JP3631684B2 - Telephone switching system and terminal device used therefor - Google Patents

Description

[0001]
BACKGROUND 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 that can be used for both a personal computer telephone and a normal telephone and a terminal device used therefor.
[0002]
[Prior art]
Conventionally, voice communication of Internet telephones that perform real-time voice communication between personal computers (personal computers) via the Internet is performed by connecting a speaker and a microphone to a sound source device connected to the personal computer and the personal computer. This method is used. However, this method makes it impossible to have a private conversation because the sound is heard from the speaker.
[0003]
Therefore, power is supplied to telephone terminals that have been used on a daily basis, and two-wire / four-wire conversion is performed to separate transmission and reception signals and connect to a sound source device installed in a personal computer. There is known a telephone switching system in which a received voice signal is switched to be output to a speaker output terminal of a sound source device of a personal computer or to a speaker unit of a telephone terminal device according to the state of a hook switch of the device ( JP, 2000-270123, A).
[0004]
Further, in the field of packet network telephone devices that allow voice data to be communicated on a packet network, a telephone can be connected to a public switched telephone network (PSTN) line or a packet network according to the power on / off state of the device. A device that includes a fallback switch connected to any one of these lines and can be optionally selected is also known (Japanese Patent Laid-Open No. 11-355474).
[0005]
[Problems to be solved by the invention]
However, in the method of making an Internet phone call and a normal phone call using the same terminal, the apparatus becomes large-scale, and a telephone terminal used on a daily basis owned by most households is wasted. Further, in the system described in Japanese Patent Laid-Open No. 2000-270123, private conversations can be made, but the telephone terminal can only be used instead of a microphone and a speaker. I can't do it.
[0006]
Furthermore, in the system described in Japanese Patent Application Laid-Open No. 11-355474, the PSTN line and the packet network are switched by turning on / off the power, and the IP telephone can be used when the power is turned on. Therefore, it is effective for a cable modem or the like, but is not effective for a normal modem used in an environment where a constant connection is not possible.
[0007]
The present invention has been made in view of the above points, and an object of the present invention is to provide a telephone switching system that can be used by switching between a personal computer telephone and a normal telephone on the terminal, and a terminal device used therefor.
[0008]
Another object of the present invention is to provide a telephone switching system that can be used for switching between a personal computer telephone and a normal telephone using a normal modem used in an environment in which a constant connection is not possible, and a terminal device used therefor. .
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the telephone switching system of the present invention switches the connection of a normal telephone terminal to the public line network, thereby enabling telephone communication by mutual connection based on a communication network protocol and telephone communication by line switching. A telephone switching system for switching between sound units that input / output sound signals used in interconnected telephone communications, and sound signals from the sound units. Sound from outside is collected and input to the sound unit. Sound source means, first detection means for detecting the off-hook state of the telephone terminal, second detection means for detecting whether the modem unit is connected to the public line network, and first and second Connects the sound part to the telephone terminal when it is detected by the detection means that the telephone terminal is off-hook and the modem part is in use. When the telephone terminal is off-hook and the modem unit is not in use, the telephone terminal is used when the telephone terminal is in an off-hook state and the modem is not in use. And switching means used for telephone communication by line switching by connecting the machine to a public line network.
[0010]
In this 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 to the microphone and When it is detected that the telephone terminal is off-hook and the modem unit is not in use, the telephone terminal is connected to the public line network when the telephone terminal is used as a speaker to perform telephone communication by interconnection. Normal use of the terminal is possible.
[0011]
In order to achieve the above object, according to the present invention, the switching means is detected by the first and second detection means that the telephone terminal is in the on-hook state and the modem unit is in use. In this case, the sound unit 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.
[0012]
In order to achieve the above object, the present invention provides a telephone switching system for switching between telephone communication based on interconnection using a communication network protocol and telephone communication based on circuit switching. Between a sound unit for input / output, sound source means for generating a sound signal from the sound unit, collecting sound from the outside and inputting it to the sound unit, a mobile phone capable of making and receiving calls, and a mobile phone The communication means for performing wireless communication with the mobile phone, the first detection means for detecting the off-hook state of the mobile phone based on the signal input from the mobile phone via the communication means, and the modem unit connected to the public line network The mobile phone is in an off-hook state and the modem unit is in use by the second detection means for detecting whether the mobile phone is in the middle and the first and second detection means When it is detected that the sound unit is connected to the mobile phone through the communication means, the mobile phone's handset is used as a microphone and a speaker to perform telephone communication by interconnection, and the mobile phone is in an on-hook state. In addition, when it is detected that the modem unit is in use, the sound unit is switched and connected to the sound source means, and the sound source means is used for voice input / output to perform telephone communication by interconnection.
