JP2002261968A - Telephone switching system and terminal device used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a method for the Internet telephone and the conventional telephone by using the same terminal makes a telephone terminal daily use useless, and that a IP telephone system available when power is on is not effective to an ordinary modem a constantly connected. SOLUTION: When a communication is made with the outside using a public switched network 31 such as the Internet, a circuit capturing control signal is outputted from a modem signal processing section 13 to a circuit/sound-source switching section 15. If the telephone terminal 32 is turned into an off-hook state during the use of the modem, the circuit/sound-source switching section 15 connects the telephone terminal 32 and a sound input/output section 17 to make a transmitter and receiver of the telephone terminal 32 be used as a microphone/speaker, enabling the Internet telephoning. When the modem is not in use, if the telephone terminal 32 is turned into an off-hook state, the circuit/sound-source switching section 15 connects the telephone terminal 32 to the public switched network 31 to make the telephone terminal 32 be used as an ordinary telephone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone switching system and a terminal device used therefor, and more particularly to a telephone switching system usable for both a personal computer telephone and a normal telephone and a terminal device used therefor.

[0002]

2. Description of the Related Art Conventionally, personal computers (PCs) perform voice communication in real-time via the Internet via an Internet connection by exchanging voice of an Internet telephone by connecting a speaker and a microphone to a sound source device connected to the personal computers. Then, a method of using them is adopted. However, in this method, since the sound is heard from the speakers to the surroundings, private conversation cannot be performed.

[0003] Therefore, power is supplied to a telephone terminal device which is conventionally used on a daily basis, two-line / four-line conversion is performed, and transmission and reception signals are separated and connected to a sound source device provided in a personal computer. There has been known a telephone switching system in which a received voice signal is switched between output to a speaker output terminal of a sound source device of a personal computer and output to a speaker unit of a telephone terminal device according to a state of a hook switch of the telephone terminal device. (JP-A-2000-270123).

[0004] In the field of packet network telephone equipment which enables voice data to be communicated on a packet network, a telephone is connected to a public switched telephone network (PSTN) line according to the on / off state of the power supply of the equipment. Alternatively, a device that includes a fallback switch connected to one of the lines of a packet network and is arbitrarily selectable is also conventionally known (JP-A-11-355474).

[0005]

However, the method of making an Internet telephone call and a normal telephone call on the same terminal requires a large-scale apparatus and wastes a telephone terminal used daily by most households. become. Also, Japanese Patent Laid-Open No. 2000-
In the system disclosed in Japanese Patent No. 270123, private conversation can be performed, but a telephone terminal can only be used in place of a microphone and a speaker, and a normal telephone call cannot be made using the terminal.

Further, in the system described in Japanese Patent Application Laid-Open No. 11-355474, the PSTN is
The line and packet network are switched, and when the power is turned on, the IP telephone can be used. In this case, it is assumed that network communication is performed. Therefore, it is effective for a cable modem or the like. It is not a valid technology for ordinary modems used in environments where it is not possible.

[0007] The present invention has been made in view of the above points,
It is an object of the present invention to provide a telephone switching system which can be used by switching between a personal computer telephone and a normal telephone with the terminal and a terminal device used for the system.

It is another object of the present invention to provide a telephone switching system capable of switching between a personal computer telephone and a normal telephone by using a normal modem used in an environment where connection is not always possible, and a terminal device used therefor. It is in.

[0009]

In order to achieve the above object, a telephone switching system according to the present invention switches a connection of a normal telephone terminal to a public line network, thereby making a telephone connection based on interconnection by a communication network protocol. A telephone switching system for switching between communication and telephone communication by circuit switching, wherein a sound section for inputting and outputting a sound signal used for telephone communication by interconnection and a sound signal from the sound section are generated, and an external voice is output. Sound source means for picking up sound and inputting it to the sound unit, first detecting means for detecting an off-hook state of the telephone terminal, and second detecting means for detecting whether the modem unit is in use by connecting to a public line network. When the detecting means and the first and second detecting means detect that the telephone terminal is in an off-hook state and the modem section is in use, The telephone unit is connected to the telephone terminal, and the telephone communication of the telephone terminal is performed by interconnecting using the handset of the telephone terminal as a microphone and a speaker. The telephone terminal is in an off-hook state and the modem unit is not in use. And a switching means for connecting the telephone terminal to a public line network and using the telephone terminal for telephone communication by circuit switching.

