KR100306748B1 - Apparatus for transmitting and receiving telephone/facsimile signal in the facsimile system - Google Patents

Abstract

According to the present invention, in a facsimile system having a telephone, when the telephone and the facsimile are used through two data communication channels and two codecs, the analog signals required for the telephone and the facsimile are different. You need to adjust the gain levels for the analog and fax signals separately, inserting a gain adjustment circuit for the characteristics of the analog voice signal required by the telephone handset and the analog modem signal required by the fax modem. Accordingly, the present invention relates to a telephone / fax transceiver of a facsimile system that switches signals through a plurality of multiplexers according to a purpose.

According to the present invention, there is an advantage of providing a telephone function and a manual transmission / reception function of a fax document at the same time by using a facsimile system on a comprehensive information communication network. As the fax modem is connected to the data communication channel and the voice call path is blocked, it is possible to provide a reliable fax transmission and reception function.

Description

Apparatus for transmitting and receiving telephone / facsimile signal in the facsimile system

The present invention relates to a telephone / fax transceiver of a facsimile system, and more particularly, by inserting a gain adjusting circuit suitable for the characteristics of the analog voice signal required by the telephone handset and the analog modem signal required by the fax modem. The present invention relates to a telephone / fax transceiver of a facsimile system capable of simultaneously providing a telephone function and a manual transmission / reception function of a fax document by switching a signal through a plurality of multiplexers according to an input signal.

Integrated Services Digital Network (ISDN) is a digital network that comprehensively supports voice and non-voice services. Public Switched Telephone Network (PSTN), Public Switched Data Network (PSDN), Telex, and Fax Dedicated Networks It refers to a digital communication network that converts all the different types of information such as voice and text data such as text and video data into digital ones and transmits them in one network at a time. G3 facsimile (or G3 facsimile) It refers to the Group 3 facsimile. The G3 facsimile is the most commonly used facsimile, which is used in analog networks.

While analog method, which is a general telephone method, provides only one channel, digital ISDN, which is a digital method, provides two channels as the basic rate interface (BRI) has a 2B + 1D channel structure as a basic structure. You can also use computer communication and fax at the same time you use the phone. In other words, when using different types of services, all operations can be performed in one integrated network (ISDN) without installing a separate line for each.

In addition, the ISDN has the advantage of high speed because there is no noise and less sound loss because the digital signal is exchanged as it is.

The characteristics of this Integrated Information Network (ISDN) are as follows in terms of subscribers and network providers.

First, in the existing network, the user had to separately manage the subscription fee and the service use number for each service, but in the integrated information communication network (ISDN), all things can be unified, so management is simplified. In addition, in spite of various communication functions and breakthrough communication capabilities, it is economically advantageous because the usage fee is relatively low.

Second, from the provider side, the previous analog telephone network was difficult to expand network functions, costly to construct a network, and difficult to provide a complex service, but it is easy to introduce a new service in an integrated information communication network (ISDN), Complex services can be provided at the same time, and network configuration and application can be economically performed.

The ISDN terminal using this ISDN as a transmission path must transmit the communication characteristics of the transmitting terminal to the receiving terminal in order to talk to the receiving terminal. This is because ISDN provides several kinds of services in one communication network, and the communication path can be established only when the communication capability of the transmitting side and the receiving side is the same.

That is, when a transmitting terminal is an ISDN dedicated telephone and a plurality of terminals such as an ISDN telephone, a personal computer (PC), and a G4 facsimile are connected to the receiving terminal, the terminals other than the telephone do not respond to the calling signal and only the telephone signal is called. This is to create a currency path in response. The exchange of communication capabilities between the transmission and reception is performed through the D channel, and uses a layer 3 protocol among ISDN protocols. Data transmission and reception for communication capability exchange is as follows.

ISDN terminals are classified into various bearer services such as 64kbps voice, 64kbps 3.1 kHz audio, and 64kbps unrestricted information according to the type of information to be transmitted. 64 kbps voice is for transmitting voice information, such as ISDN telephone, and 3.1 kHz audio is for information transmission devices using voice band signals, that is, for transmitting a terminal equipped with a fax modem. And the 64kbps unrestricted information is for information transmission of pure digital data such as generated on a PC. The reason for distinguishing several types of bearer services as described above is that each ISDN needs to have a different information transmission path according to the type of transmission information.

