WO2001069857A1

WO2001069857A1 - Data communication network system using a portion of pstn and signal processing apparatus used therein

Info

Publication number: WO2001069857A1
Application number: PCT/KR2001/000385
Authority: WO
Inventors: Woon Young Lee; Cha Yeol Jung; Seok Kyu Kang
Original assignee: Boo Yang Telecom Co., Ltd
Priority date: 2000-03-13
Filing date: 2001-03-13
Publication date: 2001-09-20
Also published as: AU3957501A

Abstract

Both a telephone and a high rate (10Mbps) data communication are amplified, equalized, mixed, divided and switched to get a long distance transmissibility. A central control unit (31) of a ISP's hub (332) and, a subscriber device (32) connected to a subscriber's PC (342) are connected with each other through an indoor extension (35) or a pair of copper wires for telephone. A transmitter (311 or 321) for transmitting a signal through indoor extensions, and a receiver (312 or 322) for receiving through an indoor extension, respectively. A switching controller (317 or 327) is provided to switch on or off in alteration the switch (315 or 325) of the transmitter (311 or 321) and, the switch (316 or 326) of the receiver (312 or 322) so that a transmission signal is not to be interfered with a reception signal when passing through the indoor extension (35) of the PSTN. A mixer (318 or 328) for mixing a voice signal and a data signal with each other to transmit through the indoor extension (35) and, a divider (319 or 329) for dividing a mixed signal received through the indoor extension (35) into a voice signal and a data signal, respectively.

Description

DATA COMMUNICATION NETWORK SYSTEM USING A PORTION OF PSTN AND SIGNAL PROCESSING APPARATUS USED THEREIN

TECHNICAL FIELD

The present invention relates to a network used both as a data network and a telephone network, more particularly to a data network for enabling to transmit data in a long distance through a pair of copper wires for telephone. The present invention also relates to an apparatus for mixing and dividing signals in the data network.

BACKGROUND OF THE INVENTION

A conventional PSTN (Public Switched Telephone Network) is used in transmitting data as well as a telephone call in DSLs (Digital Subscriber Line) such as an ADSL (Asymmetric Digital Subscriber Line), a HDSL (High bit rate Digital Subscriber Line), a SDSL (Single line Digital Subscriber Line) a VDSL (Very high data rate Digital Subscriber Line). The ADSL is developed for internet access means, a VOD (Video On Demand) system, a multimedia system and a remote education system. The HDSL is used in accessing to either a WAN (Wide Area Network) or a LAN (Local Area Network) graded with Tl and/or El. The SDSL is compared with the HDSL, while the VDSL is compared with the ADSL.

A DSL type of data network serves both data and telephone communications using a central control unit installed in a telephone exchange. Since the central control unit is installed in the telephone exchange, a data network service provider cannot avoid to be subjected to a telephone network service provider with a very high rental on telephone circuits burdened. More over, some of them, e.g., ADSL and VDSL serve in an asynchronous mode, by which the transmission rate upon uploading differs from that upon downloading.

Thus, most data network service providers wish to construct their own backbone network although they construct an indoor extension of their data network using a telephone network. An ISP (Internet Service Provider) constructs his data network using a backbone network terminating at a communication control room, in which a MDF (Main Distribution Frame) and a IDF (Intermediate Distribution Frame) are arranged, of an apartment house or an office building, and an indoor extension of PSTN (Public Switched Telephone Network) extending from the communication control room to a subscribers' terminals. In this network, a central control unit arranged in the communication control room mixes data signals from Internet with voice signals from PSTN to transmit to subscribers, and divides signals from subscribers into a data signal and a voice signal to transmit to Internet and PSTN, respectively. A subscriber device divides signals from the central control unit into a data signal and a voice signal to transmit to a PC (Personal Computer) and a telephone, respectively, and mixes data signals from a PC and data signals from a telephone to transmit to the central control unit.

