JP2001257807A - Line connection device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable line connection between an inexpensive general-purpose private branch exchange and a switching network. SOLUTION: A circuit connection between a private branch exchange and a circuit network.
Switch means for shutting off, an MSK modem for demodulating and generating an MSK signal, and the equipment to be exchanged are telephones T1 to T1.
At the time of Tn, the MSK modem is caused to send a line cut-off advance notification signal to the line network prior to the end signal, and the line cut-off advance notification signal sent from the line network is detected based on the demodulated signal of the MSK modem. In the line connection device comprising a control unit that causes the switch means to perform line disconnection at a time, when the control unit continuously detects the facsimile device identifiable signal included in the demodulated signal at least twice, The device to be exchanged is determined as a facsimile device, and when no facsimile device identifiable signal is detected, the device to be exchanged is determined as a telephone, and the line is interrupted to the switch means at the time of detection of the line interruption advance notification signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line connection device for connecting a line between a private branch exchange to which a device to be exchanged is connected and a line network, and more particularly, to a switching device connected to a line network via a private branch exchange. The present invention relates to a line connection device that performs a predetermined process according to the type of a device to be processed.

[0002]

2. Description of the Related Art A communication system S1 shown in FIG. 3 is conventionally known as a communication station provided with such a line connection device. This communication system S1 is a communication station TS shown in FIG.
And a plurality of communication stations TS (not shown) having substantially the same configuration as the communication station TS. Each communication station TS
Are the line connection device 21, the private branch exchange 22, and the radio 3
It is provided with. In this case, the private branch exchange 22 includes n telephones T1 to Tn, which are devices to be exchanged.
(Hereinafter referred to as "telephone T" when not distinguished)
Similarly, m facsimile apparatuses (facsimile apparatuses) F1 to Fm (hereinafter, referred to as “fax apparatus F” when not distinguished) are connected as exchange target apparatuses. The private branch exchange 22 has a built-in memory in which correspondence data indicating the correspondence between the line numbers (telephone numbers and FAX numbers) of these exchange target devices and their types is stored in advance. And 4 wire lines 4WS, 4WR
And exchange processing for connecting to the server.

On the other hand, the line connection device 21 includes a control unit 31
And D for encoding and decoding the DTMF signal
A TMF encoder / decoder 12, a secret device 13 used for telephone communication, and four switch circuits 14a to 14a.
The switch 14 includes a changeover switch 14 that is controlled by a control signal SC1 and an analog switch 15 that is on / off controlled by a control signal SC2, and an MSK modem 16 that encodes and decodes an MSK signal. I have. This line connection device 21 is a four-wire line 4WS, 4WR between the private branch exchange 22 and the wireless device 3.
The connection / disconnection control of the communication device, transmission / reception of a dial signal by an MSK signal, connection / disconnection of the secret device 13 and the like are executed.

In this communication station TS, for example, when there is a call from the facsimile apparatus F, first, the private branch exchange 22 determines the type of the exchange processing target device that has made the call based on the correspondence data in the internal memory. Then, the SS signal is output to the control unit 31 of the line connection device 21. Next, the private branch exchange 22
Is a type signal S indicating the type of the exchange target device that made the call.
K is output to the control unit 31 of the line connection device 21 and
The DTMF signal output from the FAX device F is output to the DTMF encoder / decoder 12 in the line connection device 21. Next, the DTMF encoder / decoder 12
The TMF signal is converted into binary digital number data and output to the control unit 31. On the other hand, the control unit 31
Based on K, the type of the calling exchange target device is determined (in this case, it is determined that the device is a facsimile device), and a transmission control signal PTT is output to the wireless device 3 so that the transmitting unit in the wireless device 3 is transmitted. Start. Next, the control unit 31
Transfers the digital number data to the MSK modem 16 to generate the number data based on the MSK signal and output it to the 4-wire line 4WS. Thereby, the wireless device 3 transmits the wireless signal modulated with the MSK signal at the frequency f1. Next, the control unit 31 controls the analog switch 15 to be on by outputting the control signal SC2 while maintaining the disconnection state of the secret device 13 between the four-wire lines 4WS and 4WR. As a result, the fax machine F on the calling side and the wireless device 3 are connected to the 4-wire circuit 4WS,
They are interconnected by 4WR. The control unit 31
Is determined based on the type signal SK, when the type of the exchange-target device to be called is determined to be the telephone set T, the control signal SC1
Is output to control the changeover switch 14, thereby connecting the secret device 13 between the 4-wire lines 4WS and 4WR.

