JP3451358B2 - Transmission control method for ISDN terminal device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an ISDN as a transmission line.
The present invention relates to a transmission control method for an ISDN terminal device to be used. 2. Description of the Related Art One of the service functions of ISDN is an incoming call.
There is a transfer function. This is triggered by a request from the receiving user.
Connected to the transfer destination specified by the called user,
Information can be transferred between the calling user and the transfer destination user
It is like that. [0003] Using this call forwarding function, for example,
If the user is moving to another location,
Accepts calls, improving ISDN usability
You. [0004] However, this is not the case.
The following inconveniences occur when the call forwarding function is used.
Is generated. For example, in a group 4 facsimile machine
Performs the image information transfer operation according to a predetermined transmission procedure.
ing. In this transmission procedure, the sending terminal and the receiving terminal
Various types of information are used to check functions and connectability.
I'm communicating. For example, in the session layer,
The terminal (sending terminal) is a connection in the session layer
Send a session start command CSS to set
Out, the receiving terminal (receiving terminal)
Confirm the mutual function by responding the RSS RSS
ing. At this time, for confirmation of the partner terminal, for example,
If the session start affirmative response RSSP
Contains the terminal identifier and the contents of this called terminal identifier
Is analyzed, and the calling terminal is the destination to which the destination terminal is specified.
Has been determined. By the way, as described above, the call transfer function
Allows the calling terminal to connect to the
If a call is established, the session start affirmative response
The value of the called terminal identifier included in the RSSP
The terminal identification information of the transfer destination terminal at the time of is set. On the other hand, the calling terminal starts the received session.
Called terminal identifier included in the positive response RSSP
Is compared with the terminal identification information of the first destination terminal. this
In that case, of course, they are in disagreement
Then, the calling terminal stops the information transfer operation at that time. Thus, the call transfer function is applied.
If this happens, the information transfer operation cannot be performed.
You. The present invention has been made in view of such circumstances.
The ISDN terminal that can properly utilize the call transfer function
It is an object of the present invention to provide a control method of a terminal device. SUMMARY OF THE INVENTION The present invention relates to the transmission of ISDN.
Transmission control method for ISDN terminal equipment used as transmission path
Storage means for storing the terminal identification information of the call transfer destination.
The called terminal sets the call transfer mode when an incoming call is detected.
The incoming call stored in the storage means
Release completion message with notification of the terminal identification information of the transfer destination
Message is rejected and the calling terminal is released when calling
A completion message is received and the release completion message is received.
If the message contains the caller's
Calls the notified call transfer destination and
An information channel has been established with the
The session user data of the procedure signal received from the
When the data contains the closed group number,
The preset closed group number and its communication
Compare known closed group numbers and find that they match
In that case, perform the subsequent information transfer operation and
While transferring information to the transfer destination, if there is no match,
The information transfer operation is terminated at
You. [0015] Therefore, not the ISDN function but the terminal
Since call forwarding is realized by its own function,
Inconsistency can be prevented and information is transferred from the calling terminal to the transfer destination terminal
The operation is performed properly. BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Examples will be described in detail. FIG. 1 shows a glue according to an embodiment of the present invention.
4 shows a F4 facsimile apparatus. This group 4
Facsimile machines use ISDN as a transmission path.
It is a terminal device. In FIG. 1, the control unit 1 mainly
Control processing of each part of Group 4 facsimile machine
Performs Group 4 facsimile transmission procedure processing of lower layer
The system memory 2 is executed by the control unit 1.
Execute the control processing program and the processing program
Data and other information necessary for
It constitutes the work area of the control unit 1 and has parameters
The data memory 3 includes, for example, terminal identification information of a call transfer destination,
Mode information for storing call transfer mode settings,
Or set to restrict the partner terminal to connect
This group 4 facsimile such as closed group ID
It is used to store various information unique to the
You. The scanner 4 scans a document image at a predetermined resolution.
For reading, the plotter 5 has a predetermined resolution.