According to the present invention, when it is detected that the telephone terminal is in an off-hook state and the modem unit is being used for the Internet or the like, the sound unit is connected to the telephone terminal and the handset of the telephone terminal is connected. The telephone terminal is connected to the public line network when it is detected that the telephone terminal is in an off-hook state and the modem unit is not in use by using the telephone terminal as a microphone and a speaker. The normal use of the telephone terminal can be performed.

In order to achieve the above object, according to the present invention, the switching means is provided by the first and second detecting means, wherein the telephone terminal is in an on-hook state and the modem unit is in use. When the sound source is detected, the sound section is disconnected from the telephone terminal and connected to the sound source means, and the sound source means is used for voice input / output to perform telephone communication by interconnection.

Further, in order to achieve the above object, the present invention is a telephone switching system for switching between telephone communication by interconnection using a communication network protocol and telephone communication by circuit switching, and is used in telephone communication by interconnection. A sound section for inputting and outputting a sound signal, a sound source means for generating a sound signal from the sound section, collecting external sounds, and inputting the sound to the sound section; A communication unit for performing wireless communication between the mobile phone, a first detection unit for detecting an off-hook state of the mobile phone based on a signal input from the mobile phone via the communication unit, and a modem unit connected to a public network. Second detecting means for detecting whether or not the apparatus is in use;
And when the second detecting means detects that the mobile phone is in an off-hook state and the modem section is in use, the sound section is connected to the mobile phone via the communication means, and the handset of the mobile phone is connected. As a microphone and a speaker, perform telephone communication by interconnection. When it is detected that the mobile phone is in the on-hook state and the modem section is in use, the sound section is switched to the sound source means and connected. It is characterized in that the means is used for voice input / output to perform telephone communication by interconnection.

According to the present invention, when it is detected that the mobile phone is in the off-hook state and the modem section is in use, the sound section is connected to the mobile phone via the communication means. The handset can be used as a microphone and a speaker for telephone communication by interconnection such as the Internet.

In order to achieve the above object, a terminal device of the present invention is a terminal device provided in a personal computer for connecting a modem unit to a public line network and performing telephone communication by interconnection, A sound section for inputting and outputting a sound signal, a sound source means for generating a sound signal from the sound section, converting an external voice into a sound signal and inputting the sound signal to the sound section, and an off-hook of an externally connected telephone terminal A telephone terminal is provided by a first detecting means for detecting a state, a second detecting means for connecting a modem unit to a public line network to detect whether the telephone is in use, and the first and second detecting means. When it is detected that the modem section is in use in the off-hook state and the modem section is in use, the sound section is connected to the telephone terminal, and the telephone terminal is used as a microphone and a speaker for interconnection. If it is detected that the telephone terminal is in an off-hook state and the modem unit is not in use, the telephone terminal is switched to a public line network and connected, and the telephone terminal is normally connected. And switching means used for telephone communication by circuit switching.

According to the present invention, when it is detected that the telephone terminal is in an off-hook state and the modem unit is in use, the sound unit is connected to the telephone terminal to connect the handset of the telephone terminal to a microphone and a microphone. Using the speaker as a speaker to perform telephone communication by interconnection, the telephone terminal is in an off-hook state,
And when it is detected that the modem is not in use,
The telephone terminal is switched to a public line network and connected, and the telephone terminal is used for telephone communication by ordinary circuit switching.

According to another aspect of the present invention, there is provided a terminal device provided in a personal computer for connecting a modem unit to a public line network and performing telephone communication by interconnection. A sound section for inputting and outputting a sound signal, a sound source section for generating a sound signal from the sound section, converting an external sound into a sound signal and inputting the sound signal to the sound section, and a communication for wirelessly communicating with the mobile phone. Means, first detecting means for detecting an off-hook state of the mobile phone based on a signal inputted from the mobile phone via the communication means, and detecting whether the modem section is in use by connecting to a public line network. Second detecting means for performing
And when the second detecting means detects that the mobile phone is in an off-hook state and the modem section is in use, the sound section is connected to the mobile phone via the communication means, and the handset of the mobile phone is connected. When the mobile phone is in the on-hook state and the modem section is detected as being in use, the sound section is switched to the sound source means and connected to the sound source section. Switching means for performing telephone communication by interconnection using the means for voice input / output.

According to the present invention, when it is detected that the mobile phone is in the off-hook state and the modem section is in use, the sound section is connected to the mobile phone via the communication means. Using the handset as a microphone and a speaker, telephone communication by interconnection can be performed.