On the other hand, at the communication station TS on the receiving side, the radio 3
Receives the radio signal, demodulates it into an MSK signal,
The K signal is output to the line connection device 21 and the incoming signal SQ is output to the control unit 31 in the line connection device 21. Next, the MSK modem 16 in the line connection device 21
The K signal is converted into binary digital number data and output to the control unit 31. Subsequently, the control unit 31 transfers the digital number data to the DTMF encoder / decoder 12 and outputs an SS signal to the private branch exchange 22. Thereafter, the DTMF encoder / decoder 12 outputs a DTMF signal obtained by encoding the digital number data to the private branch exchange 22. Next, the private branch exchange 22 checks the DTM
The FAX device F corresponding to the dial number based on the F signal is called, the SS signal is output to the control unit 31 in response to the FAX device F, and the exchange target device is referred to by referring to the correspondence data in the built-in memory. After determining the type, a type signal SK is output to the control unit 31. Thereby, the control unit 31 determines the type of the exchange target device (in this case, determines that the device is a facsimile device), and
3 while maintaining the disconnection state between the 4-wire lines 4WS and 4WR, outputting the control signal SC2 to control the analog switch 15 to the on state, and outputting the transmission control signal PTT to transmit the radio signal 3 Activate the transmitter in In this state, the FAX device F is connected to the wireless device 3 via the four-wire lines 4WS and 4WR, and as a result, the FAX device F on the transmitting side and the FAX device F on the receiving side are connected to each other via the wireless line. You. Also, at this time, when the control unit 31 determines that the type of the exchange-target device to be called is the telephone T based on the type signal SK, the control unit 31 outputs the control signal SC1 to perform switching control of the changeover switch 14. Thus, the secret talker 13 is connected between the 4-wire lines 4WS and 4WR.

[0006] Thereafter, at the end of the call, for example, F
The AX device F transmits a message end signal to the FAX device F on the receiving side, so that both F of the two communication stations TS and TS can receive the message end signal.
Each of the AX devices F and F goes on-hook. Next, both private branch exchanges 22 of both communication stations TS and TS are connected to the facsimile apparatus F.
After the end call is recognized by the on-hook of
Output of the SS signal to each of the CPUs is stopped. As a result, both control units 31 output the control signal SC2 to switch the analog switch 15 to the off state, thereby disconnecting the lines.

In the communication between the telephones T and T, if one telephone T is on-hook, since the communication system S1 is connected to each other via a wireless line, no end signal is sent. It is difficult for the other telephone T to reliably determine the on-hook state. For this reason, in this communication system S1, when one telephone T is hooked on, the on-hook side private branch exchange 22 stops outputting the SS signal to the control unit 31. Subsequently, the control section 31 outputs the digital call termination data to the MSK modem 16 so that the MSK modem 16 converts the data into an MSK signal and outputs a 4-wire line 4WS.
To send to. In this case, the end signal by the MSK signal is
For example, it is composed of a combination of a 1200 Hz tone and a 1800 Hz tone. For this reason, when the end signal is emitted from the receiver of the telephone set T of the other party, it is quite annoying. Therefore, in this communication system S1,
Prior to the end-of-call signal, a pre-interruption notification signal composed of a continuous tone of 1800 Hz that does not cause harshness is transmitted.

More specifically, the control unit 31 outputs a digital data cut-off advance notice signal, thereby controlling the MSK.
To the modem 16, a pre-interruption notification signal by an MSK signal consisting of a continuous tone of 1800 Hz is sent to the 4-wire line 4.
Output to WS. After that, the control unit 31 outputs an end signal of the digital data, thereby causing the MSK modem 16 to output an end signal of the MSK signal to the 4-wire line 4WS. As a result, the pre-interruption notification signal by the MSK signal is input to the control unit 31 of the other party via the MSK modem 16 of the other party. At that time, the control unit 31 outputs a control signal SC2 to control the analog switch 15 to be turned off, thereby cutting off the line. Next, the control unit 31 maintains the OFF state of the analog switch 15 and stops the output of the SS signal to the private branch exchange 22 when the call end signal is transmitted thereafter. As a result, the private branch exchange 22 outputs an end signal to the telephone set T of its own station. As a result, the other party can reliably determine the end without hearing an unpleasant end signal, and the communication station TS can surely cut off the line.