[0013]
In the present invention, since the sound unit is connected to the mobile phone via the communication means when it is detected that the mobile phone is in the off-hook state and the modem unit is in use, the handset of the mobile phone is It can be used for a microphone and a speaker for telephone communication by interconnection such as the Internet.
[0014]
In order to achieve the above object, a terminal device according to the present invention is a terminal device provided in a personal computer that connects a modem unit to a public line network and performs telephone communication by interconnection. Sound part to input / output, sound signal from sound part, sound source means to convert external sound into sound signal and input to sound part, and detect off-hook state of externally connected phone terminal The telephone terminal is in an off-hook state by the first detection means, the second detection means for detecting whether the modem unit is connected to the public line network, and the first and second detection means. And when it is detected that the modem unit is in use, the sound unit is connected to the telephone terminal, and the telephone terminal's handset is used as a microphone and a speaker to perform telephone communication by interconnection. If it is detected that the telephone terminal is off-hook and the modem is not in use, switch the telephone terminal to the public line network and connect the telephone terminal to the normal line exchange. And a switching unit used for telephone communication.
[0015]
The present invention uses a telephone handset as a microphone and a speaker by connecting a sound part to a telephone terminal when it is detected that the telephone terminal is in an off-hook state and the modem part is in use. If the telephone terminal is off-hook and the modem is not in use, the telephone terminal is switched to the public line network and connected to the telephone terminal. Is used for telephone communication by normal circuit switching.
[0016]
In order to achieve the above object, a terminal device according to the present invention is a terminal device provided in a personal computer that connects a modem unit to a public line network and performs telephone communication by interconnection. A sound unit that inputs and outputs; a sound source unit that generates a sound signal from the sound unit, converts sound from the outside into a sound signal and inputs the sound signal; and a communication unit that wirelessly communicates with the mobile phone; First detection means for detecting the off-hook state of the mobile phone based on a signal input from the mobile phone via the communication means, and second for detecting whether the modem unit is connected to the public line network. When the mobile phone is detected to be in an off-hook state and the modem unit is in use by the detection means and the first and second detection means, the sound part is transmitted via the communication means. When it is detected that the mobile phone is on-hook and the modem unit is in use, the mobile phone is connected to the mobile phone and the telephone handset of the mobile phone is used as a microphone and speaker to perform interconnection communication. The sound unit is switched and connected to the sound source means, and the sound source means is used for voice input and output, and switching means for performing telephone communication by interconnection is used.
[0017]
In the present invention, since the sound unit is connected to the mobile phone via the communication means when it is detected that the mobile phone is in the off-hook state and the modem unit is in use, the handset of the mobile phone is It can be used as a microphone and a speaker to perform telephone communication by interconnection.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of an embodiment of a telephone switching system and a terminal device used therefor according to the present invention. In FIG. 1, a terminal device 10 is provided in a personal computer 20 and is connected to an I / O bus 21 in the personal computer 20 for performing data input / output processing with a host device of the personal computer 20 and a sound. Part 12.
[0019]
The modem unit 11 includes a modem signal processing unit 13 that processes modem signals, a data access circuit unit (DAA) 14 that performs line processing, a line / sound source switching unit 15 that switches between line and sound, Consists of. The sound unit 12 includes a sound signal processing unit 16 that is connected to the I / O bus 21 and performs sound processing, and a sound input / output unit 17 that inputs and outputs sound sources.
[0020]
Outside the terminal device 10 and the personal computer 20, a telephone terminal 32, which is a normal subscriber phone that is generally used, a microphone (abbreviated as a microphone) 33, and a speaker 34 are connected. The terminal device 10 can be connected to the public network 31. The public line network 31 includes both an interconnection network such as the Internet and a line switching network such as a telephone network and ISDN.
[0021]
Next, the schematic operation of one embodiment of the telephone switching system of the present invention will be described with reference to FIG. When the operator uses the modem unit 11 of the personal computer 20 to communicate with the outside using the public line network 31 such as the Internet, a line capture control signal is output from the modem signal processing unit 13 to The sound source switching unit 15 is supplied.
[0022]
When the telephone terminal 32 is off-hooked when the modem is used (when the handset is raised), 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 the telephone used everyday. The handset of the terminal 32 is used as a microphone / speaker, and Internet telephone is possible.