Figure 1 shows one of these conventional data networks, which is referred to as T-LAN. T-LAN data network 10 has a central control unit 11 and a subscriber device 12. Both the central control unit 11 and the subscriber device 12 have two HPFs (High Pass Filters) 111 and 112 and, 121 and 122, respectively. Voice signals from PSTN 131 are transmitted through the control unit 11 and the subscriber device 12 to a telephone 141. Voice signals from the telephone 141 are transmitted through the subscriber device 12 and the central control unit 11 to PSTN 131. Data signals from the PC 142 are mixed with voice signals from the telephone 141 at the subscriber device 12 to transmit through a pair of lines of indoor extension to the central control unit 11. Data signals divided at the central control unit 11 are transmitted to an internet hub 132 connected to Internet. Data signals from the internet hub 132, however, are not mixed with voice signals from PSTN 131 and transmitted through a separate pair of lines to a PC 142 directly. Both a first HPF 111 of the central control unit 11 and a first HPF 121 of the subscriber device 12 act as a filter, through which voice signals are allowed to pass but data signals are prevented from passing, respectively. Both a second HPF 112 of the central control unit 11 and a second HPF 122 of the subscriber device 12 act as a filter, through which data signals are allowed to pass but voice signals are prevented from passing, respectively. Since the central control unit 1 1 and the subscriber device 12 are designed in consideration of filtering, they have only a short transmittable distance and operate at asymmetrical transmission rates. Moreover, the T-LAN data network requiring a 4-lines wide can not serve a subscriber with two lines of indoor extension remained. Another data network in consideration of shortcomings of the T-LAN data network 10 is shown in Figure 2. The data network 20 shown in Figure 2, named Ethernet data network, comprises a central control unit 21 connected to an ISP's hub 232 and a subscriber device 22 connected to a subscriber's PC 242. At one hand, in consideration of node extensibility, there Eire lOBase-T Ethernet connections by an UTP (Unshielded Twisted Pair) cable having four pairs of copper lines is used to connect between the hub 232 and the central control unit 21, and between the PC 242 and the subscriber device 22 as shown in Figure 2. At the other hand, in consideration of lengthening transmittable distance, there is a 10Base-2 Ethernet connection or a 10Base-5 Ethernet connection by a coaxial cable between the central control unit 21 and the subscriber device 22. Both the central control unit 21 and the subscriber device 22 in the data network 20 basically act as an intermediate device to connect the lOBase-T Ethernet to the 10Base-2 Ethernet. The central control unit 21 has the same function and structure with those of the subscriber device 22. More specifically, they comprise an interface 214 or 224 to connect between the lOBase-T Ethernet and the 10Base-2 Ethernet, a transmitter 211 or 221 for transmitting a signal through the 10Base-2 Ethernet, a receiver 212 or 222 for receiving a signal through the 10Base-2 Ethernet and, a transmission controller 213 or 223 for preventing a transmission signal and a reception signal from interfering with each other, respectively. The transmitter 211 or 221 also acts as an equalizer for modulating a signal adjusted to the UPT cable to a signal adjusted to the coaxial cable. The receiver 212 or 222 also acts as an equalizer for modulating a signal adjusted to the coaxial cable to a signal adjusted to the UPT cable. Since the hub 232 and the PC 242 are connected by an Ethernet connection having a symmetric transmittable rate by 10 Mbps, there is obtained a symmetric and high transmission rate in the data network 20. Its transmittable distance is also lengthened using a repeater. However, there is required a coaxial cable in addition to an indoor extension for connecting a telephone 141 to a PSTN 131 in the data network 20, whereby its network cost is very high.

SUMMARY OF THE INVENTION

Therefore, the present invention is to construct a data network using a backbone network other than a PSTN and indoor extensions of the PSTN. Furthermore, the present invention is to construct a symmetric high-rate network rather than an asymmetric network having a transmission rate different from a reception rate.

The present invention is also to construct a data network in which a long distance transmission through a pair of copper wires for telephone is possible. According to the present invention, a network comprising a data network incorporated with PSTN is provided. This network consists of a backbone network comprising a plurality of telephone exchanges and a plurality of indoor extensions. Some of the indoor extensions are used by the data network in common. Each indoor extension consists of a pair of copper wires for telephone. An end of the indoor extension is connected to a hub of the data network through a central control unit while the other end of the indoor extension is connected to an indoor subscriber device. Both the central control unit and the subscriber device are adapted to mix a voice signal and a data signal to transmit through the indoor extension. Both the central control unit and the subscriber device are also adapted to divide a mixed signal received through the indoor extension into a voice signal and a data signal.

The network data network may be incorporated into Internet. Preferably, both the central control unit and the subscriber device comprise a transmitter amplifying a signal to be properly transmitted through a pair of copper wires for telephone, a receiver converting a signal received through the pair of copper wires for telephone to be properly processed at the next block, a transmission controller preventing an upstream signal and a downstream signal from simultaneously applied to the pair of copper wires for telephone, a mixer for mixing a signal through the PSTN and a signal through the data network with each other and, a divider for dividing a mixed signal into the original signals through the PSTN and the data network. It is preferred that the transmission controller comprises a first switch for switching on or off a line connected to the transmitter, a second switch for switching on or off a line connected to the receiver and, a switching controller for controlling switching on and off the first switch and the second switch.

