JP2000261570A - Isdn communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To property execute the fallback of a communication operation by selecting a 2nd terminal function in the case that first dialing is made to a designated destination in a state that a 1st terminal function is selected and designated and a dialed call is failed, and dialing the same destination in a state that the selected 2nd terminal function is designated. SOLUTION: A terminal function is set to a group 4 facsimile equipment function. A setup message is generated and sent to an ISDN to monitor and acknowledgement of the message from the ISDN. The terminal equipment receives the message from the ISDN and checks whether it is a disconnection message (DISC) or a release completion (REL-COMP). In the that the message is not added with a 'reason indication' information element due to the cause of the singularity of the ISDN or the like, the terminal equipment checks presence of setting of a forced fallback mode, checks its contents when a fallback condition indicates a reason display value, and the terminal equipment conducts prescribed procedure processing and executes proper redialing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ISDN communication terminal device having a plurality of terminal functions or a plurality of calling parameters.

[0002]

2. Description of the Related Art Conventionally, ISDN using ISDN as a transmission path
The SDN facsimile apparatus has a group 4 facsimile terminal function and a group 3 facsimile terminal function. For example, at the time of calling, one of the terminal functions according to the terminal function of the partner terminal is selectively used.

Also, in such an ISDN facsimile apparatus, when a call is made while a group 4 facsimile terminal function is first selected and a connection fails due to a reason that a partner terminal does not respond, a notification from the network is made. The group 3 facsimile terminal function is switched to the selected state based on the value of the reason display information element in the disconnection message to be performed, and a recall operation is performed.

[0004] Such a switching operation of the terminal function is called a fallback function, which enables a communication operation to be performed properly even if, for example, the user who made the call makes a mistake in the device function of the partner terminal. Becomes

[0005]

However, such a conventional apparatus has the following disadvantages.

That is, when the fallback is performed according to the value of the cause information element responded from the network, the value of the cause information element that can be fallbacked differs depending on the country.
In addition, it may be necessary to change the value of the reason display information element to fall back due to a change in the standard or the use status (frequency) of the reason display information element. There was a problem that it had to be changed and it was troublesome.

The present invention has been made in view of the above circumstances, and has as its object to provide an ISDN communication terminal device capable of appropriately performing fallback of a communication operation.

[0008]

According to the present invention, in an ISDN communication terminal device having a plurality of terminal functions, a first terminal function is selected, and the selected first terminal function is specified in a specified state. The first call operation to the destination is performed, and if the call connection related to the call fails, the second terminal function is selected, and the same second terminal function is designated and the same It is provided with call control means for making a call to a destination.

Further, in an ISDN communication terminal device having a plurality of terminal functions, a first terminal function is selected, and an initial call operation is performed to a specified destination in a state where the selected first terminal function is specified. And if the call connection for the call fails, the second terminal function is selected and the selected second terminal function is specified, regardless of the content of the reason for the failure of the call connection. And call control means for making a call to the same destination.

Further, in an ISDN communication terminal device having a plurality of terminal functions, a first terminal function is selected, and an initial call operation is performed to a specified destination in a state where the selected first terminal function is specified. And the call connection for the outgoing call is I
In the case of disconnection from the SDN, even if the content of the disconnection reason is “absent”, the second terminal function is selected, and the selected second terminal function is specified, and the same destination is specified. It is provided with call control means for performing a calling operation.

Further, in an ISDN communication terminal device having a plurality of terminal functions, a first terminal function is selected, and an initial call operation to a specified destination is performed in a state where the selected first terminal function is specified. And the call connection for the outgoing call is I
When the connection is disconnected from the SDN, the state of the own terminal user side of the D channel layer 3 that receives the disconnection message received from the ISDN is checked, and when the state is a predetermined content, the second terminal function is selected. And call control means for making a call operation to the same destination in a state where the selected second terminal function is designated.

Further, in an ISDN communication terminal device having a plurality of terminal functions, a first terminal function is selected, and an initial call operation is performed to a specified destination in a state where the selected first terminal function is specified. And the call connection for the outgoing call is
A call control unit for selecting a second terminal function when a failure has occurred due to a timeout on the own terminal side, and making a call operation to the same destination while specifying the selected second terminal function; Things.

