the call in packet switching mode, and (C) is a time chart showing an example of the procedure when the ISDN rejects the call in packet switching mode. (a) to (d) are flowcharts showing an example of a calling operation, and FIG. 6 is a flowchart showing an example of a calling time resetting process. 1... System control unit, 2... System memory, 3
...Parameter memory. Figure 3 (a) (b) (c) Figure 2 FMT

Claims (2)

[Claims] (1) In a control method for a data terminal device that uses ISDN as a transmission path, when a call disconnection message is received during a call setup procedure or data transmission, the content of the reason display information element included in the call disconnection message 1. A method for controlling a data terminal device, comprising determining whether or not re-calling is possible and a re-calling interval time based on the following. (2) In a control method for a data terminal device that transmits data in packet switching mode, when a call disconnection packet is received during a call setup procedure or during data transmission, the contents of the call progress signal included in the call disconnection packet are 1. A method for controlling a data terminal device, comprising determining whether or not re-calling is possible and a re-calling interval time based on the following.