That is, the voice information is echo canceller, A / It is transmitted along a path with a conversion device and a Digital Circuit Multiplication Equipment (DMEME), and the non-limiting information must go through a pure digital path, not this path.

Therefore, if the transmitting terminal includes an appropriate communication capability in the information element of the SET-UP message, which is a layer 3 message required for call setup, according to what information the transmitting terminal transmits, and the receiving terminal is an ISDN telephone, When the setup message is transmitted by including the content of '64 kbps voice 'in the information element, the receiving terminals receive the setup message through the exchange, and the ISDN telephone corresponding to the '64 kbps voice' information responds to an ALERTING message. By sending to the exchange side, it informs that it can talk to the transmitting terminal. As described above, in ISDN, the call paths can be formed only when the transmitting and receiving terminals have the same communication capability.

Existing ISDN MFPs, when talking via a telephone handset and attempting a fax communication, maintain some of the functions of additional devices such as echo cancellers and DCME (Digital Circuit Multiplication Equipment) installed in the exchange. The possibility of a communication error increases. In other words, DCME uses ADPCM (Adaptive Differential Pulse Code Modulation) to reduce the speed to 32 kbps transmission rate for multiplexing multiple channels. When the facsimile communication signal is converted in this way, the receiving side There is a problem that is more likely to be misunderstood.

In addition, since the analog transmission levels of voice signals and fax modem signals are different, the transmission and reception levels of telephone handset and fax modem signals must be adjusted separately. When the level is set to the voice signal, the signal input to the fax modem is too large to be recognized by the fax modem. When the level is set to the fax modem, the voice signal to the telephone handset is too small.

Accordingly, the present invention has been devised to solve such a problem, and in the above-described Integrated Information Communication Network (ISDN), the present invention provides a facsimile system having a telephone in which two data communications of the Integrated Information Communication Network (ISDN) are performed. Manual transmission and reception of fax and fax documents using a facsimile system over a telecommunications network to enable both telephone and facsimile using a channel (ie 2B channel) and two codecs (Coder / Decoder). An object of the present invention is to provide a telephone / fax transceiver of a facsimile system capable of simultaneously providing a system.

1 is a block diagram showing a preferred embodiment of a telephone / facsimile public interface device of an analog fax system according to the present invention;

2 is a circuit diagram showing the switching circuit unit according to the present invention;

3 is a circuit diagram illustrating an inverting amplifier for explaining a first codec and a second codec of the present invention;

4 is a circuit diagram illustrating a hook on / off circuit of a typical facsimile system.

<Explanation of symbols for the main parts of the drawings>

10: fax modem 20: telephone handset

100: switching circuit unit 200: switching control unit

210: first multiplexer 220: second multiplexer

230: third multiplexer 240: fourth multiplexer

300: first codec 310: second codec

400: ISDN connection control unit R1: first resistor

R2: second resistor R3: third resistor

R4: fourth resistor R5: fifth resistor

R6: sixth resistor R7: seventh resistor

R8: eighth resistor R9: ninth resistor

In order to achieve the above object, the telephone / fax transceiver of the facsimile system according to the present invention, in the facsimile system having a telephone, when using both the telephone and the fax through two data communication channels and two codecs, Because the magnitude of the analog signal required for the telephone and facsimile is different, the gain levels for the analog signal of the telephone and the analog signal of the facsimile must be adjusted separately.The analog voice signal required by the telephone handset and the analog modem required by the fax modem Telephone / facsimile switching and interface functions to allow manual transmission and reception of fax documents in ISDN fax systems by inserting gain adjustment circuits for each signal, and then switching the signals through multiplexers according to the external input signal. To provide It is characteristic.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the telephone / fax transmission and reception apparatus of the facsimile system according to the present invention.

1 is a block diagram showing a preferred embodiment of the telephone / fax transmission and reception apparatus of the fax system according to the present invention.