Further, in an ISDN communication terminal device having a plurality of terminal functions, a first terminal function is selected, and an initial call operation to a specified destination is performed in a state where the selected first terminal function is specified. If the call connection for the outgoing call fails, if the content of the reason for the failure of the call connection is a predetermined one, the re-call operation is performed with the first terminal function selected. If the content of the reason for the failure of the call connection is other than the predetermined reason, the second terminal function is selected, and a call is made to the same destination in a state where the selected second terminal function is designated. It is provided with call control means. Further, the second terminal function has a fallback relationship with the first terminal function.

An IS having a plurality of calling parameters is provided.
In the DN communication terminal device, a first calling parameter is selected, a first calling operation is performed to a specified destination in a state where the selected first calling parameter is specified, and a call connection for the calling is performed. If the call fails, a call control means for selecting a second call parameter and performing a call operation to the same destination with the selected second call parameter specified is provided.

An IS having a plurality of calling parameters is provided.
In the DN communication terminal device, a first calling parameter is selected, a first calling operation is performed to a specified destination in a state where the selected first calling parameter is specified, and a call connection for the calling is performed. Has failed, the second call parameter is selected regardless of the content of the reason for the failure of the call connection, and the call is sent to the same destination with the selected second call parameter specified. It is provided with call control means for performing operations.

Further, an IS having a plurality of calling parameters is provided.
In the DN communication terminal device, a first calling parameter is selected, a first calling operation is performed to a specified destination in a state where the selected first calling parameter is specified, and a call connection for the calling is performed. Is disconnected from the ISDN, the second call parameter is selected, and the same is specified in the state where the selected second call parameter is specified, even if the content of the disconnect reason is “absent”. And a call control means for making a call operation to the destination.

Further, an IS having a plurality of calling parameters is provided.
In the DN communication terminal device, a first calling parameter is selected, a first calling operation is performed to a specified destination in a state where the selected first calling parameter is specified, and a call connection for the calling is performed. Is disconnected from ISDN, I
A state of the user of the own terminal of the D channel layer 3 which has received the disconnection message received from the SDN is checked, and when the state has a predetermined content, a second calling parameter is selected, and the selected second calling parameter is selected. A call control means for making a call operation to the same destination with a designated call parameter.

An IS having a plurality of call parameters is provided.
In the DN communication terminal device, a first calling parameter is selected, a first calling operation is performed to a specified destination in a state where the selected first calling parameter is specified, and a call connection for the calling is performed. However, in the case of failure due to a timeout on its own terminal side, call control for selecting a second calling parameter and performing a calling operation to the same destination with the selected second calling parameter specified Means.

An IS having a plurality of calling parameters is provided.
In the DN communication terminal device, a first calling parameter is selected, a first calling operation is performed to a specified destination in a state where the selected first calling parameter is specified, and a call connection for the calling is performed. Fails, if the content of the reason for the failure of the call connection is a predetermined one, the re-call operation is performed while the first calling parameter is selected,
If the contents of the reason for the failure of the call connection are other than the predetermined reason, the second call parameter is selected, and the call operation to the same destination is performed with the selected second call parameter specified. It is provided with call control means for performing. Also,
The second calling parameter has a fallback relationship with the first calling parameter.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described in detail.

FIG. 1 shows an ISD according to an embodiment of the present invention.
1 shows an N facsimile machine. The ISDN facsimile apparatus uses ISDN as a transmission path and has a group 3 facsimile apparatus function, a group 4 facsimile apparatus function, and a call function.

In FIG. 1, the control unit 1 controls the ISDN
The system memory 2 executes operation control processing of the facsimile apparatus, group 3 facsimile transmission procedure processing, group 4 facsimile transmission procedure processing of the upper layer, and call procedure processing. It stores various data necessary for executing the processing program and constitutes a work area of the control unit 1.

The parameter memory 3 is for storing various information unique to the ISDN facsimile apparatus, and is a nonvolatile (rewritable) data such as a battery-backed SRAM (static random access memory). It comprises a semiconductor storage device.

The character generator 4 is for generating various font data, and includes a clock circuit 5.
Is for obtaining current time information.
Is for reading a document image at the resolution set for the group 4 facsimile function, and the plotter 7 is for recording and outputting the image at the resolution set for the group 4 facsimile function.

