JP3043107B2 - Facsimile signal transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile signal transmission system for transmitting a facsimile signal in accordance with a predetermined control procedure in a transmission device for interfacing a digital signal line with an analog signal type facsimile device.

[0002]

2. Description of the Related Art GIII facsimile apparatuses have been widely used because high-speed transmission is possible by adopting a redundancy suppression coding method, and a direct connection to an existing subscriber line is possible. A signal transmitted and received by such a facsimile apparatus during communication is an analog signal, and a transmission system for transmitting and receiving the signal via a digital line has been proposed (Japanese Patent Application No. Sho 62).
-206940).

FIG. 9 is a diagram showing a configuration example of a conventional facsimile signal transmission system. In the figure, the facsimile device 91 ₁ is connected to one end of the digital line through the transmission device 92 _1, the other end of the digital line is connected to the facsimile device 91 ₂ via the transmission unit 92 _2.
Further, telephones 93 ₁ and 93 ₂ are connected in parallel to the facsimile machines 91 ₁ and 91 ₂ , respectively.

[0004] In such a method, for example, in the case of sending facsimile signals (command) from the facsimile apparatus 91 ₁ to the facsimile device 91 _2, the transmission device 92
₁ demodulates the command using a modem, converts the command to a digital signal, and sends the digital signal to a digital line. The transmission device 92 _2, again modulates the digital signal by using a modem, facsimile machine 9 converts the original analog signal
Give 1 to ₂ . Further, the transmission devices 92 ₁ and 92 ₂ are connected to the telephone 9 when facsimile communication is not being performed.
A standby state is established in a voice communication mode in which voice signals can be transmitted and received between the 3 ₁ and 93 ₂ via a digital line.

[0005]

By the way, in such a conventional system, each transmission device is a facsimile device 9.
When a failure occurs in a digital line or the like during transmission and reception of a facsimile signal between 1 ₁ and 91 _2, there is no means for detecting the failure and promptly restoring the state before the start of communication (voice communication mode). However, there has been a state mismatch between the transmission device and the facsimile device. Further, even if a new facsimile call occurs after the occurrence of such a failure, the communication procedure of the call is often interrupted because the transmission device has not been restored to the state before the start of communication. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a facsimile signal transmission system capable of promptly resolving a state mismatch between a transmission device and a facsimile device caused by an abnormal interruption of a communication control procedure.

[0007]

FIG. 1 is a block diagram showing the principle of the present invention. A facsimile apparatus 11 for transmitting and receiving analog facsimile signals
In a facsimile signal transmission system including a facsimile apparatus 11 and a transmission apparatus 13 for interfacing with a digital line, a time until a response signal to the facsimile signal is transmitted from the facsimile apparatus 11 to be interfaced is monitored. When the time exceeds the maximum response time allowed for the call of the facsimile apparatus 11, the transmission apparatus 13 is provided with control means 15 for starting the call disconnection processing by the transmission apparatus 13.

According to a second aspect of the present invention, in the first aspect of the invention, the control means 15 causes the transmission device 13 to repeatedly transmit an analog facsimile signal at a predetermined cycle, and the number of times of the repeated transmission is reduced. It is characterized by including means for activating a call disconnection process when a predetermined value is exceeded. According to a third aspect of the present invention, in the first aspect of the present invention, the control means 15 monitors an error of the digital signal received via the digital line, and calls the transmission device 13 in response to the error. A means for starting the disconnection processing.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the control means 15 transmits to the transmission apparatus 13 in response to a disconnection command signal received from one of the digital line and the facsimile apparatus 11. It is characterized by including means for initiating a call disconnection process.

[0010]

According to the first aspect of the present invention, if the facsimile apparatus 11 does not transmit a response signal to the facsimile signal transmitted from the transmission apparatus 13 within the maximum response time, the control means 15 disconnects the call. The transmission apparatus 13 is activated, and the transmission apparatus 13 stops sending signals to the digital line and the facsimile apparatus 11 which interfaces with the digital line.

The facsimile apparatus 11 and the transmission apparatus and the facsimile apparatus which are opposed to each other via the digital line can individually detect the above-mentioned signal transmission stop and perform the call disconnection processing. To the state of. According to the second aspect of the present invention, if the facsimile apparatus 11 does not transmit a response signal to the facsimile signal transmitted from the transmission apparatus 13 within a predetermined time, the control unit 15 transmits the same signal to the transmission apparatus 13 at a predetermined cycle. A facsimile apparatus 1 for repeatedly transmitting a facsimile signal
It is confirmed a plurality of times whether or not 1 is in a no-response state.