[0018]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a telephone switching system according to the present invention and a terminal device used therein. In FIG. 1, a terminal device 10 is provided in a personal computer 20, and connected to an I / O bus 21 in the personal computer 20 that performs data input / output processing with a host device of the personal computer 20. Part 1
And 2.

The modem section 11 includes a modem signal processing section 13 for processing a modem signal and a data access circuit section (DAA: Data Access Arrangement) 14 for processing a line.
And a line / sound source switching unit 15 for switching lines and sounds. Also, the sound unit 12
It comprises a sound signal processing section 16 connected to the I / O bus 21 for processing sound, and a sound input / output section 17 for inputting / outputting a sound source.

Outside the terminal device 10 and the personal computer 20, a telephone terminal 32, which is a general subscriber telephone, and a microphone (abbreviated as microphone) 33,
The speaker 34 is connected. In addition, the terminal device 10
Can be connected to the public line network 31. The public network 31 includes both an interconnection network such as the Internet and a circuit switching network such as a telephone network and ISDN.

Next, a schematic operation of an embodiment of the telephone switching system according to the present invention will be described with reference to FIG.
The operator uses the modem unit 11 of the personal computer 20 to
When communication with the outside is performed using the public line network 31 such as the Internet, a line capture control signal is output from the modem signal processing unit 13 and supplied to the line / sound source switching unit 15.

When the telephone terminal 32 is off-hook (when the handset is picked up) during use of the modem, the telephone terminal 32 and the sound input / output unit 17 are connected under the control of the line / sound source switching unit 15 and used daily. The handset of the telephone terminal 32 is used as a microphone / speaker to enable Internet telephone calls.

When the telephone terminal 32 is in the on-hook state when the modem is used, the line / sound source switching unit 15
, The sound input / output unit 17 is connected to the microphone 33 and the speaker 34. When the modem is not used,
When the line capture control signal is not input to the line / sound source switching unit 15 and the telephone terminal 32 goes off-hook at this time, the line / sound source switching unit 15 connects the telephone terminal 32 to the public line network 31. After connection, the telephone terminal 32 can be used as a normal telephone.

Next, the configuration and operation of the line / sound source switching unit 15, which is a main part of the present invention, will be described in more detail. FIG. 2 shows a circuit / sound source switching unit 15 as a main part of the present invention.
1 is shown together with peripheral circuits. In the figure, the same components as those of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 2, the line / sound source switching unit 15
Detects that the telephone terminal 32 is off-hook, and that the line capturing unit 41 performs connection or disconnection with the telephone terminal 32 according to whether or not a line capture control signal is input from the modem signal processing unit. A hooking detection unit 42, an AND circuit 43 that is opened when a hooking signal is input from the hooking detection unit 42, and allows a line acquisition control signal to pass therethrough, and a sound input according to a signal from the AND circuit 43. The input and output of the output unit 17 are
A line-switching hybrid circuit 45 or a line / sound switching circuit 44 for switching connection to a microphone 33 and a speaker 34 on the side, and a 2-wire 4-wire switching hybrid circuit 45
And a level conversion circuit 46 for level-converting the audio signal to a level that can be received by the telephone terminal 32.

Next, the operation of this embodiment will be described with reference to the block diagrams of FIGS. 1 and 2 and the flowchart of FIG. While the modem unit 11 is using the line, a line capture control signal is output from the modem signal processing unit 13 and controlled by software such as a modem driver and supplied to the line capture unit 41 and the AND circuit 43, respectively. When the line capture control signal is input, the line capture unit 41
Side, that is, the telephone terminal 32 and the sound unit 12 side are separated. In this state, the modem unit 11 is seizing the line, that is, the personal computer is using the public line network 31 via the modem unit 11, and the operator connects to the Internet or the like to communicate with the outside. It is in the state of going.

On the other hand, when the modem unit 11 is not using the line, no line capture control signal is output from the modem signal processing unit 13 and the line capture unit 41
It is in an initial state where the telephone terminal 32 and the sound unit 12 are connected. Therefore, depending on whether or not the line capture control signal is output from the modem signal processing unit 13, the modem unit 1
You can see if you are using 1.

Now, assuming that the user of the telephone terminal 32 lifts the handset, that is, puts the telephone in the off-hook state (step 101 in FIG. 3), the off-hook state is detected by the hooking detector 42. , A hooking signal is supplied to an AND circuit 43. At this time, as described above, it is determined whether or not the modem unit 11 is being used based on whether or not the line capture control signal is output from the modem signal processing unit 13 (step 10 in FIG. 3).
2) When the modem unit 11 is used, the line capturing unit 41 receives the line capturing control signal and
2 and the sound unit 12 side are separated, and the AND circuit 43 is in a gate "open" state.