[0009]

However, the conventional communication system S1 has the following problems. That is,
In the communication system S1 using this kind of wireless network or a private wired network, when the type of the exchange processing target is the telephone T, the control unit 31 of the line connection device 21
The private branch exchange 22 outputs a type signal SK indicating the type of the device to be exchanged to the line connection device 21 in order to perform a process of generating a line disconnection advance notification signal to the modem 16 and to perform on / off control of the analog switch 15. There is a need to. For this reason, in the communication system S1, since the correspondence data indicating the correspondence between the line number of the device to be exchanged and its type must be stored in the internal memory of the private branch exchange 22 in advance, It becomes difficult to use a general-purpose private branch exchange in which the switching connection of the target device can be performed only to the public switched network. As a result, a dedicated private branch exchange 22 must be used only for the communication system.
As a result, there is a problem that the cost of the communication system S1 is increased. In particular, when constructing the communication system S1 using the communication station TS in which the general private branch exchange is already installed, the general private branch exchange is replaced with the dedicated private branch exchange 2
It has to be exchanged for 2, which is very uneconomical.

The present invention has been made in view of such a problem, and has as its main object to provide a line connection device capable of connecting a line between an inexpensive general-purpose private branch exchange and a switching network.

[0011]

According to a first aspect of the present invention, there is provided a line connecting apparatus for performing a switching process on a switching target device including a telephone and a facsimile apparatus, and a line between a private branch exchange and a line network. Switch means for performing connection and line disconnection; MSK modem for demodulating an MSK signal transmitted from the line network and generating an MSK signal to be transmitted to the line network; In response to this, prior to the end-of-call signal, a line disconnection advance notification signal is transmitted to the line network, and when the line disconnection advance notification signal transmitted from the line network is detected based on the demodulated signal of the MSK modem, A line connection device having a control unit for performing line disconnection, wherein the control unit includes a facsimile device included in a demodulated signal of the MSK modem. When the device identification signal is detected at least twice consecutively, the type of the device to be exchanged is determined as a facsimile device, and when the signal capable of identification of the facsimile device is not detected continuously, the type of the device to be exchanged is set to the telephone. And the line is cut off to the switch means at the time of detection of the line cut advance notification signal.

According to a second aspect of the present invention, there is provided a line connection device.
In the above described line connection apparatus, the facsimile apparatus identifiable signal is a transfer signal in a process of establishing a connection by the facsimile apparatus. Note that the transfer signal in the process of establishing the connection includes a DIS signal, an NSF signal, and the like.

According to a third aspect of the present invention, there is provided a line connection device.
Or the line connection device according to 2, further comprising a secret device connected between the private branch exchange and the line network when the type of the device to be exchanged is a telephone, and wherein the control unit controls the secret device in accordance with the type of the device to be exchanged. Connection and disconnection.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a line connection device according to the present invention will be described below with reference to the accompanying drawings. The components having the same functions as those of the components of the conventional communication system S1 are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 1, this communication system S
Is a control station BS and slave stations CS1 distributed in N places.
To CSn (hereinafter referred to as “slave station CS” when not distinguished), for example, via a radio network (corresponding to a network in the present invention) using radio frequencies of frequencies f1 to fn. The control station BS and the N slave stations CS are configured to be able to communicate with each other. In this case, the control station BS includes the line connection device 1 and the n telephones T1 to Tn.
And a general-purpose private branch exchange 2 for performing exchange processing for exchanging and connecting the exchange target equipment including m fax machines F1 to Fm and the n-wire 4-wire lines 4WS and 4WR, and a duplex using, for example, VHF. Type F
And M radios, each having a different transmission / reception frequency.
In this case, the line connection device 1 includes a maximum n-line 4-wire line 4WS, 4WR connected to the private branch exchange 2, and a maximum n-line 4-wire line 4WS connected to the n wireless devices 3, 3,. , 4WR, and various processes to be described later can be executed. In addition,
Regarding the connection processing by the line connection device 1,
Since a general known technique is used, the description thereof is omitted.