Therefore, when the facsimile apparatus 11 does not respond exactly, the transmission apparatus 13 operates similarly to the facsimile apparatus 11 and the facsimile apparatus and the transmission apparatus which face each other via the digital line. The device can be quickly restored to the state before the start of communication. According to the third aspect of the present invention, when there is an error in the digital signal received via the digital line, the control unit 15 causes the transmission device 13 to start a call disconnection process corresponding to the digital line.

Therefore, even when a transmission error occurs on a digital line, the transmission device 13 quickly transmits the transmission device and the facsimile device which are opposed to each other via the digital line in the same manner as in the first aspect. It can be restored to the state before the start of communication. According to the fourth aspect of the present invention, the control unit 15 causes the transmission device 13 to start a disconnection process in response to a disconnection command signal received from any of the facsimile device 11 and the digital line.

Therefore, the transmission device 13 can be connected to the opposite transmission device via a digital line in the same manner as in the first aspect of the invention, regardless of the interruption of the communication procedure in any of the facsimile devices communicating with each other. Further, the facsimile apparatus can be promptly restored to the state before the start of communication.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a diagram showing one embodiment of the present invention. In the drawing, components having the same functions and configurations as those shown in FIG.
Here, the description is omitted.

[0016] The facsimile device 91 ₁ and telephone 93
_1, the transmission device 21 _1, the facsimile device via the digital line and the transmission device 21 ₂ 91 ₂ and telephone 9
3 is connected ₂ to. Transmission apparatus 21 ₁ is composed of a transmitter 22 ₁ and the receiver 23 _1, the transmission apparatus 21 ₂ is comprised of the transmission unit 22 ₂ and the reception section 23 _2. The configuration of the transmission device 21 _2, since it is the same as the transmission device 21 _1, omitting the detailed configuration in FIG. 2, in the subscript numbers given the same reference numbers as _"2" or less represents each component corresponding to the transmission device 21 _2, the description thereof is omitted.

Transmission section 22₁Then, the facsimile machine 91
₁Is output from the A / D converter 24. ₁, Demodulator 25₁You
And switching control unit 26₁Given to. A / D converter
24 ₁Output from the audio encoder 27₁Selector through
28₁To one input. Demodulator 25₁Output
Is the command reception processing unit 29₁Connected to one of its outputs
Power is selector 28₁Connected to the other input of the
The force is the switching control unit 26₁Is connected to the control input. Off
Switching control unit 26₁Output of selector 28₁Selection control
Applied to the input, the output of which is connected to the digital line.
You.

Receiver 23₁Now, receive from the digital line
The received signal is transmitted to the speech decoder 30. ₁, Command transmission processing
Department 31₁And switching control unit 32₁Given to.
Voice decoder 30₁Output of the D / A converter 33₁Through
Selector 34₁Connected to one of the inputs. command
Transmission processing unit 31₁One output of the modulator 35₁Through
Selector 34₁Connected to the other input of the
Facsimile machine 91₁And telephone 93₁Connected to
You. Command transmission processing unit 31₁The other output of is switched
Control unit 32₁Is connected to the control input of the
TA 34₁To the selection control input.

Further, the command reception processing unit 29 ₁ of the transmitting unit 22 ₁ is interconnected with the command transmission processing unit 31 ₁ of the receiver 23 _1. FIG. 3 is a diagram illustrating a configuration of the command reception processing unit and the command transmission processing unit. In the figure,
The command receiving section 29 _1, the output of the demodulator 25 ₁ is supplied to the command detection section 41 _1, its first output is provided to the command relay transmission unit 42 _1. The first output of the command relay transmitting unit 42 ₁ is connected to the other input of the selector 28 ₁ , and the second output is connected to the control input of the switching control unit 26 ₁ . The second output of the command detection section 41 ₁ a first timer circuit 43 ₁ and the second timer circuit 44
Connected to _one, the output of these timer circuit is connected to the command relay transmission unit 42 _1. The third output of the command detection section 41 ₁ is the third timer circuit 45 ₁ and the counter 4
Is connected to _61, the output of the third timer circuit 45 ₁ is connected to a counter 46 _1. One output of the counter 46 ₁ is connected to the command relay transmitting section 42 ₁ .