It is for recording and outputting images in degrees.
6 is for operating the facsimile machine,
It consists of various operation keys and various indicators. The encoding / decoding section 7 encodes and compresses the image signal.
Image information that has been encoded and compressed
And the image storage device 8
It is also used to store a lot of image information in the state of encoding and compression.
It is. The ISDN interface circuit 9
Connecting a loop 4 facsimile machine to ISDN
The layer 1 signal processing function and D channel (signal channel)
Channel) and two B channels (information channels)
With signal integration / separation function, D channel
The transmission control unit 10 performs ISD such as call setup / call release procedure processing.
For performing signal processing on N D channels
And the B-channel transmission control units 11 and 12
Realizes the group 4 facsimile transmission procedure function performed by
It is for. The control unit 1, the system memory 2,
Parameter memory 3, scanner 4, plotter 5, operation table
Indicating unit 6, encoding / decoding unit 7, image storage device 8, D channel
Transmission control unit and B-channel transmission control units 11, 1
2 is connected to the system bus 13 and each of these
The exchange of data between elements is mainly based on this system.
This is performed via the bus 13. FIG. 2 shows the transmission of the group 4 facsimile apparatus.
4 shows an example of a transmission procedure. First, the originating terminal designates the intended destination terminal as the destination.
Sends the specified call setup message SETUP to ISDN
Requesting a call setup with the called terminal,
Is a call setup acceptance message to notify the call setup status
Send CALL_PROC to the calling terminal and specify
Sends a call setup message SETUP to the called terminal
Make a call. When the called terminal answers the incoming call, a response message
CONN to the ISDN, so that the ISDN
Sends a response confirmation message CONN_ACK to the called terminal
To check the response of the receiving terminal, and at that point,
Information channel for data transmission between terminals (B channel)
) Is established, so that the calling terminal and the called terminal
Initiate the transmission procedure on the channel. First, the calling terminal sends a command SABM
Request the link layer setting, and the called terminal responds
Responds UA. This sets the link layer
It is. Next, the calling terminal changes the network layer.
Send a signal SQ in order to extend end to end,
The called terminal sends out a signal SF to accept it,
Next, the calling terminal sends out a signal CR for a call request.
The called terminal responds to the signal CA and accepts the call.
Sets the network layer. Next, the calling terminal transmits a transport layer
Sends a signal TCR to set the
Sends a signal TCA to accept the
Then, a transport layer is set. [0030] Then, the calling terminal communicates with the session layer.
Start session command to set connection
The destination terminal sends a CSS and sends a session start affirmative response.
The response RSSP, and thereby the session
Ya is started. Next, the calling terminal negotiates the transmission function to be used.
Document function list command to associate
Send the CDCL, and the destination terminal
Sends a list of positive response RDCLP,
Thus, the reception capability is adjusted. In this way, the preparation for image information transmission is completed.
And the originating terminal sends a document to distinguish the document to be sent.
For managing document information to be sent, such as
Following the document start command CDS with various information
And a plurality of document user information commands CDUI
To send image information for one document, and terminate the transmission.
Sends a document end command CDE and sends 1
Notifies the end of document image information. The destination terminal receives a document end command CD.
When E is received, the reception of the document (image information) ends normally.
Document end positive response RDE
Send P. In this manner, image information transmission for one document is performed.
Upon termination, the calling terminal issues a session termination command CSE
And the destination terminal sends a session end positive response RS
Sends EP and releases session layer connection
Let go. Next, the originating terminal sends a message to the network layer.
Sends a signal CQ, to which the terminating terminal sends a signal CF.
Outgoing, thereby releasing the network layer.
Further, the calling terminal transmits a link layer command DIS.
C, the destination terminal sends a response UA,
With this, the link layer is released. Thus, the link on the B channel
When the (call) is released, the calling terminal releases the disconnect message DI
Send SC to ISDN to request release of information channel
ISDN sends a release message REL to the calling terminal
To notify the recovery of the information channel. On the other hand, ISDN
Sends a disconnect message DISC to the destination
Requesting the release of the channel, and the destination terminal issues a release message RE.