It is also preferred that the switching controller operates to switch on the first switch and off the second switch upon receiving a signal through the interface and to switch off the first switch and on the second switch upon receiving a signal through the divider.

In another aspect of the invention, a LAN (Local Area Network) for connecting a hub of Internet to a subscriber's terminal is provided. The LAN comprises a central control unit connected to the hub and a subscriber device connected to the terminal. Both the central control unit and the subscriber device are connected through a pair of copper wires for telephone. Both the central control unit and the subscriber device comprise a transmitter amplifying a signal to be properly transmitted through a pair of copper wires for telephone, a receiver converting a signal received through the pair of copper wires for telephone to be properly processed at the next block and, a transmission controller preventing an upstream signal and a downstream signal from simultaneously applied to the pair of copper wires for telephone.

Preferably, the pair of copper wires for telephone is a part of indoor extensions of a PSTN, in which both the central control unit and the subscriber device comprise a mixer for mixing a signal through the PSTN and a signal through a data network with each other and, a divider for dividing a mixed signal into the original signals through the PSTN and the data network.

Another aspect of the invention, a signal processor used in data communication is provided. The signal processor comprises a transmitter amplifying a signal to be properly transmitted through a pair of copper wires for telephone, a receiver converting a signal received through the pair of copper wires for telephone to be properly processed at the next block, a transmission controller preventing an upstream signal and a downstream signal from simultaneously applied to the pair of copper wires for telephone, a mixer for mixing a signal through the PSTN and a signal through the data network with each other and, a divider for dividing a mixed signal into the original signals through the PSTN and the data network. Another aspect of the invention, a method for communicating through Internet using the data network is provided. The method comprises transmitting for a data signal through a hub of Internet to a transmitter to a central control unit. The data signal is equalized by amplifying a band frequency of the data signal so that the data signal countervails the frequency transmissibility of a pair of copper wires for telephone. An equalized signal is transmitted to a mixer of the central control unit. Upon receiving a voice signal from the PSTN, the equalized data signal and the voice signal are mixed into a mixed signal. Both the equalized data signal and a mixed signal are transmitted through a pair of copper wires for telephone to a subscriber device. Preferably, the method further comprises receiving a data signal or a mixed signal from the subscriber device through the pair of copper wires for telephone.

The mixed signal is divided into a data signal if the mixed data signal is received from the subscriber device. The divided data signal is transmitted through a hub to Internet.

According to the present invention, any transmittal media is not required since indoor extensions of the PSTN are used, whereby Internet is expanded to each home at low cost. In light of a T-LAN using a 4-lines wide cable, the network using a 2-lines wide cable according to the present invention is very cheap. Data is transmitted at high rate without modulation and demodulation only by amplifying and equalizing, whereby a transmission distance is significantly increased. Both a central control unit and a subscriber device used in the present invention have a compact circuit, respectively. A subscriber can enjoy a high-rate data communication along with a voice communication using the network according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Several preferred embodiments of the present invention will be explained with reference to the accompanying drawings, in which:

Figure 1 shows a block diagram for explaining a data network associated into Internet using indoor extensions of a PSTN in common,

Figure 2 shows a block diagram for explaining a lOBase-T network using a coaxial cable of a conventional 10Base-2 network and, Figure 3 shows a block diagram for explaining an embodiment of the data network according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the attached drawings, a preferred embodiment of the data network according to the present invention will be explained. Herein, an equalizer is a device for deliberately deforming a transmission signal by amplifying only a partial band frequency of the transmission signal so that the transmission signal countervails the frequency transmissibility of a transmittal medium. The equalizer is selected from conventional equalizers with no constraint.

A mixer is a device for mixing a voice signal and a data signal to transmit through a common transmittal medium simultaneously. The mixer is selected from conventional mixers with no constraint.

A divider is a device for dividing a mixed signal through the common medium into a voice signal and a data signal. The divider is selected from conventional dividers with no constraint. Herein, a voice signal means not only an electric signal converted from a sonic signal but also any electric signal through the PSTN or through a 2-lines wide cable for telephone. In other words, the voice signal also comprises a data signal output from a facsimile or a data signal controlled by a modem (MOdulator/DEModulator) to transmit through a 2-lines wide cable for telephone. A data signal, however, is to be narrowly interpreted as a signal transmitted through a conventional cable for Internet.