Thus, when the telephone terminal 32 is set to the off-hook state and the modem unit 11 is used, a hooking signal is supplied to the line / sound switching circuit 44 through the AND circuit 43 to switch the line / sound. The circuit 44 is switched from side to side, and the sound input / output unit 17 is switched to a two-wire / four-wire conversion hybrid circuit 45.
(Step 103 in FIG. 3).

As a result, the input / output sound signal (voice signal) of the sound input / output unit 17 is converted into two lines by the two-wire / four-wire conversion hybrid circuit 45, and the level is converted by the telephone terminal 32 by the level conversion circuit 46. It is converted to a possible level and is input to and output from the handset of the telephone terminal 32. As a result, when the telephone terminal 32 goes off-hook while the personal computer uses the public line network 31 via the modem unit 11 and the operator is connected to the Internet or the like to communicate with the outside, the telephone terminal Function as the microphone and speaker of the handset of the handset 32 (step 10 in FIG. 3).
4). Therefore, at this time, the ordinary telephone terminal 32 can be used as an Internet telephone.

On the other hand, when the telephone terminal 32 is off-hook, if the modem unit 11 is not used, step 102
When the determination is made in the above, the line capture control signal is not output from the modem signal processing unit 13, and the line capture unit 41
That is, the telephone terminal 32 is in the initial state of connection, and the AND circuit 43 is in the gate "closed" state.

Thus, when the telephone terminal 32 is turned off-hook and the modem unit 11 is not in use, the hooking signal is transmitted to the line / sound switching circuit 4.
4, the line / sound switching circuit 44 is switched from side to side, and the telephone terminal 32 is connected to the public line network 312 via the line capturing unit 41.
The telephone terminal 32 is used as a normal telephone terminal (step 105 in FIG. 3).

When the modem unit 11 is in use and the telephone terminal 32 is not off-hook, the hooking signal is transmitted to the line / sound switching circuit 4 as described above.
4, the line / sound switching circuit 44 is switched from side to side.
7 is supplied to a speaker 34 through a line / sound switching circuit 44 to be sounded, and the sound picked up by the microphone 33 is converted into a sound signal. Is input to the sound input / output unit 17 through the.

As described above, in the present embodiment, the operator uses the modem unit 11 of the personal computer to make the public line network 31 accessible.
The telephone terminal 32 that is used on a daily basis can be automatically switched and used as an Internet telephone when connected to the Internet via the Internet, and as a normal telephone when not using the Internet. Further, in this embodiment, the use of the telephone terminal 32 or the microphone 33 and the speaker 34 is triggered by whether or not the modem unit 11 is used, and the modem unit 11 used in an environment where connection is not always possible. You can also use an Internet phone or a normal phone by using a personal computer that uses.

Next, another embodiment of the present invention will be described. FIG. 4 is a block diagram showing another embodiment of the telephone switching system and the terminal device used therein according to the present invention. In the figure, the same components as those of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 4, the terminal device 50
Is provided in the personal computer, and is connected to the I / O bus 21 in the personal computer.
And 2.

The modem section 51 includes a modem signal processing section 13 for processing a modem signal and a data access circuit section (DAA: Data Access Arrangement) 14 for processing a line.
, A line / sound source switching unit 15 for switching between a line and a sound, an A / D conversion unit 53, and a wireless unit 59.

The terminal device 50 is configured so that the wireless unit 54 can be connected to a normal mobile phone 55. The cellular phone 55 is a portable cellular phone (PHS) or a Bluetooth (Bluetooth) -compatible cellular phone, and wirelessly communicates with the wireless unit 54. The signal received by the wireless unit 54 is A / A.
The signal is converted into a digital signal by the D conversion unit 53 and supplied to the line / sound source switching unit 52. The A / D conversion unit 53 and the wireless unit 54 include a well-known pierf (PIAFS) or Bluetooth.
convert to a wireless output such as o.

In this embodiment, the line / sound source switching unit 52 does not have the line acquisition unit 41 as compared with the line / sound source switching unit 15 shown in FIG. When a line capture control signal indicating that the modem is being used is input from the mobile phone 55 and a signal indicating an off-hook state is input from the mobile phone 55 through the wireless unit 54 and the A / D converter 53, the sound unit 12 is set to A. / D converter 53.