Sends L to ISDN to notify the recovery of the information channel
You. As a result, the calling terminal completes the channel disconnection.
Release complete message REL_COMP that notifies
Responds to the DN, thereby allowing a call between the calling terminal and the ISDN
The information channel is released. At the same time, ISDN
Sends a release completion message REL_COMP to the destination terminal.
Out of the information channel between the ISDN and the terminating terminal.
The channel is released. As a result, between the calling terminal and the receiving terminal
Is completely released. Thus, between the originating terminal and the destination terminal
An information channel is set up, data transmission takes place, and data
When the data transmission is completed, the information channel is released. Each of the ISDN call setup menus
The message is, as shown in FIG.
Protocol specifications (format,
Protocol identifier)
Identify which call the message is involved in
Call number to identify and the content of each message
Message types for each message
Required information elements that are always added, and
The message consists of additional information elements added to the message as needed.
You. The required information element depends on the message type.
0, 1 or more are set, and additional information elements
May have 0, 1 or more placed depending on the situation.
You. The call setup message SETUP is shown in FIG.
As shown in (b), “communication capability” is an essential information element.
The additional information elements include, for example, "calling number",
"Destination number", "Destination subaddress", "Lower layer matching"
, Higher layer consistency, and user
The information element such as "the". The release completion message REL_COM
P is, for example, “reason indication” as an essential information element.
The additional information elements include, for example, “display” and
And information elements such as "user / user". The outline of these information elements will be described.
You. The “transmission capability” information element is used to transmit information to be transmitted.
Content is audio, unrestricted digital information, restricted digital information
Report, 3.1KHz audio, 7KHz audio,
Or the ability to transfer information indicating whether it is video
Whether the switching function used is circuit-switched
The transfer mode and the speed of information transfer
Information transfer speed, information indicating the type of information transfer,
And information representing the protocol of user information
Become. The "calling number" information element is the ISDN of the calling terminal.
And the "destination number" information element is the IS of the destination terminal.
Represents the DN number. The “Destination subaddress” information element is
8 connected to the same house wiring (passive bus) on the receiving side
To identify the terminal of interest in
You. The "lower layer consistency" information element is
It is intended to be used for communication possibility check with the end,
The basic content is the same as the "communication capability" information element. Sa
In addition, this “low layer compatibility” information element
Includes padding content. The “higher layer consistency” information element is
It is intended to be used for consistency check with
For example, telephone, group 2 / group 3 facsimile, guru
Group 4 facsimile, mixed mode, teletex,
Videotex, Telex, Audio Visual
Or a message handling system
Which terminal functions have which terminal functions?
Or display. [0047] The "user / user" information element is between users.
It is intended to be used for transmitting
-The content of the "user" information element is interpreted by ISDN.
Without being transferred transparently.
Transmitted to the. The "reason display" information element is
Message (in this case, the release completion message REL_
COMP) was generated or occurred during the call setup procedure
Notify diagnostic information that indicates the reason for the error, etc.
It is for The "display" information element is transmitted from ISDN to the user.
This is for representing various display information with respect to. A session start affirmative response RS
The parameters included in the SP are, for example, as shown in FIG.
The terminal identifier (terminal identification information) of the destination terminal
Called terminal identifier, date / time information indicating date / time,
Service identification to identify the session service
Child and any user data, such as closed
Session user data that can place
You. The terminal identifier is as shown in FIG.
Up to 4 characters, country code, character
"-", Subscriber number up to 12 characters (ISDN number
No.) Additional information of up to 4 characters, characters
It consists of "=" and an abbreviation of three or more characters. Country
Up to 15 characters from code to subscriber number
The total length of the terminal identifier is 24 keys.
Fixed to the character. Therefore, this terminal identifier is notified.