Figure 3 shows a block diagram for explaining a preferred embodiment of the data network according to the present invention.

As shown in Figure 3, the data network 30 in this embodiment comprises a central control unit 31 of a ISP's hub 332 and, a subscriber device 32 connected to a subscriber's PC 342. Both the central control unit 31 and the subscriber device 32 are connected with each other through an indoor extension 35 of the PSTN or a pair of copper wires for telephone.

The central control unit 31 and the subscriber device 32 have equational -more precisely, symmetric- constituents. The central control unit 31 and the subscriber device 32 have an interface 314 or 324 for communicating with an Ethernet such as a lOBase-T Ethernet, 10Base-2 Ethernet or 10Base-5 Ethernet, respectively.

The central control unit 31 and the subscriber device 32 comprise a transmitter 311 or 321 for transmitting a signal through indoor extensions of PSTN, and a receiver 312 or 322 for receiving through an indoor extension of PSTN, respectively. The transmitter 311 or 321 also acts as a equalizer for converting a signal equalized to fit to an Ethernet transmittal medium such as a coaxial cable or an UPT cable into a corresponding signal equalized to fit to an indoor extension of the PSTN. The receiver 312 or 322 also acts as a equalizer for converting a signal equalized to fit to an indoor extension of the PSTN into a corresponding signal equalized to fit to an Ethernet transmittal medium such as a coaxial cable or an UPT cable.

The transmitter 311 or 321 and the receiver 312 or 322 are provided with a switch 315, 316, 325 or 326 at an upstream or downstream position. A switching controller 317 or 327 is provided to switch on or off in alteration the switch 315 or 325 of the transmitter 311 or 321 and, the switch 316 or 326 of the receiver 312 or 322 so that a transmission signal is not to be interfered with a reception signal when passing through the indoor extension 35 of the PSTN.

The central control unit 31 and the subscriber device 32 also comprise a mixer 318 or 328 for mixing a voice signal and a data signal with each other to transmit through the indoor extension 35 of the PSTN and, a divider 319 or 329 for dividing a mixed signal received through the indoor extension 35 of the PSTN into a voice signal and a data signal, respectively.

Hereinafter, a method for processing a signal transmitted through data network in this embodiment will be explained. Firstly, processes conducted in the central control unit 31 are explained.

A downloaded data signal is received through the interface 314 from the hub 332 connected to Internet 333. As mentioned above, the hub 332 is connected to the interface 314 through one of lOBase-T Eathernet, 10Base-2 Eathernet and 10Base-5 Eathernet selectively using a UTP cable or a coaxial cable in consideration of the number of nodes supported by the hub 332 and a required transmission distance. A signal received through the interface 314 is transferred through the first switch 315 to the transmitter 311. The equalizer combined into the transmitter 311 acts to equalize the data signal in consideration of the frequency transmissibility of the indoor extension 35 of the PSTN before transferring to the mixer 318 that transmits the data signal through the indoor extension 35 to the subscriber device 32 after mixing the data signal with the voice signal received from the PSTN 331.

Also, the central control unit 31 receives a mixed signal through the indoor extension 35 from the subscriber device 32. The divider 319 acts to divide the mixed signal into a voice signal and an uploaded data signal. The voice signal divided by the divider 319 is directly released to the PSTN 331, while the data signal is transferred to the receiver 312. The equalizer combined into the receiver 312 acts to equalize the data signal in consideration of the frequency transmissibility of the UPT or coaxial cable of the Ethernet before transferring through the second switch 316 to the interface 314 that transmits the data signal through the hub 332 of the Ethernet.

The interface 314 transfers data components extracted from the downloaded data signal to the switching controller 317 that switches on the first switch 315 to transfer downloaded data to the transmitter 311 if there is no uploaded data received by the receiver 312. If any uploaded data is received by the receiver 312, the first switch 315 is switched off to prevent the downloaded data transferred through the transmitter 311 to the indoor extension 35 from being interfered with the uploaded data. Since the equalizer combined into the transmitter 311 is connected to the equalizer combined into the receiver 312, the downloaded data signal is transferred from the transmitter 311 to the receiver 312, while the uploaded data signal is transferred from the receiver 312 to the transmitter 311. In other words, the switching controller 317 switches off the second switch 316 to block the uploaded data signal and switches on the first switch 315 to transmit the downloaded data signal when the downloaded data signal is inputted, while switching off the first switch 315 to block the downloaded data signal and switching on the second switch 316 to receive the uploaded data signal when the uploaded data signal is inputted.