As can be seen from Figure 1, a preferred embodiment of the present invention provides a telephone function through a telephone handset 20 in two data communication channels of an integrated information network (ISDN) while simultaneously providing a fax document through a fax modem (10). In a facsimile system for providing a passive transmission and reception function,

As the magnitude of the analog modem signal required by the fax modem 10 and the magnitude of the analog voice signal required by the telephone handset 20 are adjusted, the gain level is adjusted through a gain adjustment circuit for each characteristic. And a switching circuit unit 100 for switching a plurality of multiplexers in accordance with a mux control signal to distinguish a transmission / reception signal path of the fax modem 10 and a transmission / reception signal path of the telephone handset 20;

As the operation mode of the facsimile system is selected as one of the telephone mode and the fax mode by an external input signal, a MUX control signal is applied to the switching circuit to enable any one of the two data communication channels. Controlling the multiplexers to be connected to a data communication channel; and, when switching to the fax mode during a voice call in the phone mode, the plurality of multiplexers are disconnected while the fax modem is connected to the currently connected data communication channel. A switching controller 200 for controlling the multiplexer;

Analog-to-digital conversion or the first data to a digital modem signal or a digital voice signal for transmitting the gain-adjusted analog modem signal or the analog voice signal through a first data communication channel of the Integrated Services Digital Network (ISDN), respectively. A first codec (300) for digitally / analog converting the digital modem signal or the digital voice signal received in a communication channel into the analog modem signal or the analog voice signal; And

Analog-to-digital conversion or the second data into a digital modem signal or a digital voice signal for transmitting the gain-adjusted analog modem signal or the analog voice signal through a second data communication channel of the Integrated Services Digital Network (ISDN), respectively. A second codec (310) for digitally / analog converting the digital modem signal or the digital voice signal received in the communication channel into the analog modem signal or the analog voice signal; And

ISDN access control unit 400 which is connected to the first codec 300 and the second codec 310 and receives the dialing information provided from the facsimile system and meets the necessary standards when connecting to the integrated information communication network (ISDN). It is composed of

With reference to the accompanying drawings, a preferred embodiment of the telephone / facsimile public interface device of the analog facsimile system according to the present invention configured as described above will be described in detail.

First, the switching control unit 200 applies a MUX control signal to the switching circuit unit as the operation mode of the facsimile system is selected as one of a telephone mode and a fax mode by an external input signal. Controlling the multiplexers so as to be connected to any one of the available data communication channels, while the fax modem is connected to the currently connected data communication channel when switching from the telephone mode to the fax mode during a voice call. The multiplexer is controlled to block a voice call path.

When a mux control signal is required, the switching control unit 200 latches a necessary signal by sending a signal necessary for mux control to a data bus together with a mux enable signal from a facsimile system that is a main system. Control the multiplexer.

Accordingly, the switching circuit unit 100 has a gain adjusting circuit for each characteristic as the magnitude of the analog modem signal required by the fax modem 10 and the magnitude of the analog voice signal required by the telephone handset 20 are different. The multiplexers are switched according to a mux control signal to adjust the gain level through the control unit and distinguish the transmit / receive signal path of the fax modem 10 from the transmit / receive signal path of the telephone handset 20.

2 is a circuit diagram illustrating the switching circuit unit 200 according to the present invention.

As shown in FIG. 2, the switching circuit unit 100 is serially connected to a transmitting unit of the fax modem 10 to determine a gain level for the analog modem signal when the analog modem signal is transmitted. A first resistor R1, a first capacitor C1 and a second resistor R2 which simultaneously provide a current path;

The analog modem has the same resistance value as the internal resistance measured by the first receiving output terminal RxO of the first codec 300 and is connected to the receiving unit of the fax modem 10 to receive the analog modem signal. A third resistor (R3) for determining a gain level for the signal and at the same time providing a current path;

Has a resistance value smaller than the eighth resistor R8, and is serially connected to the talker 21 of the telephone handset 20 to determine a gain level for the analog voice signal when the analog voice signal is transmitted. A second capacitor C2 and a fourth resistor R4 that provide a current path at the same time;

It has a resistance value relatively smaller than the internal resistance value measured at the first receiving output terminal RxO of the second codec 310, and is connected to the receiver 22 of the telephone handset 20 to receive the analog voice signal. A fifth resistor (R5) which, when present, determines a gain level for the analog voice signal and provides a current path;

A first switching contact is connected to the second resistor R2, a second switching contact is connected to the fourth resistor R4, and a main switching terminal is connected to the first transmission input terminal (−) of the first codec 300. A first multiplexer 210 connected to Tx);