Then, the terminal's ISDN number can be known. With the above configuration, the call transfer mode is set.
The operation when a called terminal is called will be described. The calling terminal sends a call setup message S to the ISDN.
ETUP is sent to call the terminating terminal, and ISDN
Then, a fixed message SETUP is sent to the destination terminal to make a call.
At this time, the destination terminal has the call forwarding mode set
Therefore, as shown in FIG. 5, the call transfer mode is indicated.
Display the call transfer mode information and the terminal identifier of the transfer destination terminal.
"User user" that sets the transfer destination terminal identification information
Release message REL_ to which the “user” information element is added.
Send COMP (UUI) to reject the incoming call. As a result, the ISDN is transmitted from the destination terminal.
Release complete message with "user / user" information element added
Page REL_COMP (UUI) to the calling terminal,
Notifies that the incoming call was rejected. Therefore, the calling terminal performs its call setting operation.
finish. Next, the transfer destination of the specified call transfer mode
ISDN for call setup message SETUP for calling terminal
To send to. If the transfer destination terminal can receive a call,
A call is established between the terminal and the transfer destination terminal, and an information channel
Enables the data transmission operation. Data transmission operation by information channel starts
Then, in the same manner as described above, the lower layer
Each layer is established in turn toward the
Upon receiving the fixed response RSSP, the calling terminal sets the
Session start acknowledgment RSSP called terminal identifier
Is displayed on the operation display unit 6 and, for example,
"Do you want to send image information to this transfer destination terminal?"
Guidance message to confirm the continuation of
Display to prompt the user for input to continue the transmission operation.
You. The user inputs an input for designating the continuation of the transmission operation.
Then, the calling terminal performs the subsequent processing in the same manner as described above.
Then, the document information is transmitted to the transfer destination terminal. documents
When the information transmission operation is completed, the call is disconnected and
Is terminated. At the same time
Is saved as a history. On the other hand, a gadget for confirming the continuation of the transmission operation
The user continues the transmission operation for the idance message
When an input for specifying not to be performed is made, as shown in FIG.
At that time, the calling terminal sends a session end command C
The SE is transmitted to terminate the image information transmission operation. Thereafter, the information channel is executed in the same manner as described above.
The call termination procedure and the call disconnection recovery procedure are executed.
Thus, a series of operations ends. At the same time,
The result of the image information transmission operation is stored as a history. In this way, the call transfer operation is performed.
You. In this case, for example, as shown in FIG.
Communication report is formed and recorded by plotter 5
Is output. In this communication result report, the communication date and time,
Destination information (eg, ISDN number), communication result, destination
A list of call forwarding information and information on the forwarding destination during call forwarding is displayed.
Have been. FIG. 8 shows a processing example at the time of calling. A call setup menu for calling a designated destination
When the message SETUP is transmitted (process 101), the message SETUP is released.
Completion message REL_COMP or response message
The message is received until the CONN is received (processing
102, NO loop of judgments 103 and 104). Answer message
Sage CONN is received, and the result of determination 104 is YES
, The process shifts to a normal calling process. When the release completion message REL_COMP is received
I believe that if the result of decision 103 is YES,
In the release completion message REL_COMP, "user
To see if the "user" information element has been added
(Decision 105). When the result of the judgment 105 is YES
Contains the contents of the "user / user" information element
It is checked whether the information is transfer mode information (decision 10
6). When the result of decision 106 is YES
Checks if the memory transmission mode is set
(Decision 107). When the result of the judgment 107 is NO
Then, the transfer process is started (process 108). When the result of the judgment 107 is YES,
Prompt, the user's confirmation operation cannot be performed.
-Save the content of the "user" information element (process 109),
The transmission operation ends in an error (process 110), and the fact is communicated.
Save as history. In addition, the result of judgment 106 is NO
If not, the process proceeds to step 109, where "user
Saves the contents of the "" information element and terminates the transmission operation with an error
Then, the fact is stored as a communication history. Also, judgment 10
When the result of Step 5 is NO, the process proceeds to Step 110.