Thus, the sound input from the portable telephone 55 is converted into a sound signal by the microphone of the portable telephone 55, transmitted wirelessly to the radio section 54, and further converted to an A / D converter 53 and a line / sound source switching section 52. Is input to the sound unit 12 via the. The sound signal output from the sound unit 12 is input to the A / D conversion unit 53 through the line / sound source switching unit 52, where it is converted into a digital signal, and then transmitted wirelessly from the wireless unit 54 to the mobile phone 55. Then, the sound is generated from the speaker of the mobile phone 55.

The line / sound source switching unit 52 receives a signal indicating an off-hook state from the portable telephone 55 even if the line capture control signal indicating that the modem is being used is input from the modem signal processing unit 13. 54 and the A / D converter 53, the sound unit 1
2 is connected to the microphone 33 and the speaker 34. In addition, when performing normal telephone communication, the mobile phone 55 performs communication according to the same protocol as that of the related art via a wireless base station (not shown).

As described above, according to this embodiment, when a personal computer telephone such as an Internet telephone (that is, telephone communication through interconnection by a communication network protocol) is performed using the modem unit 51, the portable telephone 55 is used.
Can be used like a cordless telephone handset,
As a result, it is possible to make a PC telephone away from the PC.

The present invention is not limited to the above embodiment. For example, in combination with an interface phone application built in a personal computer, an interface phone application is dialed from a telephone terminal. Stone) signal and automatically place it as an internet phone,
When connected to the Internet, an Internet telephone can be realized by the operation of a normal telephone terminal.

[0043]

As described above, according to the present invention,
When it is detected that the telephone terminal is in the off-hook state and the modem unit is being used for the Internet or the like, the sound unit is connected to the telephone terminal and the handset of the telephone terminal is used as a microphone and a speaker. When telephone communication by interconnection is performed, and it is detected that the telephone terminal is in an off-hook state and the modem unit is not in use, the telephone terminal is connected to a public line network and the normal operation of the telephone terminal is performed. Since no special operation is required, a normal telephone terminal or a portable telephone can be used for telephone communication by interconnection such as an Internet telephone with the same feeling as a telephone used in daily life.

According to the present invention, when it is detected that the mobile phone is in the off-hook state and the modem is in use, the sound unit is connected to the mobile phone via the communication means. Since the handset of the mobile phone is used as a microphone and a speaker to perform telephone communication by interconnection, the mobile telephone is used like a cordless telephone handset, and is connected to an Internet telephone etc. away from the personal computer. Can be used for telephone communication.

Further, according to the present invention, a telephone terminal or a microphone and a speaker are used as a trigger based on whether or not a modem section is used, and a normal modem section used in an environment where connection is not always possible. A personal computer using a telephone can select and use a telephone for telephone communication by interconnection such as an Internet telephone or a normal telephone.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of an embodiment of a line / sound source switching unit of a main part of FIG. 1;

FIG. 3 is a flowchart for explaining the operation of FIGS. 1 and 2;

FIG. 4 is a block diagram of another embodiment of the present invention.

[Explanation of symbols]

 10, 50 Terminal device 11, 51 Modem unit 12 Sound unit 13 Modem signal processing unit 14 DAA unit 15 Line / sound source switching unit 16 Sound signal processing unit 17 Sound input / output unit 20 Personal computer (PC) 21 I / O bus 31 Public Line network 32 Telephone terminal 33 Microphone 34 Speaker 41 Line capture unit 42 Hooking detection unit 43 AND circuit 44 Line / sound switching circuit 45 2-wire 4-wire conversion hybrid circuit 46 Level conversion circuit 53 A / D conversion unit 54 Wireless unit 55 Mobile Telephone

Claims (7)