At the interface 314 of the central control unit 31, a transmission line link signal for checking the line link status is transferred from a transmission side to a reception side. If it is failed to transfer the transmission line link signal because of an excessive transmission data, the reception side of the interface 314 is initialized as deciding as the line link is considered to be off. In order to avoid this initialization, the switching controller 317 transfers the transmission line link signal to the reception side of the interface 314 when the transmission data is excessive. Secondly, processes conducted in the subscriber device 32 are explained.

A downloaded data signal is received through the interface 324 from the PC 342. The PC 342 is connected to the interface 324 through lOBase-T Eathernet in general, 10Base-2 Eathernet or 10Base-5 Eathernet in occasional or, directly installed on an expansion bus of the PC 342. A signal received through the interface 324 is transferred through the first switch 325 to the transmitter 321. The equalizer combined into the transmitter 321 acts to equalize the data signal in consideration of the frequency transmissibility of the indoor extension 35 of the PSTN before transferring to the mixer 328 that transmits the data signal through the indoor extension 35 to the central control unit 31 after equalized in consideration of the frequency transmissibility of the indoor extension 35.

Also, the subscriber device 32 receives a mixed signal through the indoor extension 35 from the central control unit 31. The divider 329 acts to divide the mixed signal into a voice signal and an uploaded data signal. The voice signal divided by the divider 329 is directly transferred to the telephone 341, while the data signal is transferred to the receiver 322. The equalizer combined into the receiver 322 acts to equalize the data signal in consideration of the frequency transmissibility of the UPT cable of the Ethernet before transferring through the second switch 326 to the interface

324 that transmits the data signal through the Ethernet to the PC 342.

The interface 324 transfers data components extracted from the uploaded data signal to the switching controller 327 that switches on the first switch 325 to transfer uploaded data to the transmitter 321 if there is no uploaded data received by the receiver 322. If any downloaded data is received by the receiver 322, the first switch

325 is switched off to prevent the uploaded data transferred through the transmitter 321 to the indoor extension 35 from being interfered with the downloaded data. Since the equalizer combined into the transmitter 321 is connected to the equalizer combined into the receiver 322, the uploaded data signal is transferred from the transmitter 321 to the receiver 322. In other words, the switching controller 327 switches off the second switch 326 to block the downloaded data signal and switches on the first switch 325 to transmit the uploaded data signal when the uploaded data signal is inputted, while switching off the first switch 325 to block the uploaded data signal and switching on the second switch 326 to receive the downloaded data signal when the downloaded data signal is inputted.

At the interface 324 of the subscriber device 32, a transmission line link signal for checking the line link status is transferred from a transmission side to a reception side. If it is failed to transfer the transmission line link signal because of an excessive transmission data, the reception side of the interface 314 is initialized as deciding as the line link is considered to be off. In order to avoid this initialization, the switching controller 327 transfers the transmission line link signal to the reception side of the interface 324 when the transmission data is excessive.

During transmission of the uploaded data packet, the downloaded data packet is on standby at a buffer of the hub 332, while the uploaded data packet is on standby at a buffer of the PC 342 during transmission of the downloaded data packet. This transmission control mode is not specifically explained because it is well known. Anyway, data communication should be more smooth if the interfaces of the central control unit and the subscriber device are provided with a buffer for storing data packets on standby.

The present invention embodies a data network and, a signal mixer and a signal divider used in the data network, by which a long distance communication using a pair of copper wires for telephone is possible.

Although this invention is explained based on a preferred embodiment, the embodiment is only to exemplify but not to limit the present invention. To a skilled person in this art, it will be apparent that any change, alteration or modulation from the embodiment without departing from the technical idea of the present invention can be easily made. Attached claims should be interpreted as comprehension of such change, alteration or modulation.

Claims

CLAIMS What is claimed is:

1. A network comprising a data network incorporated with PSTN consisting of a backbone network comprising a plurality of telephone exchanges and a plurality of indoor extensions, some of the indoor extensions being used by the data network in common, each indoor extension consisting of a pair of copper wires for telephone, wherein an end of the indoor extension is connected to a hub of the data network through a central control unit while the other end of the indoor extension is connected to an indoor subscriber device, both the central control unit and the subscriber device adapted to mix a voice signal and a data signal to transmit through the indoor extension and, both the central control unit and the subscriber device adapted to divide a mixed signal received through the indoor extension into a voice signal and a data signal.