The operation display section 8 is for operating the ISDN facsimile apparatus, and includes various operation keys,
And various display devices such as a liquid crystal display for displaying guidance information and the like to an operator.

The encoding / decoding section 9 encodes and compresses the image signal by a predetermined encoding method (MH, MR, MMR, etc.) and decodes the image information in the encoded and compressed state into the original image signal. The pixel density conversion unit 10
When the pixel density of the image of the scanner 6 and the plotter 7 is different from the pixel density of the image that can be transmitted by the terminal device of the other party, the pixel density is mutually converted.

The image storage device 11 stores various information such as a transmission image signal, transmission image information, reception image information and a reception image signal.

The ISDN interface circuit 12
The layer 1 signal control unit 13 is used to physically connect to a DN and a signal processing function of the ISDN layer 1 and a D channel (signal channel) signal and two B channel (information channel) signals. It has an integration / separation function.

The D channel transmission control section 14 is for performing transmission control processing such as call control processing performed with ISDN using the D channel.
This is for performing an analog signal / digital data signal conversion process for transmitting an analog signal using the DN B channel.

The B channel transmission control section 16 is for performing layer 2, 3, 4, and 5 transmission control processing in group 4 facsimile transmission control processing using the ISDN B channel (information channel).

The group 3 facsimile modem 17 is for realizing a modem function of group 3 facsimile, and a low-speed modem function (V.21 modem) for exchanging transmission procedure signals and mainly for transmitting image information. High-speed modem function for communication (V.17 modem, V.17 modem)
34 modem, V.34. 29 modem, V.29. 27ter modem etc.).

The switch 18 is for switching and connecting the CODEC 15 to one of a group 3 facsimile modem 17, a handset 19 for talking, and a speaker 20 for outputting a ringing tone or the like.

Control unit 1, system memory 2, parameter memory 3, character generator 4, clock circuit 5, scanner 6, plotter 7, operation display unit 8, encoding / decoding unit 9, pixel density conversion unit 10, image storage device 11, Layer 1
Signal control unit 13, D channel transmission control unit 14, CODE
C15, B channel transmission control unit 16, group 3 facsimile modem 17, and switch 18 are connected to the internal bus 2
1, and various kinds of information are exchanged between these elements mainly through the internal bus 21. A hook signal FS indicating a hook state of the handset 19 is transmitted to the control unit 1 via the internal bus 21.
Has been added to

FIG. 2A shows an example of a call control procedure performed by a telephone terminal connected to ISDN with ISDN. The ISDN facsimile apparatus executes the same procedure as the present procedure for the call control procedure.

That is, the originating terminal first sets the circuit switching mode as the transfer mode, sends a call setup message SETUP designating the destination terminal as the destination to ISDN, and requests the ISDN to set up a call with the destination terminal. Sends a call setup message SETUP to the designated destination terminal to make a call. Further, the ISDN sends a call setting acceptance message CALL_PROC for notifying the call setting status to the calling terminal.

Upon detecting the incoming call, the called terminal sends a call message ALERT to the ISDN when the own terminal is ready to receive a call, and the ISDN sends a call message ALERT to the calling terminal to call the called terminal. Notify that it has started.

When the user picks up the handset and answers the incoming call, the called terminal sends a response message CONN to the ISDN.
And the ISDN sends a response message CONN to the calling terminal to notify that the called terminal has accepted the call.

The ISDN sends a response confirmation message CONN_ACK to the destination terminal to confirm the response of the destination terminal. At that time, the B channel for data transmission (call) between the calling terminal and the destination terminal is established. Once established, a call operation using the B channel is appropriately performed between the user of the calling terminal and the user of the called terminal.

When the call ends and the user of the calling terminal returns the handset first and goes on-hook, the calling terminal sends a disconnection message DISC to ISDN to request release of the B channel, and ISDN sends a release message REL.
Is sent to the calling terminal to notify that the B channel has been restored. On the other hand, the ISDN sends a disconnect message DISC to request the release of the B channel to the called terminal, and the called terminal sends a release message REL to the ISDN to notify that the B channel has been restored.

As a result, the originating terminal sends a release completion message REL_COMP for notifying the completion of channel disconnection to IS
In response to the DN, the B channel between the calling terminal and the ISDN is released. At the same time, the ISDN sends a release completion message REL_COMP to the destination terminal,
The B channel between the terminal and the destination terminal is released. Thereby, the B channel set between the calling terminal and the called terminal is completely released.