Command transmission processing unit 31₁So, digital
Line is the command relay receiving unit 47₁Connected to the input of
The first output is the command transmission unit 48₁Connected to.
Command relay receiving unit 47₁The second output of the switching system
Gobu 32₁Is connected to the control input. Command relay reception
Part 47₁The third output of the command reception state determination unit 49 ₁
And its output is sent to the command transmitting unit 48₁Connected to
It is. Command transmission unit 48₁The first output of the modulator 3
5₁Connected to.

Further, between each other and the command reception processing unit 29 ₁ and the command transmission processing unit 31 _1, the command relay transmission unit 42 ₁ is interconnected with the command relay-receiving unit 47 _1. The second output of the command transmitting unit 48 ₁ is connected to the first timer circuit 43 ₁ and the second timer circuit 44 _1,
A third output is connected to the third timer circuit 45 _1. The other output of the counter 46 ₁ is connected to the command transmitting unit 48 _1.

[0022] As to the correspondence relationship between the block diagram shown in this embodiment and FIG. 1, the facsimile device 91 ₁ corresponds to the facsimile apparatus 11, A / D converter 24 _1, the speech encoder 27 _1, demodulates Unit 25 ₁ , switching control unit 2
6 ₁ , a selector 28 ₁ , an audio decoder 30 ₁ , a D / A converter 33 ₁ , a modulator 35 ₁ , a switching control unit 32 ₁ and a selector 34 ₁ correspond to the transmission device 13 and a command reception processing unit 29 ₁ and command transmission processing unit 31 ₁ corresponds to the control means 15.

Hereinafter, this embodiment will be described with reference to FIGS.
Will be described. The configuration of the present invention is characterized by:
Communication protocol control method for facsimile calls
To transmit facsimile signals over digital lines.
The configuration of the system is the same as that of the conventional example.
The description is omitted. Transmission unit 22₁Now, switching control
Part 26₁Of the signal given from the facsimile machine side
Detects the type and determines whether facsimile communication is in progress
Then, a selection signal according to the result of the determination is transmitted. SEREC
TA 28₁Responds to such a selection signal by facsimile
If the re-communication is not in progress, the speech encoder 27₁Select output
And connect to a digital line. The receiving unit 23₁
Then, the switching control unit 32₁Is via a digital line
In the same way, a selection signal is transmitted according to a given signal, and the
The D / A converter 33 when no communication is being performed.₁Out of
Select power and telephone 93 ₁Connect to Such a state
In the (voice communication mode), the telephone 93₁And digital times
Audio signals can be transmitted to and received from the line.

Further, for example, when the facsimile device 91 ₁ transmits to the facsimile device 91 _2, the facsimile via a facsimile device 91 ₁ transmission device 21 _1, the digital line and the transmission device 21 ₂ 91
_A call signal is sent to 2 (FIG. 4). Facsimile apparatus 91 ₂ which detects the call signal sends a digital identification signal DIS indicating the function to the transmission device 21 ₂ (FIG. 4).

[0025] In the transmission device 21 _2, the demodulator 25 _2, giving this way a digital identification signal DIS supplied by converting the digital signal to the command reception processing section 29 _2. The command receiving section 29 _2, the command detector 41 ₂ command relay transmission section the digital signal 42
Through the _two give to the selector 28 _2. On the other hand, switching control unit 26 ₂ gives a selection signal corresponding to the type of the signal by detecting a digital identification signal DIS above (whether it is a facsimile signal and the audio signal) to the selector 28 _2. The selector 28 _2, according to the selection signal supplied in this way, sends a digital identification signal DIS, which is converted into a digital signal to a digital line.

On the other hand, the transmission device 21₁Now, the digital times
The digital identification signal DIS received via the line
Command transmission processing unit 31_TwoCommand relay receiver
47 ₁And command transmission unit 48₁Modulator 35 via
₁Sent to Modulator 35 ₁Gives in this way
The obtained digital signal is converted to the original digital identification signal DIS.
Convert to The switching control unit 32₁Is a digital
Digital identification signal DIS received via the
The selector 3 detects the signal and selects a selection signal according to the type of the signal.
4₁Give to. Therefore, the recovered digital identification
The signal DIS is supplied to the selector 34₁Via facsimile
Place 91₁Given to.