2. The network according to Claim 1, characterized in that the data network is incorporated into Internet.

3. The network according to Claim 1 or 2, characterized in that both the central control unit and the subscriber device comprise: a transmitter amplifying a signal to be properly transmitted through a pair of copper wires for telephone; a receiver converting a signal received through the pair of copper wires for telephone to be properly processed at the next block; a transmission controller preventing an upstream signal and a downstream signal from simultaneously applied to the pair of copper wires for telephone; a mixer for mixing a signal through the PSTN and a signal through the data network with each other and; a divider for dividing a mixed signal into the original signals through the PSTN and the data network.

4. The network according to Claim 3, characterized in that the transmission controller comprises a first switch for switching on or off a line connected to the transmitter, a second switch for switching on or off a line connected to the receiver and, a switching controller for controlling switching on and off the first switch and the second switch.

5. The network according to Claim 4, characterized in that the switching controller operates to switch on the first switch and off the second switch upon receiving a signal through the interface and to switch off the first switch and on the second switch upon receiving a signal through the divider.

6. A LAN for connecting a hub of Internet to a subscriber's terminal comprising a central control unit connected to the hub and a subscriber device connected to the terminal, both the central control unit and the subscriber device connected through a pair of copper wires for telephone, wherein both the central control unit and the subscriber device comprise a transmitter amplifying a signal to be properly transmitted through a pair of copper wires for telephone, a receiver converting a signal received through the pair of copper wires for telephone to be properly processed at the next block and, a transmission controller preventing an upstream signal and a downstream signal from simultaneously applied to the pair of copper wires for telephone.

7. The LAN according to Claim 6, wherein the pair of copper wires for telephone is a part of indoor extensions of a PSTN, characterized in that both the central control unit and the subscriber device comprise a mixer for mixing a signal through the PSTN and a signal through a data network with each other and, a divider for dividing a mixed signal into the original signals through the PSTN and the data network.

8. The LAN according to Claim 6 or 7, characterized in that the transmission controller comprises a first switch for switching on or off a line connected to the transmitter, a second switch for switching on or off a line connected to the receiver and, a switching controller for controlling switching on and off the first switch and the second switch.

9. The LAN according to Claim 8, characterized in that the switching controller operates to switch on the first switch and off the second switch upon receiving a signal through the interface and to switch off the first switch and on the second switch upon receiving a signal through the divider.

10. A signal processor used in data communication comprising: a transmitter amplifying a signal to be properly transmitted through a pair of copper wires for telephone; a receiver converting a signal received through the pair of copper wires for telephone to be properly processed at the next block; a transmission controller preventing an upstream signal and a downstream signal from simultaneously applied to the pair of copper wires for telephone; a mixer for mixing a signal through the PSTN and a signal through the data network with each other and; a divider for dividing a mixed signal into the original signals through the PSTN and the data network.

11. The signal processor according to Claim 10, characterized in that the transmission controller comprises a first switch for switching on or off a line connected to the transmitter, a second switch for switching on or off a line connected to the receiver and, a switching controller for controlling switching on and off the first switch and the second switch.

12. The signal processor according to Claim 11, characterized in that the switching controller operates to switch on the first switch and off the second switch upon receiving a signal through the interface and to switch off the first switch and on the second switch upon receiving a signal through the divider.

13. A method for communicating through Internet using the data network according to one of Claims 1 through 5, comprising steps of; transmitting for a data signal through a hub of Internet to a transmitter to a central control unit; equalizing the data signal by amplifying a band frequency of the data signal so that the data signal countervails the frequency transmissibility of a pair of copper wires for telephone; transmitting an equalized signal to a mixer of the central control unit; mixing the equalized data signal and the voice signal into a mixed signal upon receiving a voice signal from the PSTN and; transmitting both the equalized data signal and a mixed signal through a pair of copper wires for telephone to a subscriber device.

14. The method according to Claim 13, characterized in that the method further comprises steps of: receiving a data signal or a mixed signal from the subscriber device through the pair of copper wires for telephone; dividing the mixed signal into a data signal if the mixed data signal is received from the subscriber device and, transmitting the divided data signal through a hub to Internet.