JPH1051837A - Mobile data communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain smooth transition to data communication by giving an instruction it that a data communication terminator of a communication opposite party is started in a transmission mode when data communication is transited by a changeover request signal from voice communication to data communication sent from a mobile communication subscriber terminal equipment. SOLUTION: Suppose that voice communication is conducted between a mobile telephone set 101 and a telephone set 124, it is switched into data communication. When the mobile telephone set 101 outputs a switching request signal for data communication, then a switching request signal detector 112 in a mobile telephone exchange 107 detects it. A mobile telephone exchange controller 114 allows a sound signal transmitter 109 to send a sound signal to a communication opposite party so as to instruct transition to data communication in the transmission mode. When the communication opposite party enters a command accordingly, the opposite party is started in the transmission mode to realize the transition to the data communication. When the transition is finished, the transmission of the sound signal is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile data communication system using a digital exchange, and more particularly to a mobile data communication system in which voice communication is manually switched from data communication.

[0002]

2. Description of the Related Art In a data communication system in which data is exchanged between stations via an analog line using a digital exchange, a modem has been conventionally arranged on the local station side, and a carrier sound from the modem of the opposite station is transmitted to the local station. The modem on the side detects it. In such a communication system, when the opposite modem or data terminal device is in a busy state, the busy modem cannot detect the busy tone.
Therefore, in such a case, the operator waits until the predetermined timer times out and the line is disconnected. Therefore, Japanese Patent Application Laid-Open No. 62-7296 proposes a technique that allows the operator to listen to the busy tone.

FIG. 6 shows an example of the proposed mobile data communication system. This system includes a data terminal device 11 in which input means such as a keyboard is arranged. The data terminal device 11 is connected to a time division switch 13 via a data terminal interface device (IF) 12. The time-division switch 13 is connected to a central control unit (CPU) 14 for controlling the time-division switch 13 and a modem 1 via a modem interface (IF) trunk 15.
6 and an analog line 18 via an analog line trunk 17.

In the proposed mobile data communication system,
When a transmission request is made by a keyboard operation of the data terminal device 11, the data terminal interface device 12 detects the request and notifies the central control device 14. The central control unit 14 controls a data channel 19 coming from the data terminal device 11 via the data terminal interface device 12,
The digital / analog signal is converted by the modem 16.
For this purpose, the data terminal device 11 is passed through the modem interface trunk 15 and
Connect to 7. In addition, the data terminal interface device 1
The two voice channels 21 are directly connected only in the direction from the analog line trunk 17.

In this communication system, a carrier sound from a not-shown modem of the opposite station is detected by the modem 16 of the own station. Then, the notification is sent to the central controller 14 via the modem interface trunk 15. At this time, a ringing tone of the game and a carrier tone from the modem can be heard from the speaker 22 of the data terminal interface device 12.

When the carrier sound is detected, data exchange starts. The central controller 14 operates the time-division switch 13 based on the notification of the detection of the carrier sound to disconnect the switch related to the audio channel 21 or stop the input of the speaker 22 in the data terminal interface device 12 and During communication, the acoustic signal
2 is prevented from being output.

When all the modems (not shown) of the game are in a busy state, or when a data terminal device (not shown) to be connected is in a busy state, a busy sound is returned from the game. This busy tone is output from the speaker 22 via the above-mentioned voice channel. Therefore, the operator can hear this busy tone and cut off the communication at his own discretion. In the case where a normal telephone is called by mistake, the voice of the other party is heard from the speaker 22, so that it is possible to judge at this point that the connection is incorrect.

[0008]

When voice communication is being performed in a mobile data communication system, there is a case where the mobile communication system is manually switched to data communication halfway. In such a case, if the originating side and the terminating side do not set up properly for transitioning to data communication, the ambiguity between the two modems will cause the physical connection sequence between the modems to not end normally and the data communication to be terminated. Can not start. That is, in a digital mobile data communication system, there are restrictions on the operation mode of the data communication terminating device on the transmitting side and the operation mode of the data communication device on the other end of communication.

For example, in a case where mobile communication subscribers shift from voice communication to data communication, if one of the mobile communication subscribers starts the data communication terminating device first in the receiving mode, the other mobile communication subscriber starts the other. A mobile communication subscriber can transition to data communication only if the data communication termination device is started in the transmission mode. Also, when the mobile communication subscriber and the general network side switch from voice communication to data communication, when the data communication terminating device of the mobile telephone is started in the receiving mode, the data communication on the general network side is performed. It is only possible to start the terminating device in the transmission mode in the operation mode, or to start the operation in the reverse operation mode, and to shift to the data communication only in either case.