[0023]
When using the modem, when the telephone terminal 32 is in the on-hook state, the sound input / output unit 17, the microphone 33, and the speaker 34 are connected under the control of the line / sound source switching unit 15. When the modem is not used, the line capture control signal is not input to the line / sound source switching unit 15. If the telephone terminal 32 enters an off-hook state at this time, the line / sound source switching unit 15 The machine 32 can be connected to the public network 31 and the telephone terminal 32 can be used as a normal telephone.
[0024]
Next, the configuration and operation of the line / sound source switching unit 15, which is the main part of the present invention, will be described in more detail. FIG. 2 shows a block of an embodiment of the line / sound source switching unit 15 of the main part of the present invention together with peripheral circuits. In the figure, the same components as those in FIG.
[0025]
In FIG. 2, the line / sound source switching unit 15 includes a line capture unit 41 that performs connection or disconnection with the telephone terminal 32 depending on whether a line capture control signal is input from the modem signal processing unit, and a telephone terminal. A hooking detection unit 42 that detects that the machine 32 is off-hook, an AND circuit 43 that is in a gate “open” state when a hooking signal is input from the hooking detection unit 42, and passes a line capture control signal; A circuit that switches and connects the input and output of the sound input / output unit 17 to the (2) side two-wire four-wire exchange hybrid circuit 45 or the (3) side microphone 33 and speaker 34 according to the signal from the circuit 43 Level conversion for converting the level of the audio signal to a level that can be received by the sound switching circuit 44, the two-wire four-wire exchange hybrid circuit 45, and the telephone terminal 32 It is more configuration and road 46.
[0026]
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 a line, a line capture control signal is output from the modem signal processing unit 13 under the control of 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 disconnects the (1) side, that is, the telephone terminal 32 and the sound unit 12 side. In this state, the modem unit 11 is capturing the line, that is, the personal computer is using the public line network 31 via the modem unit 11, and the operator communicates with the outside by connecting to the Internet or the like. It is in the state of going.
[0027]
On the other hand, when the modem unit 11 is not using a line, the line capture control signal is not output from the modem signal processing unit 13, and the line capture unit 41 is connected to the (1) side, that is, the telephone terminal 32 side and the sound unit. 12 is in an initial state where it is connected. Therefore, whether or not the modem unit 11 is used can be determined by whether or not the line capture control signal is output from the modem signal processing unit 13.
[0028]
If the user of the telephone terminal 32 raises the handset, that is, assumes the off-hook state (step 101 in FIG. 3), the off-hook state is detected by the hooking detection unit 42 and the hooking signal is detected. Is supplied to the AND circuit 43. At this time, as described above, it is determined whether or not the modem unit 11 is used depending on whether or not the line capture control signal is output from the modem signal processing unit 13 (step 102 in FIG. 3). When in use, the line capture unit 41 is in a state where a line capture control signal is input and the telephone terminal 32 and the sound unit 12 are disconnected, and the AND circuit 43 is in the gate “open” state.
[0029]
Thus, when the telephone unit 32 is in 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, and the line / sound switching circuit 44 Switching from (3) side to (2) side connects the sound input / output unit 17 to the two-wire / four-wire conversion hybrid circuit 45 (step 103 in FIG. 3).
[0030]
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-line / four-line conversion hybrid circuit 45, and the level that can be received by the telephone terminal 32 by the level conversion circuit 46. And is input / output to / from the handset of the telephone terminal 32. As a result, when the personal computer uses the public line network 31 via the modem unit 11 and the telephone terminal 32 is off-hook while the operator is connected to the Internet and communicating with the outside, the telephone terminal It functions as a microphone and a speaker of the handset of the machine 32 (step 104 in FIG. 3). Therefore, at this time, the normal telephone terminal 32 can be used as an Internet telephone.
[0031]
On the other hand, when it is determined in step 102 that the modem unit 11 is not being used when the telephone terminal 32 is off-hooked, a line capture control signal is not output from the modem signal processing unit 13, and the line capture unit 41 1, that is, in an initial state where the telephone terminal 32 side is connected, and the AND circuit 43 is in a gate “closed” state.
[0032]
As a result, when the telephone unit 32 is set to the off-hook state, if the modem unit 11 is not used, the hooking signal is not supplied to the line / sound switching circuit 44, and the line / sound switching circuit 44 is Since 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 (FIG. 3). Step 105).
[0033]
When the modem unit 11 is in use but the telephone terminal 32 is not off-hooked, as described above, the hooking signal is not supplied to the line / sound switching circuit 44, and the line / sound switching circuit 44 is set to (2). Therefore, the sound signal output from the sound input / output unit 17 is supplied to the speaker 34 through the line / sound switching circuit 44 to be sounded, and the sound collected by the microphone 33 is recorded. Is converted into a sound signal and then input to the sound input / output unit 17 through the line / sound switching circuit 44.