In this way, the B channel is set between the calling terminal and the called terminal, data transmission is performed, and when the data transmission ends, the B channel is released.

When the called terminal cannot answer the incoming call, as shown in FIG. 2B, when the called terminal receives the call setup message SETUP from the ISDN, the called terminal completes the release completion message REL_COMP including the reason why the incoming call cannot be answered.
To the ISDN.

Thus, the ISDN sends a release message REL including the reason included in the release completion message REL_COMP received from the destination terminal at that time to the calling terminal, whereby the calling terminal transmits the release completion message RE
In response to L_COMP, release the call.

When the ISDN rejects the call from the calling terminal, the ISDN responds to the calling terminal with a release completion message REL_COMP including the reason for the rejection, as shown in FIG. As a result, the calling terminal releases the call.

When the call connection initiated by the calling terminal is disconnected, a disconnection message DISC is responded to the calling terminal,
A disconnect / release procedure may be initiated.

As shown in FIG. 3 (a), each message for ISDN call setting is a protocol specification (format, format,
Protocol identifier)
A call number to identify which call the message is involved in, a message type to identify the content of each message, mandatory information elements that are always added to each message, and each message And additional information elements that are added as needed. Note that 0, 1, or a plurality of essential information elements are set according to the message type, and 0, 1, or a plurality of additional information elements are arranged according to the situation.

The call setup message SETUP has "communication capability" as an essential information element, as shown in FIG.
The additional information elements include, for example, "calling number",
"Originating subaddress", "Destination number", "Destination subaddress", "Lower layer compatibility", "Higher layer compatibility",
And it has information elements such as "user".

The disconnection message DISC and the release completion message REL_COMP have, for example, "reason display" as an essential information element and "display" as an additional information element, as shown in FIG. "And" user ".

The outline of these information elements will be described.

The “transmission capability” information element indicates whether the content of the information to be transmitted is voice, unrestricted digital information, restricted digital information, 3.1 KHz audio, 7 KHz audio, or video. Capability, transfer mode indicating whether the switching function used is circuit switching or packet switching, information transfer speed indicating information transfer speed, information indicating information transfer mode, information indicating user information protocol, etc. Consists of

The “calling number” information element is the ISDN of the calling terminal.
The "calling subaddress" information element represents a number and is used for purposes such as terminal identification on the calling terminal side.
The “destination number” information element indicates the ISDN number of the destination terminal. The “destination subaddress” information element is used for purposes such as terminal identification on the destination terminal side.

[0052] The "lower layer consistency" information element is to be used for a communication possibility check with the partner terminal.
The basic content is the same as the "communication capability" information element. Further, the "lower layer consistency" information element includes more detailed contents.

The "higher layer compatibility" information element is used for checking the compatibility with the partner terminal, and includes, for example, telephone, group 2 / group 3 facsimile, group 4 facsimile, mixed mode, teletex,
Displays which terminal function is provided among terminal functions such as Videotex, Telex, Audio-Visual, and Message Handling System.

The “user / user” information element is used for transmitting information between users, and the content of the “user / user” information element is transmitted transparently without being interpreted by ISDN. It is transmitted to the other user.

The "reason indication" information element is a diagnosis indicating the reason why the message (in this case, the disconnect message DISC or the release completion message REL_COMP) containing the information element was generated, the reason for the error that occurred during the call setup procedure, and the like. It is for notifying information and the like.

The "display" information element is for displaying various display information from the ISDN to the user.

FIG. 4 shows an example of a process executed by the ISDN facsimile apparatus regarding a call connection.

First, with the terminal function set to the group 4 facsimile apparatus function, the above-mentioned call setup message SETUP is created, sent to ISDN, and called to the destination (process 101).

Then, it is monitored whether a message is received from ISDN (decision 102). If no message can be received from ISDN, the result of decision 102 is N
When it becomes O, it becomes a predetermined timer T303 (T
It is checked whether or not it is the first time-out according to TC Recommendation Q.931 (decision 103).

Here, when a message is received from the ISDN and the result of the judgment 102 is YES,
It is checked whether the received message is a disconnect message DISC or a release completion message REL_COMP (decision 104).