[0027] The transmission of such facsimile signal is omitted, since the same manner performed between the transmission apparatus 21 _1, 21 ₂ mutually for the other facsimile signal (command), and that the description thereof will be omitted. By the way, in the transmission device 21 ₁ , the command transmitting section 48 ₁ sends the digital identification signal DIS received via the digital line to the modulator 35 ₁ , and outputs the digital identification signal DIS from the command receiving state determining section 49 ₁ . The first timer circuit 43 ₁ (interval length = 35 seconds ± 5 seconds) is started in response to the reception completion notification (FIG. 4). Further, the command transmitting unit 48 ₁ monitors the notification information given through the command detector 41 ₁ and the command reception state determining unit 49 ₁ is sent in response from the facsimile apparatus 91 ₁ into a digital identification signal DIS above Digital command signal DCS (used for notification of search line density, coding method and other selected functions)
When the signal is not received within a predetermined time, the transmitted digital identification signal DIS is repeatedly transmitted in a 3-second cycle (FIG. 4).

However, even if such repetitive transmission is performed, 35
When the digital command signal DCS within seconds ± 5 seconds is not received, the first timer circuit 43 ₁ sends a time-out signal. Command relay transmission unit 42 ₁ requests the restoration of the audio communication mode switching control section 26 ₁ in response to such a time-out signal, and sends the time-out signal to the command relay-receiving unit 47 _1. Command relay-receiving unit 47 ₁ requests the restoration of the audio communication mode switching control section 32 ₁ in response to the timeout signal. The switching control units 26 ₁ and 32 ₁ send selection signals to the selector circuits 28 ₁ and 34 ₁ in response to the above-mentioned request,
The voice communication mode is set (FIG. 4). On the other hand, in the transmission apparatus 21 ₂ detects this with the command relay-receiving unit 47 ₂ since the transmission device 21 ₁ is a facsimile signal is not received when restored to the voice communication mode, to the voice communication mode switching control section 32 ₂ sends a recovery request, and switched via the command relay transmission unit 42 ₂ controller 26 ₂
Make the same request. The switching control units 32 ₂ and 26 ₂
It sends a selection signal to the selector circuit 34 _2, 28 ₂ in response to the above request, and sets the voice communication mode (FIG. 4
).

It should be noted, the facsimile device 91 _1, also the first timer circuit 43 ₁ is not be restored to the state before starting communication when sending the timeout signal, the transmission apparatus 21
_{When 1} is restored to the voice communication mode, no facsimile signal is received, so that the state before the start of communication (voice communication mode) is restored. When the facsimile machine 93 ₁ normally receives the above-mentioned digital identification signal DIS, it sequentially sends out a digital command signal DCS, a training signal and a training check signal TCF. The transmission device 21 ₁ transmits to the transmission device 21 ₂ via the digital line one after another of these signals.

The facsimile apparatus 91 ₂ receives the training check signal TCF received in this manner.
In response to (FIG. 5), a reception preparation confirmation signal CFR and other pre-message response signals are transmitted. In the transmission device 21 ₁ receives the pre-message response signal, the command transmitting unit 48 ₁ sends the signal to the facsimile apparatus ₉₃₁ side and the reception completion notification of the signal supplied from the command receiving state determination unit 49 ₁ , The second timer circuit 44 ₁ (interval length = 6 ± 1 second) is started (FIG. 5).

The facsimile device 91 ₁ in response to the pre-message response signals described above the following commands (e.g., a training signal) when sending a command detection unit ₄₁₁ detects the command, the command reception state determining unit 49 ₁ The reception completion of the command detected in this way is recognized, and a reception completion notification is transmitted. The command transmission unit 48 ₁
Its second timer circuit 44 ₁ is stopped in response to the notification. However, when the above command is not received within a 6 ± 1 seconds, the second timer circuit 44 ₁ sends a time-out signal, the transmission apparatus 21 _1, 21 ₂ is controlled procedure described above in accordance with the time-out signal In the same manner as described above, the state is restored to the state before the start of communication (FIG. 5).