[0034]
Thus, in this embodiment, when the operator is connected to the Internet via the public network 31 using the modem unit 11 of the personal computer, the telephone terminal 32 used on a daily basis is connected to the Internet telephone. When the Internet is not used, it can be automatically switched and used as a normal telephone. Further, in this embodiment, the telephone unit 32 or the microphone 33 and the speaker 34 are used as a trigger based on whether or not the modem unit 11 is used. You can select and use Internet phone and regular phone even with a personal computer using.
[0035]
Next, another embodiment of the present invention will be described. FIG. 4 shows a block diagram of another embodiment of a telephone switching system according to the present invention and a terminal device used therefor. In the figure, the same components as those in FIG. In FIG. 4, the terminal device 50 is provided in a personal computer and includes a modem unit 51 and a sound unit 12 connected to the I / O bus 21 in the personal computer.
[0036]
The modem unit 51 includes a modem signal processing unit 13 that processes modem signals, a data access circuit unit (DAA) 14 that performs line processing, a line / sound source switching unit 15 that switches between line and sound, , An A / D conversion unit 53 and a radio unit 59.
[0037]
The terminal device 50 is configured such that the wireless unit 54 can be connected to a normal mobile phone 55. The mobile phone 55 is a mobile phone compatible with a simple mobile phone (PHS) or Bluetooth, and wirelessly communicates with the wireless unit 54, and a signal received by the wireless unit 54 is digitally converted by the A / D converter 53. It is converted into a signal and supplied to the line / sound source switching unit 52. The A / D conversion unit 53 and the wireless unit 54 convert to a known wireless output such as PIAFS or Bluetooth.
[0038]
In this embodiment, the line / sound source switching unit 52 does not have the line capturing unit 41 as compared with the configuration of the line / sound source switching unit 15 shown in FIG. When a line capture control signal indicating that the signal is in the middle is input 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 A / D converted. Connect to the unit 53.
[0039]
As a result, the sound input from the mobile phone 55 is converted into a sound signal by the microphone of the mobile phone 55, wirelessly transmitted to the wireless unit 54, and further via the A / D converter 53 and the line / sound source switching unit 52. To the sound unit 12. Also, 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, converted into a digital signal here, and then wirelessly transmitted from the wireless unit 54 to the mobile phone 55. The sound is generated from the speaker of the mobile phone 55.
[0040]
Note that the line / sound source switching unit 52 receives a signal indicating an off-hook state from the cellular phone 55 even if the line capture control signal indicating that the modem is in use is input from the modem signal processing unit 13. When there is no input through the / D conversion unit 53, the sound unit 12 is connected to the microphone 33 and the speaker. In addition, when performing normal telephone communication, the mobile phone 55 performs communication according to a protocol similar to the conventional one via a radio base station (not shown).
[0041]
As described above, according to this embodiment, when the modem unit 51 is used to make a personal computer telephone such as an Internet telephone (that is, telephone communication by mutual connection using a communication network protocol), the mobile phone 55 is connected to a cordless telephone. It can be used like a handset, and as a result, you can make a PC phone call away from the PC.
[0042]
The present invention is not limited to the above-described embodiment. For example, a dial (pulse tone) signal transmitted from a telephone terminal by an interface telephone application in combination with an interface telephone application built in a personal computer. , And automatically making an Internet telephone call, it is possible to realize an Internet telephone by operating a normal telephone terminal when connected to the Internet.
[0043]
【The invention's effect】
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 telephone is connected. If the handset of the terminal is used as a microphone and a speaker to perform telephone communication by interconnection, and the telephone terminal is detected to be in an off-hook state and the modem unit is not in use, the telephone terminal is Since the telephone terminal can be used normally by connecting to the public line network, no special operation is required, and the telephone terminal can be used for telephone communication by interconnection such as Internet telephone with the same feeling as the telephone used in daily life. Alternatively, a mobile phone can be used.
[0044]
Further, according to the present invention, when it is detected that the mobile phone is in the off-hook state and the modem unit is in use, the sound unit is connected to the mobile phone via the communication means, thereby Since the handset is used as a microphone and speaker to perform telephone communication by mutual connection, the mobile telephone is used as a cordless telephone cordless handset, away from the front of a personal computer, and by telephone connection by Internet telephone or other interconnection. Can do.