On the other hand, each slave station CS, which is connected to the control station BS via a wireless line, includes a line connection device 1, a private branch exchange 2, and a wireless device 3, and has one of the frequencies f1 to fn. The radio frequency of the waves is used to enable mutual communication with the control station BS. In this case, slave station C
The line connection device 1 in S is configured so that any one of the telephones T1 to Tn and the facsimile devices F1 to Fm and one radio 3 can be connected to each other via the four-wire lines 4WS and 4WR. The control station BS has almost the same function as the line connection device 1 in the control station BS, except for the number of connectable lines. Therefore, in this specification, the line connection devices 1 of the control station BS and the slave station CS will be described as having the same reference numerals and having the same functions. Similarly, the private branch exchange 2 in each slave station CS has the same function as the private branch exchange 2 in the control station BS.

FIG. 2 is a block diagram of the control station BS in which a part of the configuration of the control station BS in FIG. 1 is omitted.
As shown in FIG. 1, the line connection device 1 includes a control unit 11 and D
It comprises a TMF encoder / decoder 12, a secret device 13 used for telephone communication, a changeover switch 14, an analog switch 15 corresponding to a switch means in the present invention, and an MSK modem 16. In addition to the above-described connection processing, the line connection apparatus 1 transmits and receives MSK signals such as a dial signal, an advance notification signal and an end signal, a line connection / interruption processing, and a secret communication apparatus 1.
3 is connected and released.

In this communication system S, for example, when a predetermined FAX apparatus F in the control station BS calls a predetermined FAX apparatus F in the slave station CS, first, the private branch exchange 2
Outputs the SS signal to the control unit 11 of the line connection device 1. Next, the private branch exchange 2 outputs the DTMF signal output from the FAX device F to the DTMF encoder / decoder 12 in the line connection device 1. Next, the DTMF encoder / decoder 12 converts the DTMF signal into binary digital number data and outputs it to the control unit 11. On the other hand, the control unit 11 activates the transmission unit in the wireless device 3 by outputting the transmission control signal PTT to the wireless device 3, and transfers the digital number data to the MSK modem 16, thereby transmitting the number data by the MSK signal. Is generated and output to the 4-wire line 4WS. Thereby, the wireless device 3 transmits the wireless signal modulated by the MSK signal to the frequency f1.
To send. Next, the control unit 11 controls the analog switch 15 to the on state by outputting the control signal SC2. As a result, the fax machine F on the calling side and the wireless device 3 are connected to each other by the 4-wire lines 4WS and 4WR.

On the other hand, in the slave station CS on the receiving side, the radio 3
Receives the radio signal, demodulates it into an MSK signal,
K signal to the line connection device 1 and the incoming signal S
Q is output to the control unit 11 in the line connection device 1. Next, the MSK modem 16 in the line connection device 1 converts the number data as the MSK signal into binary digital number data and outputs the same to the control unit 11. Subsequently, the control unit 11
Converts the digital number data into a DTMF encoder
The analog switch 15 is turned on by transmitting the control signal SC2 to the decoder 12 and outputting the control signal SC2. Thereafter, the SS signal is output to the private branch exchange 2. Next, the DTMF encoder / decoder 12 outputs a DTMF signal obtained by encoding the digital number data to the private branch exchange 2. Next, the private branch exchange 2 calls the FAX device F corresponding to the dial number based on the DTMF signal, and when the FAX device F answers, the control unit 11
To output an SS signal as a call enable signal. As a result, in this state, the FAX device F on the slave station CS side is connected to the wireless device 3 via the four-wire lines 4WS and 4WR, so that the FAX device F on the transmitting side and the FAX device F on the receiving side are wirelessly connected. They are interconnected via a network. Control unit 1
1 outputs digital data as a call enable signal to the MSK modem 16 and encodes it into an MSK signal. As a result, the call enable signal is transmitted by the wireless device 3.
Subsequently, the control unit 11 determines whether or not the transfer signal has been transmitted by the control station BS from the time when the SS signal as the call enable signal is input until a predetermined time has elapsed. Monitor based on In this case, the transfer signal is a signal used in the process of establishing a connection between the FAX devices F and F, and is a signal that can identify that the type of the device to be exchanged is a FAX device, and is a DIS signal or an NSF signal. And so on.

In this case, the control unit 11 on the control station BS side
During a period from when the call enable signal transmitted by the slave station CS is input via the wireless device 3 and the MSK modem 16 to when a predetermined time has elapsed, the handover signal in the process of establishing the connection by the FAX apparatus F is the slave station. It monitors whether or not it has been transmitted by the CS based on the demodulated signal of the MSK modem 16. Next, when communication between the facsimile apparatuses F, F is started, the facsimile apparatus F on the control station BS side transmits a handover signal for connection to the facsimile apparatus such as a ringing tone, so that the handover signal is transmitted wirelessly. It is output to the device 3 and transmitted to the slave station CS side.