A first switching contact is connected to the common contact of the fourth resistor R4 and the second switching contact of the first multiplexer 210, and a second switching contact is connected to the second resistor R2 and the first multiplexer ( A second multiplexer (220) connected to a common contact of a first switching contact of 210, and a main switching terminal of which is connected to a first transmission input terminal (-Tx) of the second codec (310);

A first switching contact is connected to the third resistor R3, a second switching contact is connected to the fifth resistor, and a main switching terminal is connected to the first receiving main switching terminal RxO of the first codec 300. A third multiplexer 230 connected to the;

A first switching contact is connected to the common contact of the fifth resistor R5 and the second switching contact of the third multiplexer 230, and the second switching contact is connected to the third resistor R3 and the third multiplexer ( A fourth multiplexer (240) connected to the common contact of the first switching contact of 230, and the main switching terminal of which is connected to the first receiving output terminal (RxO) of the second codec (310);

Has the same resistance value as the second resistor (R2), one side is connected to the common contact between the main switching terminal of the first multiplexer 210 and the first transmission input terminal (-Tx) of the first codec 300 The analog modem signal or the analog voice signal, the other side of which is connected to the second transmission input terminal TxI of the first codec 300 and is input to the first switching contact or the second switching contact of the first multiplexer 210. A sixth resistor (R6) operating with a parameter for determining a gain level of the transistor;

One side is connected to the common contact of the sixth resistor R6 and the second transmission input terminal TxI of the first codec 300, and the other side is a main switching terminal of the third multiplexer 230 and the first codec. A seventh resistor R7 connected to the common contact of the receive output terminal RxO of 300;

Has the same resistance value as the sixth resistor (R6), one side is connected to the common contact of the main switching terminal of the second multiplexer 220 and the first transmitting input terminal (-Tx) of the second codec 310 The other side is connected to the second transmission input terminal TxI of the second codec 310 and the analog modem signal or the analog voice signal input to the first switching contact or the second switching contact of the second multiplexer 220. An eighth resistor R8 operating with a parameter for determining a gain level of the transistor;

One side is connected to the common contact of the eighth resistor R8 and the second transmission input terminal TxI of the second codec 310, and the other side is a main switching terminal of the fourth multiplexer 240 and the second codec. And a ninth resistor R9 connected to the common contact of the receive output terminal RxO of 310.

The main switching terminals of the multiplexers 210, 220, 230, and 240 are simultaneously switched to the first switching contact or the second switching contact according to the mux control signal to the switching controller 200.

By default, the first switching contacts of each of the multiplexers 210,220, 230,240 are preferably all connected to the respective main switching terminals.

On the other hand, the first resistor (R1), the second resistor (R2), the sixth resistor (R6) in the fax mode, the gain level so that the magnitude of the analog voice signal, which is the analog modem signal required by the fax modem 10 is satisfied. The third resistor R3, the fourth resistor R4, and the fifth resistor R5 are gain levels such that the magnitude of the analog modem signal, which is the analog voice signal required by the telephone handset 20 in the telephone mode, is satisfied. Adjust it.

The first codec 300 is analog / digital as a digital modem signal or a digital voice signal for transmitting the gain-adjusted analog modem signal or the analog voice signal through a first data communication channel of the Integrated Services Digital Network (ISDN), respectively. Converting or digitally / analogly converting the digital modem signal or the digital voice signal received in the first data communication channel into the analog modem signal or the analog voice signal, and a second codec 310 converts the gain-adjusted analog Analog / digital conversion to a digital modem signal or a digital voice signal, or received on the second data communication channel, respectively, for transmission of a modem signal or the analog voice signal through a second data communication channel of the Integrated Services Digital Network (ISDN). The digital modem signal or the digital A voice signal to the analog modem signals or the analog audio signal and converts the digital / analog.

The ISDN access control unit 400 is connected to the first codec 300 and the second codec 310 to receive dialing information provided by the facsimile system, and is required when connecting to the integrated information communication network (ISDN). Satisfies

3 is a circuit diagram illustrating an inverting amplifier for explaining the first codec 300 and the second codec 310 of the present invention.

The analog modem signal input from the transmitter of the fax modem 10 is controlled by a first resistor R1, a second resistor R2, a sixth resistor, and a first capacitor C1, and the first multiplexer. The first transmission input terminal (-Tx) of the first codec 300 connected to the main switching terminal of 210 is an inverting input terminal (-) of the inverting amplifier as shown in FIG. 3, and in the case of the first codec 300, The gain level of the input signal is determined by the second resistor R2 and the sixth resistor R6, and in the case of the second codec 310, the input signal is determined by the fourth resistor R4 and the eighth resistor R8. The gain level of is determined.