Furthermore, the facsimile device 93 _1, the multi-page signal MPS for each delivery unit of the image signal, and sends the message end signal EOM, a procedure end signal EOP other post-message command (Fig. 6), these signals are transmitted 21 ₁ and through the trunk line is transmitted to the transmission device 21 _2. In the transmission device 21 ₂ , the command transmission unit 48 ₂
But transmits the post mail message command to the facsimile apparatus 91 ₂ through a modulator 35 ₂ (FIG. 6), and in response to receiving notification of completion of the instruction given from the command receiving state determination unit 49 _1, the third The timer circuit 45 ₁ (interval length = 3 seconds) is started. Facsimile machine 91 ₂
When but it sends a message confirmation signal MCF other signals in response to the post-message instruction described above, the command transmitting unit 48 _2, of the signal by the notification given via the command detector 41 ₂ and the command reception state determination unit 49 ₂ It recognizes the reception completion, the third timer circuit 45 ₂ is stopped to reset the counter 46 _2. However, if the confirmation signal is not received within three seconds, the third timer circuit 45 ₂ sends a time-out signal, the counter circuit 46 ₂ is above the command transmission unit 48 ₂ counts the time-out signal Request resending of post messages. Command transmission unit 48 ₂ retransmits the already transmitted post messages in response to the request (Fig. 6) is, when the number of retransmissions exceeds a predetermined value, the counter 46 ₂ is above the time-out signal to the command relay transmission unit 42 ₂ give. Transmission device 21 _2, the time-out signal applied in this manner, restored to the state before starting communication in the same manner as the control procedure described above (FIG. 6), the transmission device 21 ₁ may communicate prior to the start and following this (FIG. 6).

Further, for example, in the transmission device 21 _2,
A facsimile signal (command) received via a digital line is accompanied by a CRC error and other errors (FIG. 7).
) In this case, the command relay-receiving unit 47 ₂ detects the channel error switching control unit 32 ₂ sends a recovery request to the voice communication mode, and switching control unit 26 via the command relay transmission unit 42 ₂ Send the same request to ₂ . Transmission device 21 _2, in this way recover to a voice communication mode above in (7), followed by the transmission device 21 ₁ is also restored to the voice communication mode (Fig. 7).

Further, for example, due to some cause,
Kushimiru 93₁Sends disconnection command signal DCN
(FIG. 8) and the transmission device 21₁Now, command relay transmission
Part 42 ₁Switch according to the disconnect command signal DCN
Control unit 26₁Sends a request to restore to voice communication mode to
And the command relay receiving section 47₁Switching control unit via
32₁A request for restoration to the voice communication mode is also sent. one
, The transmission device 21_TwoThen, the command transmission unit 48_TwoIs
Command line receiving unit 47 from digital line_TwoReceived via
The disconnection command signal DCN (FIG. 8)
Facsimile machine 91_Two(FIG. 8). command
Relay receiving section 47₁Is applied to such a disconnect command signal DCN.
Switching control unit 32 according to₁To voice communication mode
Sends a request and sends the command₁Through
Switching control unit 26₁Also sends the same request. But
The transmission device 21₁, 21_TwoIs the control procedure described above.
Similarly, the communication is restored to the state before the start of communication (FIG. 8,
).

As described above, according to the present embodiment, even if a failure occurs in the digital line, the facsimile apparatus, and the transmission apparatus during communication, the facsimile apparatus and the transmission apparatus can be quickly restored to the state before the start of communication. Can be. In this embodiment, the configurations of the command reception processing unit and the command transmission processing unit are realized by hardware as shown in FIG. 3, but the present invention is not limited to such a configuration. Some or all of them can be realized by software control using a processor or the like.

The interval length of the timer circuit and the count value of the counter used in this embodiment can be arbitrarily determined, but the response characteristics of the connected facsimile apparatus, the delay of the transmission apparatus and the digital line In consideration of time and the like, an optimum value may be set based on "CCITT recommendation for document facsimile transmission procedure in general switched telephone network".

Further, among the signals transmitted / received by the facsimile apparatus in opposition to the transmission apparatus, those used as criteria for restoring to the voice communication mode are described above by way of example and are not limited thereto. For example, for the digital command signal DCS, the transmitting terminal identification signal T
The SI and other reception command signals can be similarly determined, and the message confirmation signal MCF can be similarly determined by the retraining acknowledgment signal RTP and other post message response signals.