On the other hand, on the slave station CS side, the control unit 11
The demodulation signal of the SK modem 16 is monitored at predetermined intervals, and when the connection transfer signal transmitted from the control station BS is detected, for example, twice consecutively, the type of the exchange target device is determined to be the FAX device F. If the transfer signal is not detected twice consecutively, the type of the exchange target device is determined to be the telephone T. As a result, as compared with the method of immediately determining the type of the device to be exchanged at the time of detecting the transfer signal once, erroneous determination due to the contamination of noise and a signal approximate to the frequency component of the transfer signal for connection are reduced. As a result, it is possible to prevent erroneous determination when the signal is included in the demodulated signal of the MSK modem 16, thereby improving the reliability of the determination. in this case,
The transfer signal is transmitted by the MSK modem 16 to, for example, 18.
It is detected as a 00 Hz signal. Thereafter, the facsimile apparatus F sends out a CED signal as a called station identification signal and a DIS signal and an NSF signal following this signal, and the transfer signal for these connections is a 4-wire line 4WS, 4W
After being output to the wireless device 3 via R, it is transmitted to the control station BS via a wireless line. When the control unit 11 determines that the type of the exchange target device is the telephone T, the control unit 11 outputs the control signal SC1 and controls the changeover switch 14 to control the secret device 1 between the four-wire lines 4WS and 4WR.
3 is connected. As a result, secrecy during telephone communication can be maintained, and communication quality can be improved.

On the other hand, in the same manner, the control unit 11 of the control station BS also detects the exchange signal input via the radio 3 and the MSK modem 16, for example, twice consecutively, at the time when the exchange target device is detected. Is determined to be a fax machine.
In this case, the transfer signal as the called station identification signal is also detected by the MSK modem 16 as a signal of, for example, 1800 Hz. In this control station BS, when the control unit 11 determines that the type of the exchange target device is the telephone set T, the control unit 11 outputs the control signal SC1 and outputs the control signal SC1.
4 by switching control, the 4-wire circuit 4WS, 4
The secret talker 13 is connected between the WRs.

Thereafter, when the call ends, for example, the control station BS
The FAX device F on the side transmits a message end signal to the FAX device F on the slave station CS, so that both the control station BS and the FAX devices F on the slave station CS go on-hook. Next, both the private branch exchanges 2 and 2 on the transmitting side and the receiving side stop the output of the SS signal to each control unit 11 after recognizing the end call by the on-hook of the facsimile apparatus F. As a result, both control units 11 output the control signal SC2 to switch the analog switch 15 to the off state, thereby disconnecting the lines.

On the other hand, in the case of communication between the telephones T, for example, when the telephone T on the control station BS goes on-hook, the private branch exchange 2 on the control station BS stops outputting the SS signal to the control unit 11. . Next, the control section 11 outputs a control signal SC2 to control the analog switch 15 to be turned off, thereby cutting off the line. Subsequently, the control unit 11 sequentially outputs the digital data cutoff notice signal and the end signal to the MSK modem 16 to notify the MSK modem 16 of the cutoff notice of the MSK signal consisting of a continuous tone of 1800 Hz. Signal, and 1
An end signal of an MSK signal composed of a combination of a 200 Hz tone and a 1800 Hz tone is transmitted to a 4-wire line 4 W
Let S send out. As a result, the pre-cutoff notification signal and the end signal are sequentially transmitted by the wireless device 3.

At this time, on the side of the slave station CS, the MSK modem 16 sequentially inputs the cut-off pre-notification signal and the end signal by the MSK signal via the radio 3, and the digital data cut-off pre-notification signal and the end call. The signals are converted into signals and sequentially output to the control unit 11. In this case, the control unit 11
When the pre-shutdown notification signal is input, the control signal SC2 is output to switch the analog switch 15 to the off state to cut off the line. Next, when the end signal is input, the control unit 11 maintains the analog switch 15 in the off state and stops outputting the SS signal to the private branch exchange 2. As a result, the private branch exchange 2 outputs an end signal to the telephone set T of its own office. As a result, the talker on the slave station CS side can reliably determine the end without listening to the harsh end signal, and the slave station CS can also reliably cut off the line.