If an appropriate call connection is possible, the decision 104
If the result is NO, then the predetermined call processing is continuously executed, and the image information communication operation using the group 4 facsimile apparatus function is executed using the information channel set at that time. (Not shown).

On the other hand, when the disconnection message DISC or the release completion message REL_COMP is received and the result of the decision 104 is YES, it is checked whether or not the received message contains a "reason display" information element (decision). 105).

For example, if the "reason display" information element is not added due to the specificity of ISDN or the like and the result of determination 105 is YES, this I
It is checked whether or not the forced fallback mode is set in the SDN facsimile machine (decision 106). Here, the forced fallback mode means that if a call connection operation fails when a call is made using the group 4 facsimile apparatus function, regardless of the value of the "reason display" information element at that time, the (forced fallback mode) This is a mode in which the function is switched to the group 3 facsimile apparatus function and a recall operation is performed.

When the result of determination 106 is NO,
The fallback condition set in the ISDN facsimile apparatus is a reason indication value or TT
D channel layer 3 specified in C / Q.931
It is determined whether the value is a state value representing the state of the call setup procedure in (Step 107).

When the fallback condition is a state value of a state, the state value at that time is a value representing a state before the completion of the call connection, that is, a state number “0” representing an empty state, and a call state representing a call state. State number "1" representing a divided call state, state number "2" representing a call acceptance state, state number "3" representing a call acceptance state, or state number "4" representing a call notification state,
It is checked whether the state value is set to the fallback state (decision 108).

If the result of decision 108 is NO,
With no fallback, the terminal function is reset to the group 4 facsimile apparatus function, and the apparatus shifts to the recall standby state (step 109), and executes a predetermined recall procedure.

If the fallback condition is a reason display value in the judgment 107, it is checked whether or not the content is a content showing a specific reason (decision 110). Here, the specific reason includes "# 16: normal end".

When the result of the judgment 110 is YES, the process shifts to a process 109 in order to shift to a re-call operation with the same terminal function, and the result of the judgment 110 is N
When it becomes O, in order to perform fallback operation,
In a state where the terminal function is set to the group 3 facsimile apparatus function, a predetermined fallback procedure process is executed (process 111), and the process proceeds to the next calling procedure process.

When the fallback condition is a state, the state value at that time is a value representing the state before the completion of the call connection, and when the result of the judgment 108 becomes YES, the processing shifts to the judgment 110. , Inspects the contents, and executes a process according to the inspection result. That is, in this case, even in the fallback state, either the fallback procedure to the G3 FAX or the recall procedure in the G4 FAX is activated depending on the contents of the reason display value.

If the forced fallback mode is set at that time, the result of decision 106 is YES
When it becomes, the process proceeds to the process 111 to execute the process of the predetermined fallback procedure.

In addition, the message "Reason display"
When the information element is not included and the result of the determination 105 is NO, the process shifts to a process 111 to execute a process of a predetermined fallback procedure.

On the other hand, as described above, when the message cannot be received from the ISDN,
Is reached, a predetermined timer T303 (TT
It is checked whether or not it is the first time-out of J.Q.931 (decision 103).

It is time-out after the second time, and judgment 1
When the result of step 03 is NO, a release completion message REL_COMP is sent to ISDN, and the call connection operation at that time is disconnected from the terminal itself (process 112). At this time, it has been found that the cause of the call disconnection is a timeout on the own terminal side, and the state value indicating the state of the call setting procedure is the state number “1” indicating the calling state.
Therefore, the processing shifts to the judgment 106, and the subsequent processing is executed.

When the call is disconnected during communication for some reason, the state value at the time of receiving the disconnection message DISC indicates the state number "1" indicating the communication state.
In this case, the result of the determination 108 is NO, and the processing shifts to the processing 109, so that a recall operation with the same terminal function is performed.

If the ISDN exchange is reset for some reason, the terminal termination point identifier TEI stored on the exchange is also reset. In such a state, when a calling operation is performed from the ISDN facsimile apparatus, the ISDN facsimile apparatus makes a call using the terminal termination point identifier TEI already assigned, and the value of the terminal termination point identifier TEI is ISDN. In this case, the D-channel layer 2 does not start normally, and the calling operation at that time fails.