The transmission operation with an error, and
save. FIGS. 9 and 10 show an example of the transfer process.
You. A call is made to the designated transfer destination (process 2).
01), execute a predetermined call setup procedure (process 202),
When an information channel is established (step 203), this information channel is established.
Started group 4 facsimile transmission procedure using channel
I do. The group 4 facsimile transmission procedure
Run and establish lower layers up to the network layer
(Process 204), the connection of the session layer is established.
Send session start command CSS to set
(Process 205), the session start affirmative
Receive the response RSSP (process 206). Here, this session start affirmative response
The contents of the RSSP are analyzed and the closed group ID is set.
Check whether it is included in the user data
(Decision 207). When the result of the judgment 207 is YES
Shows the contents of the closed group set in the terminal.
A check is made to see if they match the group ID (decision 208). When the result of decision 208 is YES
Executes the subsequent document transfer operation (process 2).
09) When the transfer operation is completed, the information channel
(Step 210) to disconnect and restore the call (Process 2).
11). At this time, since the communication operation has been completed normally,
Data indicating this is stored as a history (processing 2
12). The contents of the notified closed group ID
Matches the closed group ID set for the terminal.
If the result of the judgment 208 is NO,
At this point, the information channel end procedure is executed (process 21).
3) The call is disconnected and restored (process 214). At this time
Indicates that the communication operation has terminated with an error,
The data is stored as a history (process 215). Further, the closed group ID is not included.
When the result of the determination 207 is NO,
As mentioned above, the session start positive response RSSP
The content of the called terminal identifier is displayed on the operation display unit 6 and
For example, "Do you want to send image information to this
? For confirming the continuation of the transmission operation
A message is displayed (process 216). In that state,
Whether there is an input from the user before the fixed time elapses
Is monitored (NO loop of determinations 217 and 218). Until a predetermined time has elapsed, the user
Input, and if the result of decision 218 is YES,
It is checked whether the input is for continuation (decision 21)
9). If the result of decision 219 is YES,
The process proceeds to 209, where a document transfer operation is performed. When the result of determination 219 is NO
Then, the process proceeds to step 213 to terminate the transfer operation. Ma
For example, if the user is absent,
If the result of the determination 217 is YES, the processing 2
Then, the process goes to 13 to terminate the transfer operation. FIG. 11 shows a processing example at the time of receiving a call. When an incoming call is detected, the received call setting message
The SETUP is analyzed (process 301) to connect with the partner terminal.
It is checked whether or not it can be continued (decision 302).
If the result is NO, the incoming call is ignored (processing
303). When the result of decision 302 is YES
Checks if call forwarding mode is set
(Decision 304), and if the result of decision 304 is YES
Transfer mode information indicating the call transfer mode
And transfer destination terminal identification indicating the terminal identifier of the transfer destination terminal
Add a “user / user” information element that sets information
Release completion message REL_COMP (UUI) added
Is sent, and the incoming call is rejected (process 305). As described above, in this embodiment, when a call is made,
Release completion message that the called terminal notifies the call transfer mode
If REL_COMP (UUI) is returned,
The memory transmission mode is set
Error, the program terminates with an error and
Save known forwarding destination terminal information as communication history.
You. If the memory transmission mode is not set
Call the specified transfer destination,
Perform a transfer operation. At this time, the session
When the start positive response RSSP is received,
When it is determined that the loop IDs do not match
Does not transfer image information and keeps
-End. If the closed group IDs match,
In this case, the image information is transferred. If there is no closed group ID,
Whether to continue communication by presenting the called station identifier to the user
After confirming the will to continue,
Transferring information keeps communications secret
You. In the above-described embodiment, the terminal function
Realizes the call transfer function, but the ISDN call
You can also use the transfer function. One of the procedures in that case
An example is shown in FIG. The originating terminal sends a call setup message SETUP
Send to ISDN to call destination. ISDN calls
Sends a setup message SETUP to the specified destination terminal
Call the called terminal. ISDN also accepts call setup
Send the message CALL_PROC to the calling terminal. At this time, the call transfer mode is set to the destination terminal.