[0045]
Furthermore, according to the present invention, a telephone terminal or a microphone and a speaker are used as a trigger based on whether or not the modem unit is used, and a normal modem unit used in an environment where continuous connection is not possible is used. Even with a personal computer, it is possible to select and use a telephone for telephone communication and an ordinary telephone by interconnection such as Internet telephone.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of the present invention.
2 is a block diagram of an embodiment of a line / sound source switching unit as a main part of FIG. 1; FIG.
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 devices 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 (personal computer)
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 phone

Claims (7)

A telephone switching system that switches between telephone communication by interconnection using a communication network protocol and telephone communication by circuit switching by switching the connection of a normal telephone terminal to the public line network,
A sound unit for inputting and outputting a sound signal used in telephone communication by the interconnection;
Sound source means for generating a sound signal from the sound unit, collecting sound from the outside and inputting it to the sound unit;
First detecting means for detecting an off-hook state of the telephone terminal;
Second detecting means for detecting whether the modem unit is connected to the public line network and is in use;
When the first and second detection means detect 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 When it is detected that the telephone terminal is in an off-hook state and the modem unit is not in use, using the handset of the telephone terminal as a microphone and a speaker to perform telephone communication by the interconnection, A telephone switching system comprising switching means for connecting the telephone terminal to the public line network and using it for telephone communication by line switching. The switching means detects the sound unit when the first and second detection means detect that the telephone terminal is in an on-hook state and the modem is in use. 2. The telephone switching system according to claim 1, wherein the telephone switching system is connected to the sound source means by disconnecting from the sound source means, and the sound communication means is used for voice input / output to perform telephone communication by the interconnection. A telephone switching system that switches between telephone communication based on interconnection using a communication network protocol and telephone communication based on circuit switching,
A sound unit for inputting and outputting a sound signal used in telephone communication by the interconnection;
Sound source means for generating a sound signal from the sound unit, collecting sound from the outside and inputting it to the sound unit;
A normal mobile phone that can make and receive calls,
A communication means for performing wireless communication with the mobile phone;
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;
Second detecting means for detecting whether the modem unit is connected to the public line network and is in use;
When the first and second detection means detect that the cellular phone is in an off-hook state and the modem unit is in use, the sound unit is connected to the cellular phone via the communication unit. Then, using the handset of the mobile phone as a microphone and a speaker to perform telephone communication by the interconnection, when it is detected that the mobile phone is in an on-hook state and the modem unit is in use, A telephone switching system, wherein the sound unit is switched and connected to the sound source means, and the sound communication means is used for voice input / output to perform telephone communication by the interconnection. 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 sound signals;
Sound source means for generating a sound signal from the sound unit, and external sound is converted into a sound signal and input 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 modem unit is connected to the public line network and is in use;
When the first and second detection means detect 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 When it is detected that the telephone terminal is in an off-hook state and the modem unit is not in use, using the handset of the telephone terminal as a microphone and a speaker to perform telephone communication by the interconnection, A terminal device comprising switching means for switching and connecting the telephone terminal to the public line network and using the telephone terminal for telephone communication by normal line switching. The modem unit processes a modem signal, and when the modem unit is connected to the public line network and outputs a line capture control signal when in use, a data access circuit unit for processing the line 5. The terminal device according to claim 4, further comprising: a line / sound source switching unit for switching between the public line network and the telephone terminal and switching between the sound unit and the sound source means. The line / sound source switching unit connects the data access circuit unit and the public line network, and at the time of inputting the line capture control signal, a line capture unit that connects the telephone terminal to the public line network; From a hooking detection unit that detects an off-hook state of a telephone terminal, a conversion circuit that converts a signal from the telephone terminal into a two-wire four-line connection to the sound unit, a line capture control signal, and the hooking detection unit The sound unit is connected to the conversion circuit when both of the hooking signals at the time of detecting the off-hook state are input, and when only one of the line capture control signal and the hooking signal is input, the sound unit is connected to the sound source means. 6. The terminal device according to claim 4, further comprising a switching circuit connected to the terminal. 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 sound signals;
Sound source means for generating a sound signal from the sound unit, and external sound is converted into a sound signal and input to the sound unit;
A communication means for wirelessly communicating with a mobile phone;
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;
Second detecting means for detecting whether the modem unit is connected to the public line network and is in use;
When the first and second detection means detect that the cellular phone is in an off-hook state and the modem unit is in use, the sound unit is connected to the cellular phone via the communication unit. When it is detected that the mobile phone is on-hook and the modem unit is in use by connecting and making the telephone communication by the interconnection using the handset of the mobile phone as a microphone and a speaker And a switching means for switching and connecting the sound unit to the sound source means and using the sound source means for voice input / output to perform telephone communication by the interconnection.

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