In this case, since the D channel layer 3 is not activated, the status number becomes “0” indicating an empty state. Therefore, in this embodiment, a fallback procedure is executed, so that a new calling operation is executed. , An appropriate recall operation can be performed.

As described above, in this embodiment, the ISDN
The fallback procedure can be activated without being affected by the specificity of the standard, the change in the standard, or the usage status (frequency) of the cause information element. Can be performed.

Further, since the condition for fallback is determined based on the state value of the state of the D channel layer 3, the fallback is applied to all call disconnections before the completion of the call connection without depending on the value of the cause information element. The procedure can be activated, and the situation in which connection is not possible can be avoided to the maximum without making the user aware of the terminal attributes, and the convenience of the terminal is improved.

By the way, in the above-described embodiment, the case where the fallback from the group 4 facsimile machine function to the group 3 facsimile machine function has been described.
For example, even when the group 3 facsimile apparatus function is used, the outgoing call parameter in which the value of the “transmission capability” information element is “3.1 KHz audio” and the value of the “higher layer compatibility” information element is “G3 facsimile” is used. There are two cases: using the calling parameter, and using the calling parameter whose value of the “transmission capability” information element is “call”. When there are two types of calling parameters with the same communication function as described above, since there is a fallback relationship between the calling parameters, the same processing as in the above-described embodiment is performed.
The call connection operation can be controlled.

Further, in the above-described embodiment, the case where the present invention is applied to an ISDN facsimile apparatus having a group 3 facsimile apparatus function, a group 4 facsimile apparatus function, and a telephone call function while using ISDN as a transmission path will be described. However, the present invention can be similarly applied to other ISDN communication terminal devices provided with a plurality of terminal functions or a plurality of call parameters in a fallback relationship.

[0081]

As described above, according to the present invention,
The fallback procedure can be started without being affected by the specificity of ISDN, the change in the standard, or the use status (frequency) of the cause information element, so that an appropriate recall operation can be performed, and communication operation can be performed. There is an effect that it can be executed properly.

Since the condition for fallback is determined based on the state value of the state of the D channel layer 3, fallback is applied to all call disconnections before the completion of the call connection without depending on the value of the cause information element. The procedure can be started, the situation in which connection is not possible can be avoided to the utmost without making the user aware of the terminal attributes, and the effect of improving the convenience of the terminal can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a timing chart showing an example of a call control procedure performed by a terminal connected to ISDN with ISDN.

FIG. 3 is a schematic diagram showing an example of a signal format of each message for ISDN call setup.

FIG. 4 is a flowchart illustrating an example of a process executed by the ISDN facsimile apparatus regarding a call connection;

[Explanation of symbols]

 1 control unit 2 system memory

Continuation of the front page F term (reference) 5C062 AA03 AA34 AB38 AC38 AE14 BA04 5C075 AA05 BA13 CD21 CE12 5K101 KK01 LL03 QQ07 QQ09 RR14

Claims (14)