Further, in the present embodiment, the operation has been described as an example of the protocol control procedure in the case of transmitting a call, but the present invention is similarly applicable to the case of receiving a call.

[0039]

As described above, according to the present invention, the facsimile apparatus becomes unresponsive during communication for some reason, recovers to the state before the start of communication, or receives a signal received via a digital line. Is wrong,
A facsimile apparatus that communicates via a digital line and a transmission apparatus disposed between the facsimile apparatus and the digital line can be promptly restored to a state before the start of communication. Therefore, even if the communication procedure of the facsimile call is interrupted, the state inconsistency between the facsimile apparatus and the transmission apparatus caused by this in the conventional example can be quickly resolved.

[Brief description of the drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a diagram showing one embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a command reception processing unit and a command transmission processing unit.

FIG. 4 is a diagram illustrating an operation when a digital command signal DCS is not received.

FIG. 5 is a diagram illustrating an operation when a control signal according to a pre-message response signal is not received.

FIG. 6 is a diagram illustrating an operation when there is no response to a post-message instruction;

FIG. 7 is a diagram illustrating an operation when an error occurs on a digital line.

FIG. 8 is a diagram illustrating an operation according to a disconnection command signal.

FIG. 9 is a diagram showing a configuration example of a conventional facsimile signal transmission system.

[Explanation of symbols]

11 facsimile apparatus 13 the transmission device 15 control means 21 _1, 21 _2, 92 _1, 92 ₂ transmission device 22 _1, 22 ₂ transmitting unit 23 _1, 23 ₂ reception unit 24 _1, 24 ₂ A / D converter 25 _1, 25 ₂ demodulators 26 ₁ , 26 ₂ , 32 ₁ , 32 ₂ switching control sections 27 ₁ , 27 ₂ voice encoders 28 ₁ , 28 ₂ , 34 ₁ , 34 ₂ selectors 29 ₁ , 29 ₂ command reception processing section 30 ₁ , 30 ₂ voice decoder 31 ₁ , 31 ₂ command transmission processing unit 33 ₁ , 33 ₂ D / A converter 35 ₁ , 35 ₂ modulator 41 ₁ , 41 ₂ command detection unit 42 ₁ , 42 ₂ command relay transmission unit 43 _1, 43 ₂ first timer circuit 44 _1, 44 ₂ second timer circuit 45 _1, 45 _{2 1} third timer circuit 46, 46 _second counter 47 _1, 47 ₂ command relay-receiving unit 48 _1, 48 ₂ command Transmitter 49 ₁ , 49 ₂ frames Receiving state determination units 91 ₁ and 91 ₂ facsimile machines 93 ₁ and 93 ₂ telephones

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI H04N 1/32 H04L 13/00 309A (72) Inventor Hideki Mori 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Fujitsu Limited (72 ) Inventor Sumiko Kido 1-8 Oyamacho, Kanazawa City, Ishikawa Prefecture Inside Fujitsu Hokuriku Communication System Co., Ltd. (56) References JP-A-2-243033 (JP, A) JP-A-2-241175 (JP, A) JP-A-62-45239 (JP, A) JP-A-4-45656 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/00 H04N 1/32

Claims (4)

(57) [Claims] 1. A facsimile signal transmission system comprising: a facsimile apparatus for transmitting and receiving an analog facsimile signal; and a transmission apparatus for interfacing the facsimile apparatus with a digital line. Control means for monitoring a time until a response signal to the signal is transmitted, and when the time exceeds a maximum response time allowed for the call of the facsimile apparatus, the transmission apparatus starts the call disconnection processing. The above transmission equipment
Facsimile signal transmission method characterized by comprising the location. 2. The invention according to claim 1, wherein the control means causes the transmission device to repeatedly transmit an analog facsimile signal at a predetermined cycle, and, when the number of times of repetition exceeds a predetermined value, causes the transmission device to transmit the call. A facsimile signal transmission method comprising means for initiating a disconnection process. 3. The invention according to claim 1, wherein the control means monitors an error in the digital signal received via the digital line, and activates a call disconnection process in the transmission device in response to the error. A digital signal transmission method characterized by including means. 4. The invention according to claim 1, wherein the control means includes means for initiating a call disconnection process in the transmission device in response to a disconnection command signal received from one of a digital line and a facsimile machine. A digital signal transmission method characterized by the above-mentioned.