In other words, the output voltage of the inverting amplifier ( ) And gain ( ) Is determined as in Equation 1, wherein the second resistor R2 and the sixth resistor R6 are resistors, respectively. With resistance In the same manner, the fourth resistor R4 and the eighth resistor R8 are also resistors. With resistance Corresponds to.

,

The first transmission input terminal (-Tx) of the first codec 300 and the second codec 310 corresponds to the inverting input terminal (-) of the inverting amplifier shown in FIG. 3, and the first codec 300 and the second The second transmit input (TxI) of the codec 310 is a resistor Output voltage connected to ).

As described above, the output voltage of this inverting amplifier ( ) Is as in Equation 1 Of You can adjust the level according to the value. In other words, With fixed value Larger increases the gain, With fixed value If you increase, the gain decreases, Smaller increases the gain.

Therefore, the two codecs, namely, the first codec 300 and the second codec 310, are not fixed for the analog modem signal transmission or reception for the analog voice signal transmission or the modem (i.e., for the fax) or telephone depending on the situation. In order to use for the purpose (that is, voice), the sixth resistor R6 and the eighth resistor R8 are fixed, and the second resistor R2 and the fourth resistor R4 are adjusted to suit each application. Gain level can be set.

That is, since the gain of the input analog modem signal should not exceed 0 dBm, the second resistor R2 connected to the transmitter of the fax modem 10 sets the second resistor R2 and the sixth resistor R6 to the same value. (I.e., gain = 1), the fourth resistor R4 connected to the transmitter 21 of the telephone handset 20 has a small level of the input analog voice signal so that the gain is 1 or more (gain> 1). The resistance value of the fourth resistor R4 is adjusted to a smaller resistance value than the eighth resistor R8 so as to be configured.

When the signal is received, the level of the received signal is adjusted by the third resistor R3 and the fifth resistor R5. A resistor having a function is mounted inside the first codec 300 and the second codec 310.

Therefore, since the third resistor R3 is a portion connected to the fax modem 10, the third resistor R3 is adjusted to the same resistance value as the internal resistance measured by the first receiving output terminal RxO of the first codec 300, and the fifth resistor R5 is the fifth resistor. Since R5 is a portion that is connected to the telephone handset 20, it is set to a relative resistance value smaller than the internal resistance value measured at the first receiving output terminal RxO of the second codec 310.

The level adjustment circuit set according to the use enables the facsimile manual transmission and reception. For clarity, the following description will be given as an example.

The analog voice signal input through the telephone handset 20 is input to the second codec 310 through the fourth resistor R4 and the second multiplexer 220, which is leveled for the voice signal, and transmits the analog voice signal. When receiving a signal, an analog voice signal is received through the fifth resistor R5 and the fourth multiplexer 240 so that a call is made according to a circuit adapted to the voice level. When switched, the sending terminal is pressed the start button to send the fax original. Then, at the same time as pressing the start button, the first multiplexer 210 and the third multiplexer 230 are switched to the second switching contact, respectively, under the control of the switching controller 200, so that the analog voice signal is connected to the second codec 310. The second multiplexer 220 and the fourth multiplexer 240 are also switched to the second switching contact so that the analog modem signal is connected to the second resistor R2 and the second multiplexer. The signal is input to the second codec 310 through the 220 and converted into a digital signal, and then transmitted through the transmission output terminal TxD of the second codec 310. When the digital modem signal input through the receiving input terminal RxD of the second codec 310 is digital / analog converted by the second codec 310 and then output through the receiving output terminal RxO of the second codec 310, The first and second resistors R3 are connected to the third resistor R3 according to the reception level of the analog modem signal received through the second switching contact of the fourth multiplexer 240 and received by the fax modem 10.

Circuitry for the telephone handset 20 connected to the first codec 300 can make a call even during facsimile communication, provided the remaining data transfer channels are available.

The first codec 300 and the second codec 310 are fixed to the first data communication channel (B1 channel) and the second data communication channel (B2 channel), respectively, and the first data communication channel (B1 channel) and the first codec 300 are fixed. Digital data transmission / reception control of the two data communication channels (B2 channels) is performed by the STB1 signal and the STB2 signal. That is, the STB1 signal input to the first codec 300 is fixed to the B1 channel and the STB2 signal is fixed to the B2 channel.