Thus, in this communication system S1,
The control unit 11 controls the FAX device F via the MSK modem 16
The type of the device to be exchanged is determined to be the FAX device F based on the facsimile device identifiable signal output from the FAX, and the correspondence between the type of the device to be exchanged and the line number is stored in the private branch exchange 2. Since there is no need to perform this, a general-purpose private branch exchange 2 can be used. As a result, an inexpensive private branch exchange 2 can be used, and the control station B
The cost of the communication system S and the slave station CS can be reduced, and the cost of the communication system S can be reduced.

The present invention is not limited to the above embodiment. For example, in the embodiment of the present invention, an example has been described in which a DIS signal or an NSF signal is used as a facsimile apparatus identifiable signal. However, the facsimile apparatus identifiable signal in the present invention is not limited to this, and may be a GI code (group). Various signals that can be distinguished from the facsimile machine, such as an identification code, can be used. However, the type can be quickly determined by performing the determination based on the DIS signal or the NSF signal used at the head of the message. Further, the network in the present invention is not limited to a wireless network, but may be a private wired network. Further, the MSK modem according to the present invention can be constituted not only by a general-purpose MSK modem but also by a tone decoder capable of detecting a facsimile apparatus identifiable signal or a band-pass filter. Further, in the embodiment of the present invention, each unit of the line connection device 1 is shown in a functional block diagram, but these configurations are not limited to a hardware configuration, but may be a DSP (Digital Sign).
al Processor) can be realized by software.

[0028]

As described above, according to the line connection apparatus of the first aspect, the control unit can determine the type of the equipment to be exchanged in accordance with the detection of the facsimile apparatus identifiable signal. An exchange can be used, and thereby the cost of the communication system including the line connection device and the private branch exchange can be reduced. In addition, when the facsimile apparatus identifiable signal is detected at least twice consecutively, the type of the exchange processing target apparatus is determined as the facsimile apparatus, thereby improving the reliability of the type determination.

According to the second aspect of the present invention, the type of the device to be exchanged can be changed by using the transfer signal in the process of establishing the connection by the facsimile device as the facsimile device identifiable signal. At the time of connection,
Thus, various processes according to the type of the exchange processing target can be started quickly.

Further, according to the line connection device of the third aspect, the control unit connects and disconnects the secret device according to the type of the device to be exchanged, so that the control unit performs the connection according to the type of the device to be exchanged. The line quality can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a communication system S according to an embodiment of the present invention.

FIG. 2 is a block diagram in which a part of a control station BS according to the embodiment of the present invention is omitted.

FIG. 3 is a block diagram of a communication station TS in a conventional communication system S1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Line connection device 2 Private branch exchange 11 Control part 12 DTMF encoder / decoder 13 Secret device 15 Analog switch 16 MSK modem F1-Fm FAX device S Communication system T1-Tn Telephone

Claims (3)

[Claims] 1. A switch unit for connecting and disconnecting a line between a private branch exchange that performs exchange processing on a device to be exchanged including a telephone set and a facsimile machine and a line network, and an MSK signal transmitted from the line network. MSK for demodulating and generating an MSK signal to be transmitted to the line network
And when the type of the exchange target device is the telephone, causes the MSK modem to send a line disconnection advance notification signal to the line network prior to the end signal, and transmits the MSK modem from the line network. A line connection device comprising: a control unit that causes the switch unit to perform the line disconnection when a line disconnection advance notification signal is detected based on the demodulated signal of the MSK modem. When the facsimile device identifiable signal included in the demodulated signal of the modem is continuously detected at least twice, the type of the exchange target device is determined as the facsimile device, and the facsimile device identifiable signal is continuously output. When the detection is not detected, the type of the exchange target device is determined as the telephone, and the line disconnection advance notification signal is detected. A line connection device for causing said switch means to perform said line disconnection. 2. The facsimile machine identifiable signal,
2. The line connection apparatus according to claim 1, wherein the signal is a transfer signal in a process of establishing a connection by the facsimile apparatus. 3. A secret device connected between the private branch exchange and the line network when the type of the device to be exchanged is the telephone, and the control unit controls the type of the device to be exchanged according to the type of the device to be exchanged. 3. The line connection device according to claim 1, wherein connection and disconnection of the secret device are performed.