[Claims] 1. An ISDN communication terminal device having a plurality of terminal functions, wherein a first terminal function is selected, and an initial call operation is performed to a specified destination in a state where the selected first terminal function is specified. If the call connection for the call fails, the second
An ISDN communication terminal device comprising: a call control unit that performs a call operation to the same destination in a state where the terminal function is selected and the selected second terminal function is specified. 2. An ISDN communication terminal device having a plurality of terminal functions, wherein a first terminal function is selected, and an initial call operation is performed to a specified destination in a state where the selected first terminal function is specified. And if the call connection for the call fails, the second terminal function is selected and the selected second terminal function is specified, regardless of the content of the reason for the failure of the call connection. 2. An ISDN communication terminal device comprising: a call control means for making a call operation to the same destination. 3. An ISDN communication terminal device having a plurality of terminal functions, wherein a first terminal function is selected, and an initial call operation is performed to a specified destination in a state where the selected first terminal function is specified. And if the call connection for the outgoing call is disconnected from ISDN, even if the content of the disconnection reason is "absent",
An ISDN communication terminal device comprising: a call control unit that performs a call operation to the same destination while selecting a second terminal function and designating the selected second terminal function. 4. An ISDN communication terminal device having a plurality of terminal functions, wherein a first terminal function is selected, and an initial call operation is performed to a specified destination in a state where the selected first terminal function is specified. If the call connection for the call is disconnected from the ISDN, the state of the local terminal user side of the D channel layer 3 that has received the disconnection message received from the ISDN is checked, and the state is determined by predetermined contents. Sometimes, the second
An ISDN communication terminal device comprising: a call control unit that performs a call operation to the same destination in a state where the terminal function is selected and the selected second terminal function is specified. 5. An ISDN communication terminal device having a plurality of terminal functions, wherein a first terminal function is selected, and an initial call operation is performed to a specified destination in a state where the selected first terminal function is specified. And if the call connection for the outgoing call fails due to a timeout on its own terminal side, the second terminal function is selected, and the same destination is specified with the selected second terminal function specified. An ISDN communication terminal device comprising call control means for making a call to a terminal. 6. An ISDN communication terminal device having a plurality of terminal functions, wherein a first terminal function is selected, and a first call operation is performed to a specified destination in a state where the selected first terminal function is specified. If the call connection for the call fails, if the content of the failure reason for the call connection is a predetermined one,
While the re-call operation is performed in a state where the first terminal function is selected, when the content of the reason for the failure of the call connection is other than a predetermined one, the second terminal function is selected, and the selected second terminal function is selected. An ISDN comprising call control means for making a call operation to the same destination with a terminal function specified.
Communication terminal device. 7. The method according to claim 1, wherein the second terminal function has a fallback relationship with respect to the first terminal function. The ISDN communication terminal device according to claim 5 or 6. 8. An ISDN with a plurality of calling parameters.
The communication terminal device selects a first calling parameter, performs an initial calling operation to a specified destination in a state where the selected first calling parameter is specified, and establishes a call connection for the calling. In the case of failure, a call control means is provided for selecting a second call parameter and performing a call operation to the same destination in a state in which the selected second call parameter is specified. I
SDN communication terminal. 9. An ISDN with a plurality of calling parameters
The communication terminal device selects a first calling parameter, performs an initial calling operation to a specified destination in a state where the selected first calling parameter is specified, and establishes a call connection for the calling. In the case of failure, regardless of the content of the reason for the failure of the call connection, the second call parameter is selected, and the call operation to the same destination is performed with the selected second call parameter specified. An ISDN communication terminal device comprising a call control means for performing a call control. 10. ISD with multiple calling parameters
In the N communication terminal device, a first call parameter is selected, a first call operation is performed to a specified destination in a state where the selected first call parameter is specified, and a call connection for the call is performed. Is disconnected from ISDN, the reason for the disconnection is “absent”
Even in this case, there is provided a call control means for selecting a second calling parameter and performing a calling operation to the same destination in a state where the selected second calling parameter is designated. ISDN communication terminal. 11. An ISD with a plurality of calling parameters
In the N communication terminal device, a first call parameter is selected, a first call operation is performed to a specified destination in a state where the selected first call parameter is specified, and a call connection for the call is performed. Is disconnected from the ISDN, the state of the local terminal user side of the D channel layer 3 which has received the disconnection message received from the ISDN is checked, and when the state has a predetermined content, the second call parameter is changed. A call control means for making a call to the same destination in a state in which the call is selected and the selected second call parameter is specified.
SDN communication terminal. 12. ISD with multiple calling parameters
In the N communication terminal device, a first call parameter is selected, a first call operation is performed to a specified destination in a state where the selected first call parameter is specified, and a call connection for the call is performed. However, in the case of failure due to a timeout on its own terminal side, call control for selecting a second calling parameter and performing a calling operation to the same destination with the selected second calling parameter specified An ISDN communication terminal device comprising means. 13. An ISD with a plurality of calling parameters
In the N communication terminal device, a first call parameter is selected, a first call operation is performed to a specified destination in a state where the selected first call parameter is specified, and a call connection for the call is performed. Fails, if the content of the reason for the failure of the call connection is a predetermined one, the re-call operation is performed with the first calling parameter selected, while the content of the reason for the failure of the call connection is The call control means for selecting a second calling parameter and performing a calling operation to the same destination in a state where the selected second calling parameter is designated. ISDN communication terminal device characterized by the above-mentioned. 14. The method according to claim 8, wherein the second calling parameter has a fallback relationship with respect to the first calling parameter. 14. The ISDN communication terminal device according to claim 12 or claim 13.