In order to help the understanding of the present invention, a case of using a facsimile after a phone call will be described with reference to an operation process of the present invention.

By default, it is assumed that the main switching terminals of each of the multiplexers 210, 220, 230, 240 and 250 are all connected to the respective first switching contacts.

By hooking off the telephone handset 10 mounted in the facsimile system, the facsimile system detects the hook-off state through the hook on / off circuit unit as shown in FIG. 4. When dialing in the hook-off state, the ISDN protocol SET-UP LAYER 3 MESSAGE is transmitted to the exchange side for call connection. At this time, the information element in the setup message is set to '64kbps 3.1kHz audio'.

The exchange receiving the setup message transmits an ALERTING message to the sender if the receiver is available to make a call so that the sender can receive the message and confirm the ready state of the receiver.

The switching control unit 200 of the transmitting terminal receiving the alerting message determines which data communication channel is available, and if the second data communication channel (B2 channel) is available, the main switching terminals of the multiplexers 210, 220, 230, 240, and 250 are used. If they both remain connected to each of the first switching contacts, the process proceeds to the next process, while if it is determined that the usable channel is the first data communication channel (B1 channel), each multiplexer of FIG. The main switching terminals of (210, 220, 230, 240, 250) are all switched to their respective second switching contacts.

If you press the FAX SEND button on the terminal to send a fax document during voice call, the main switching terminals of each of the multiplexers 210, 220, 230, 240, and 250 are all switched from the currently connected switching contact to another switching contact. It cuts the communication line and connects with the circuit of the fax modem 10 side. When the transmission of the fax document is completed, the main switching terminals of each of the multiplexers 210, 220, 230, 240, and 250 are all switched to their respective first switching contacts to return to their original states.

Terminologies used herein are terms defined in consideration of functions in the present invention, which may vary according to the intention or customs of those skilled in the art, and the definitions should be made based on the contents throughout the present application. will be. Although specific embodiments of the invention have been described and illustrated, it will be apparent that the invention may be embodied in various modifications by those skilled in the art.

In addition, since the present invention has been described through the preferred embodiment of the present invention, in view of the technical difficulty aspects of the present invention, those having ordinary skill in the art can easily be different from another embodiment of the present invention. As modifications may be made, it is obvious that both the embodiments and modifications cited in the above description belong to the appended claims.

As described in detail above, a gain adjusting circuit suitable for the characteristics of the analog voice signal required by the telephone handset and the analog modem signal required by the fax modem is inserted, and then the signal is transmitted through a plurality of multiplexers according to an external input signal. According to the present invention, which can simultaneously provide a telephone function and a manual transmission / reception function of a fax document by switching to a purpose, an advantage of simultaneously providing a telephone function and a manual transmission / reception function of a fax document using a facsimile system on a comprehensive information communication network. In this case, when the phone mode is switched to the fax mode during the voice call, the fax modem is connected to the currently connected data communication channel, thereby blocking the voice call path, thereby providing a reliable fax transmission / reception function.

Claims (7)