Is set, the called terminal
Announcement of receiving and notification of call forwarding destination
Send information message INFO (transfer) to ISDN
You. Thus, ISDN receives the designated incoming call.
Call setup that does not include the "Calling number" information element for the transfer destination
Message SETUP ". ISDN
Sends a disconnect message DISC to the destination terminal,
Disconnect and restore the last call. The transfer destination terminal includes the “calling number” information element.
No call setup message SETUP "
Recognizes that the incoming call is in call forwarding mode and redirects the call
Call transfer mode information indicating the mode and your own terminal
"User" including the transfer destination terminal identification information in which the identification information is set
Response message CON with the "user" information element added
N (UUI) to ISDN. ISDN forwarding
"User / User" with the same content as notified from the destination terminal
Response message CONN (UUI) with information element added
To the calling terminal. This allows the originating terminal and the destination terminal
And an information channel is established. Then, the calling terminal determines the transfer destination by the incoming call transfer.
It recognizes that it has been connected to the terminal and
・ The destination is the content of the destination terminal identification information of the `` user '' information element.
Replace the terminal identification information of the terminal, and in that state,
The image information transmission operation is performed on the file. End image information transmission operation
Upon completion, the call is disconnected and restored, and a series of operations ends. As described above, in the present embodiment, the transfer end
The end notifies the calling terminal of its own terminal identification information
Then, the calling terminal transmits the terminal identification information of the notified transfer destination terminal.
Group 4 facsimile transmission on the information channel using
For example, the session connection
When the called terminal identifiers do not match when
Can be avoided and appropriate image information transmission operation can be performed.
You. FIG. 13 shows a processing example at the time of calling according to the present embodiment.
And FIG. A call setup message for calling a designated destination
The SETUP is transmitted (processing 401), and a predetermined time has elapsed.
Before the response message CONN or release completion message
Monitors whether message REL_COMP is received
(Step 402, NO in determinations 403, 404, and 405)
Loop). When a response message CONN is received
If the result of decision 403 is YES,
Answer message CONN contains "user / user" information element
It is checked whether or not it is included (decision 406), and decision 4
If the result of step 06 is NO, the process proceeds to the normal calling process.
Run. When the result of decision 406 is YES
Checks if the call transfer mode has been notified
(Decision 407), when the result of the decision 407 is NO
Saves the "user / user" information element (processing
408), the process proceeds to a normal calling process. Judgment is made when the call transfer mode is notified.
If the result of step 407 is YES,
Check whether the re-transmission mode is set.
409). If the result of decision 409 is NO,
Information channel (step 410), and the established information
Data transfer in the above-mentioned call transfer mode is performed using a channel.
A sending operation is executed (process 411). When the data transfer is completed, the information channel is
The process ends (step 412), and the call is disconnected and restored (step 41).
3) Save the history data indicating the normal end (processing
414), a series of operations ends. When the result of decision 409 is YES
The call disconnect recovery action at that time.
(Process 415) In this case, it indicates an error end.
The history data is saved (process 416), and a series of operations is completed.
Complete. When the result of decision 404 is YES,
If the result of determination 405 is YES,
The process proceeds to the process 416, and ends with an error. FIG. 15 shows a processing example at the time of incoming call according to this embodiment.
Shown in When an incoming call is detected, the received call setting message
Analyze the SETUP (process 501) and connect with the partner terminal.
It is checked whether or not the connection can be continued (determination 502). Decision 502
If the result of the above is NO, the incoming call is ignored (processing
503). When the result of decision 502 is YES
Indicates "Calling number" in the received call setup message SETUP.