However, in spite of these restrictions, the other party of the communication starts its own data communication terminating device in the transmission mode after one of them sets the data communication terminating device in the receiving mode first. There is no means to determine whether to start in incoming mode. For this reason, there was a possibility that the transition from voice communication to data communication could not be performed smoothly.

Therefore, an object of the present invention is to provide a data communication terminating device for transmitting data to a data communication terminating device when a transition is made to data communication by a switching request signal from voice communication to data communication transmitted from a mobile communication subscriber terminal. It is an object of the present invention to provide a digital mobile data communication system which can be instructed to start with a mobile communication system.

Another object of the present invention is to provide a mobile communication system in which a data communication terminating device of a communication partner is instructed to start in a transmission mode using an acoustic signal as described in the prior art. A communication system is provided.

[0013]

According to the first aspect of the present invention, there are provided (a) a digital mobile communication subscriber terminal;
Switch request signal detecting means for detecting when the digital mobile communication subscriber terminal outputs a switch request signal for switching from voice communication to data communication; and when the switch request signal detecting means detects the switch request signal. The mobile data communication system includes a mobile telephone exchange having an audio signal transmitting means for transmitting an audio signal for urging a communication partner to shift from voice communication to data communication in the transmission mode.

That is, according to the first aspect of the present invention, when the digital mobile communication subscriber terminal switches from voice communication to data communication, this is detected by the switching request signal detecting means on the mobile telephone exchange side, and the other party of the communication is notified. By transmitting an acoustic signal to prompt the transition from voice communication to data communication in the transmission mode, the other party of the communication can set the transmission mode, thereby facilitating the transition from voice communication to data communication. .

According to the second aspect of the present invention, (a) the digital mobile communication subscriber terminal and (b) the digital mobile communication subscriber terminal output a switching request signal for switching voice communication to data communication. When the switching request signal detecting means detects the switching request signal, the switching request signal detecting means detects the switching request signal when the switching request signal detecting means detects the switching request signal. A mobile data communication system is provided with an audio signal transmitting means for transmitting and a mobile telephone exchange provided with a protocol conversion means for converting between a data transmission protocol in a wireless section and a data transmission protocol in a wired section.

That is, according to the second aspect of the present invention, when the digital mobile communication subscriber terminal switches from voice communication to data communication, this is detected by the switching request signal detection means on the mobile telephone exchange side, and the other party of the communication is notified. By transmitting an acoustic signal that prompts a transition from voice communication to data communication in the transmission mode, the communication partner can be set to the transmission mode, and the protocol conversion means and the data transmission protocol of the wireless section and the wired section are transmitted. In order to improve the transmission quality, the data transmission protocols are mutually converted, error control is independently performed in a section where the transmission quality is poor.

According to the third aspect of the present invention, (a) the digital mobile communication subscriber terminal and (b) the digital mobile communication subscriber terminal output a switching request signal for switching voice communication to data communication. When the switching request signal detecting means detects the switching request signal, the switching request signal detecting means detects the switching request signal when the switching request signal detecting means detects the switching request signal. Acoustic signal transmitting means for transmitting, protocol converting means for mutually converting between a wireless section data transmission protocol and a wired section data transmission protocol, and transition detecting means for detecting that a communication partner has shifted from voice communication to data communication. When the transition detection means detects that the transition from voice communication to data communication has been made, the transmission of the acoustic signal by the acoustic signal transmission means is performed. Sealed to be provided to the mobile data communications system and a mobile telephone exchange and a sound signal sending means stopping means.

That is, when the digital mobile communication subscriber terminal switches from voice communication to data communication, this is detected by the switching request signal detecting means on the mobile telephone exchange side, and the other party of the communication is notified to the other party of the communication. By transmitting an acoustic signal that prompts a transition from voice communication to data communication in the transmission mode, the communication partner can be set to the transmission mode, and the protocol conversion means and the data transmission protocol of the wireless section and the wired section are transmitted. In order to improve the transmission quality, the data transmission protocols are mutually converted, error control is independently performed in a section where the transmission quality is poor. Also, since the transition detecting means detects that the communication partner has shifted from voice communication to data communication, and at this point, the sound signal sending means stopping means stops sending the sound signal by the sound signal sending means, The sound signal does not adversely affect data communication when it starts.