A facsimile system for providing a telephone function through a telephone handset on two data communication channels of a digital communication network and at the same time providing a manual transmission and reception of a fax document through a fax modem. As the magnitude of the analog modem signal required by the fax modem and the magnitude of the analog voice signal required by the telephone handset are different, each gain level is adjusted through a gain adjustment circuit for each characteristic. A switching circuit unit for switching a plurality of multiplexers according to a MUX control signal to distinguish between a transmit / receive signal path and a transmit / receive signal path of the telephone handset; Analog-to-digital conversion or reception on the first modem data channel or a digital modem signal or digital voice signal for transmitting the gain-adjusted analog modem signal or the analog voice signal through a first data communication channel of the digital communication network, respectively. A first codec for digitally / analog converting the digital modem signal or the digital voice signal into the analog modem signal or the analog voice signal; And Analog-to-digital conversion or reception on the digital modem signal or digital voice signal, respectively, for transmitting the gain-adjusted analog modem signal or the analog voice signal over a second data communication channel of the digital communication network. A second codec for digitally / analog converting the digital modem signal or the digital voice signal into the analog modem signal or the analog voice signal; And And a digital communication network access control unit which is connected to the first codec and the second codec and receives dialing information provided from the facsimile system and satisfies a standard required for accessing the digital communication network. / Fax transceiver. The method of claim 1, As the operation mode of the facsimile system is selected as one of the telephone mode and the fax mode by an external input signal, a mux control signal is applied to the switching circuit to connect to any one of the two data communication channels available. And a switching controller for controlling the plurality of multiplexers so that the telephone / fax transceiver of the facsimile system. The method of claim 1, As the operation mode of the facsimile system is selected as one of the telephone mode and the fax mode by an external input signal, a mux control signal is applied to the switching circuit to connect to any one of the two data communication channels available. Switching the multiplexers to control the multiplexers so as to control the multiplexers so that the voice call is disconnected while the fax modem is connected to the currently connected data communication channel when the telephone mode is switched to the fax mode during the voice call. Telephone / fax transceiver of the fax system characterized in that it further comprises a control unit. The method of claim 1, wherein the digital communication network, Telephone / fax transceiver of a facsimile system, characterized in that it is an Integrated Service Digital Network (ISDN). The method of claim 1, wherein the switching circuit unit, A first resistor, a first capacitor, and a second resistor which are serially connected to a transmitting unit of the fax modem to determine a gain level for the analog modem signal when the analog modem signal is transmitted, and simultaneously provide a current path; ; A third resistor connected to the receiving portion of the fax modem to determine a gain level for the analog modem signal when the analog modem signal is received and to provide a current path; A second capacitor and a fourth resistor sequentially connected to the transmitter of the telephone handset to determine a gain level for the analog voice signal when the analog voice signal is transmitted and to provide a current path; A fifth resistor connected to the receiver of the telephone handset to determine a gain level for the analog voice signal when the analog voice signal is received and to provide a current path; A first multiplexer having a first switching contact connected to said second resistor, a second switching contact connected to said fourth resistor, and a main switching terminal connected to a first transmit input terminal of said first codec; A first switching contact is connected to the common contact of the fourth resistor and the second switching contact of the first multiplexer, and a second switching contact is connected to the common contact of the second resistor and the first switching contact of the first multiplexer A second multiplexer having a main switching terminal connected to a first transmission input terminal of the second codec; A third multiplexer having a first switching contact connected to the third resistor, a second switching contact connected to the fifth resistor, and a main switching terminal connected to the first receiving main switching terminal RxO of the first codec; Wow; A first switching contact is connected to the common contact of the fifth resistor and the second switching contact of the third multiplexer, and a second switching contact is connected to the common contact of the third resistor and the first switching contact of the third multiplexer A fourth multiplexer having a main switching terminal connected to a first receive output terminal of the second codec; One side is connected to the common contact between the main switching terminal of the first multiplexer and the first transmission input terminal of the first codec, and the other side is connected to the second transmission input terminal of the first codec to connect the first switching contact of the first multiplexer. Or a sixth resistor operating as a parameter for determining a gain level of the analog modem signal or the analog voice signal input to the second switching contact; A seventh resistor connected at one side to a common contact between the sixth resistor and a second transmit input terminal of the first codec, and at another side connected to a common contact terminal of the main switching terminal of the third multiplexer and a receive output terminal of the first codec and; One side is connected to the common contact between the main switching terminal of the second multiplexer and the first transmission input terminal of the second codec, and the other side is connected to the second transmission input terminal of the second codec to connect the first switching contact of the second multiplexer. Or an eighth resistor operating as a parameter for determining a gain level of the analog modem signal or the analog voice signal input to a second switching contact; A ninth resistor connected at one side to a common contact between the eighth resistor and a second transmit input terminal of the second codec, and at the other end connected to a common contact point of a main switching terminal of the fourth multiplexer and a receive output terminal of the second codec Telephone / fax transceiver of the fax system, characterized in that consisting of. The method of claim 5, And the fourth resistor has a resistance value relatively smaller than the eighth resistor, and the sixth resistor has the same resistance value as the second resistor. 6. The method of claim 5, wherein the third resistance has a resistance value equal to the internal resistance measured at the first receive output terminal of the first codec, and the fifth resistance is the internal measure measured at the first receive output terminal of the second codec. Telephone / fax transceiver of a fax system, characterized in that it has a resistance value relatively smaller than the resistance value.