Check whether the information element is included (decision 50)
4). If the result of decision 504 is YES,
Check whether the transfer mode is set (decision 5
05). When the result of determination 505 is NO,
The processing shifts to the processing at the time of incoming call. When the result of decision 505 is YES
Indicates that the call transfer service will be received as described above.
Additional information message to notify
Sends INFO (transfer) (process 506) and disconnects the call
It recovers (process 507) and ends a series of operations. In the received call setup message SETUP
If the “calling number” information element is not included, the determination is 50
If the result of step 4 is NO, the call forwarding destination terminal
As described above, the call transfer mode is set to
Call transfer mode information and the terminal identification information of
“User user” including the set transfer destination terminal identification information
Response message CONN (UU
I) is sent to the ISDN (process 508). Next, a response confirmation message CONN_A
CK is received (step 509), and an information channel is established.
(Process 510) Group 4 file on the information channel
The information transfer is performed by executing the ximi transmission procedure (process 5).
11). When the information transfer ends, the information channel ends.
(Process 512), the call is disconnected and restored (Process 513),
End the repetition operation. In this embodiment, the call transfer mode
The user has not confirmed the information transfer,
Such an operation may be performed. Also, memory transmission
Occasionally, call forwarding mode is disabled
Call forwarding mode when sending to memory
You can also. In the above-described embodiment, the call transfer server
The procedure performed by ISDN when receiving a service request is
Of ISDN-specific procedures that do not conform to CCITT recommendations
However, when ISDN uses other procedures,
However, the present invention can be similarly applied. In the above-described embodiment, the present invention is a group.
Is applied to the Group 4 facsimile machine, but other
The present invention is similarly applied to an ISDN terminal device.
it can. As described above, according to the present invention,
Call forwarding with terminal-specific functions instead of ISDN functions
As a result, inconsistencies between terminals can be prevented,
The information transfer operation from the terminal to the transfer destination terminal is performed properly.
The effect is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a group 4 facsimile apparatus according to one embodiment of the present invention. FIG. 2 is a time chart showing an example of a transmission procedure of a group 4 facsimile apparatus. FIG. 3 is a schematic diagram showing formats of various signals. FIG. 4 is a time chart showing an operation in a call transfer mode according to one embodiment of the present invention. FIG. 5 is a schematic diagram showing an example of the content of a “user / user” information element. FIG. 6 is a time chart showing another case of the operation in the call transfer mode according to one embodiment of the present invention. FIG. 7 is a schematic diagram showing an example of a communication result report. FIG. 8 is a flowchart illustrating an example of processing at the time of calling. FIG. 9 is a flowchart illustrating a part of an example of a transfer process. FIG. 10 is a flowchart illustrating another part of the example of the transfer process; FIG. 11 is a flowchart illustrating an example of a process at the time of receiving a call; FIG. 12 is a time chart showing an operation example of a call transfer mode according to another embodiment of the present invention. FIG. 13 is a flowchart showing a part of another example of the processing at the time of calling. FIG. 14 is a flowchart showing another part of another example of the process at the time of calling. FIG. 15 is a flowchart showing another example of the process at the time of receiving a call;

Claims (1)

(57) [Claims 1] ISDN using ISDN as a transmission path
A transmission control method for a terminal device, comprising: storage means for storing terminal identification information of a call transfer destination, wherein a called terminal, when a call transfer mode is set at the time of detection of an incoming call, a call stored in the storage means. Sending a release completion message while notifying the transfer destination terminal identification information and rejecting the incoming call, the calling terminal receives the release completion message at the time of calling, and the call transfer destination terminal is included in the release completion message. If the identification information is included, a call is made to the notified call transfer destination, an information channel is established with the call transfer destination, and the session signal of the procedure signal received from the partner terminal in the session procedure. When the closed group number is included in the user data, the closed group number preset for the own terminal is compared with the notified closed group number, and the If they match, the subsequent information transfer operation is performed to transfer the information to the incoming call destination, while if they do not match, the information transfer operation is terminated at that time. Transmission control method.