[Claims] 1. A telephone switching system for switching between telephone communication by interconnection according to a communication network protocol and telephone communication by circuit switching by switching connection of a normal telephone terminal to a public line network. A sound unit for inputting and outputting a sound signal used in telephone communication by connection; sound source means for generating a sound signal from the sound unit, collecting external sound, and inputting the sound to the sound unit; A first detecting means for detecting an off-hook state of the telephone, a second detecting means for connecting a modem unit to the public network to detect whether or not the modem is in use, and the first and second detecting means. When it is detected that the telephone terminal is in an off-hook state and the modem unit is in use, the sound unit is connected to the telephone terminal. The handset of the telephone terminal to perform a telephone communication by the interconnected using a microphone and a speaker,
When it is detected that the telephone terminal is in an off-hook state and the modem unit is not in use, the telephone terminal is connected to the public line network and used for telephone communication by circuit switching. A telephone switching system comprising switching means. 2. The method according to claim 1, wherein the switching unit is configured to switch between the first and second switches.
When the detecting unit detects that the telephone terminal is in the on-hook state and the modem unit is in use, the sound unit is disconnected from the telephone terminal and connected to the sound source unit. 2. The telephone switching system according to claim 1, wherein a telephone communication by said interconnection is performed by using a sound source means for voice input / output. 3. A telephone switching system for switching between telephone communication by interconnection according to a communication network protocol and telephone communication by circuit switching, wherein: a sound unit that inputs and outputs a sound signal used in telephone communication by the interconnection; A wireless communication is performed between a sound source unit that emits a sound signal from a sound unit, collects an external sound, and inputs the sound signal to the sound unit, a mobile phone that can perform normal call transmission and reception, and the mobile phone. Communication means; first detection means for detecting an off-hook state of the mobile phone based on a signal input from the mobile phone via the communication means; and a modem connected to the public network for use. The mobile phone is in an off-hook state by the first and second detection means. When it is detected that the modem unit is in use, the sound unit is connected to the mobile phone via the communication means, and the telephone communication by the interconnection is performed using the handset of the mobile phone as a microphone and a speaker. The mobile phone is in an on-hook state,
And, when it is detected that the modem unit is in use, the sound unit is switched and connected to the sound source means,
A telephone switching system for performing telephone communication by said interconnection using said sound source means for voice input / output; 4. A terminal device provided in a personal computer for performing telephone communication by interconnection by connecting a modem unit to a public line network, comprising: a sound unit for inputting and outputting a sound signal; Sound source means for generating a sound signal and converting external sound into a sound signal and inputting the sound signal to the sound unit; first detecting means for detecting an off-hook state of an externally connected telephone terminal; Second detecting means for detecting whether the telephone terminal is in use by connecting the telephone terminal to the public line network, and the telephone terminal is in an off-hook state by the first and second detecting means, and When it is detected that the telephone is in use, the sound section is connected to the telephone terminal, and the telephone through the interconnection is used by using the handset of the telephone terminal as a microphone and a speaker. To perform the communication,
When it is detected that the telephone terminal is in the off-hook state and the modem unit is not in use, the telephone terminal is switched to the public line network to connect the telephone terminal to a normal line. A terminal device comprising: switching means used for telephone communication by exchange. 5. The modem unit processes a modem signal,
A modem signal processing unit that outputs a line capture control signal when the modem unit is connected to the public line network and is in use; a data access circuit unit that processes a line; the public line network and the telephone terminal 5. The terminal device according to claim 4, further comprising: a line / sound source switching unit for switching between the sound unit and the sound source unit. 6. The line / sound source switching unit connects the data access circuit unit and the public line network, and connects the telephone terminal to the public line network when the line capture control signal is input. A capturing unit, a hooking detection unit that detects an off-hook state of the telephone terminal, a conversion circuit that converts a signal from the telephone terminal into a 2-wire 4-wire connection to the sound unit, and the line capture control signal. The sound section is connected to the conversion circuit when both the hooking signals at the time of detecting the off-hook state are input from the hooking detection section, and the sound is output when only one of the line capture control signal and the hooking signal is input. The terminal device according to claim 4, further comprising a switching circuit that connects a unit to the sound source unit. 7. A terminal device provided in a personal computer for performing telephone communication by interconnection by connecting a modem unit to a public line network, comprising: a sound unit for inputting and outputting a sound signal; Sound source means for generating a sound signal and converting external sound into a sound signal and inputting the sound signal to the sound unit; communication means for wirelessly communicating with a mobile phone; and the communication means from the mobile phone via the communication means. First detecting means for detecting an off-hook state of the mobile phone based on an input signal; second detecting means for connecting the modem unit to the public network to detect whether the mobile phone is in use; When the first and second detection units detect that the mobile phone is in an off-hook state and the modem unit is in use, the mobile phone is connected to the communication unit via the communication unit. A sound unit is connected to the mobile phone, and a telephone communication by the interconnection is performed using a handset of the mobile phone as a microphone and a speaker, the mobile phone is in an on-hook state, and the modem unit is in use. Switching means for switching the sound unit to the sound source means when the presence of the sound source is detected, and using the sound source means for voice input / output to perform telephone communication by the interconnection. apparatus.