According to a fourth aspect of the present invention, in the mobile data communication system of the first to third aspects, the communication partner is a digital mobile communication subscriber terminal or a subscriber terminal of a general public telephone network. Clarify.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows the overall configuration of a mobile data communication system according to one embodiment of the present invention. In this communication system, a mobile telephone (MS) 101
Is a data terminal device (PCa) 1 via a mobile data communication adapter (ADP) 102 and a data communication terminating device (MDa) 103 used for mobile data communication.
04. The mobile telephone 101 includes a radio line 105 and a radio base station / base station control station (BSS) 106.
Is connected to a time division switch (TDSW) 108 in a mobile telephone exchange (MSC) 107. The time-division switch 108 includes an acoustic signal transmission device (TONE) 109, a protocol conversion device (IWF) 111, and a switching request signal detection device (D) in the mobile telephone exchange 107.
ET) 112 and a mobile telephone exchange controller (CC) 114 via a bus 113. Also, a general public switched telephone network (PSTN) 121 and a data terminal device (MDb) 1 outside the mobile telephone exchange 107.
22, a data terminal device (PCb) 123 as a communication partner of the mobile telephone 101 and the telephone 12
4 is connected.

The mobile telephone exchange control unit 114 in the mobile telephone exchange 107 controls the time division switch 108 according to the result of the call processing, and controls the radio base station / base station control station 10.
6, audio signal transmitting device 109, general public network 121,
A communication channel between the protocol conversion device 111 and the switching request signal detection device 112 is formed. The acoustic signal transmission device 109, the protocol conversion device 111, and the switching request signal detection device 112 are controlled by a mobile telephone exchange control device 114 via a bus 113.

Next, specific configurations of the audio signal transmitting device 109, the switching request signal detecting device 112, and the protocol converting device 111 will be described in order.

FIG. 2 shows a specific configuration of the audio signal transmitting device. The audio signal transmission device 109 includes an audio signal generation circuit (AUD) 13 connected to the bus 113.
1 is provided. The audio signal 132 created by the audio signal generation circuit 131 is converted to a PCM encoding circuit (COD) 13
3 and converted from an analog signal to a digital signal. The converted audio signal 134 is input to a time-division multiplexing circuit (M
UX) 135 as a sound signal 136 in the mobile telephone exchange 107 shown in FIG.
Sent to

An interface circuit (INF) 137 connected to the bus 113 in FIG. 2 is connected to the mobile telephone exchange control unit 114 in the mobile telephone exchange 107 shown in FIG. It is supposed to do. The sound signal generation circuit 131 and the interface circuit 137 are connected to an arithmetic processing circuit (CPU) via the bus 113.
138, a ROM (Read Only Memory) 139 and a RAM (Random Access Memory) 140, and are controlled by a program stored in the ROM 139.

FIG. 3 shows a specific configuration of the switching request signal detecting device. Switching request signal detection device 112
Includes a time division separation circuit (DMUX) 141.
A switching request signal for switching from voice communication to data communication is transmitted from the mobile telephone 101 shown in FIG. 1 onto a control channel of the radio line 105, and transmitted from the radio base station / base station control station 106 and the mobile telephone exchange 107. Time division switch 108
Is input to the time division separation circuit 141 of the switching request signal detection device 112 via The time-division separation circuit 141 separates the switching request signal 143 from the input signal 142, and inputs this to the signal detection circuit (RX) 144 to detect the switching request.

This detection result is transmitted to the interface circuit 13
7 to the mobile telephone exchange control unit 114 in the mobile telephone exchange 107. The signal detection circuit 144 and the interface circuit 137 are connected to the arithmetic processing circuit 138, the ROM 139, and the RAM 140 via the bus 113.
And is controlled by a program stored in the ROM 139.

FIG. 4 shows a specific configuration of the protocol conversion device. Protocol converter 111
Are a first and a second time division demultiplexer (DMUX) 15
1, 152, and first and second time division multiplexing circuits (MUs).
X) 153 and 154 are provided. Communication data 156 is input to the first time-division separation circuit 151 from the time-division switch 108 shown in FIG. The communication data 156 is transmitted from the data terminal device 123 which is the data communication partner of the mobile telephone 101 shown in FIG.
The data is sent via the data terminal device 122, the general public network 121, and the time division switch 108 in the mobile telephone exchange 107. First time division separation circuit 151
Is separated by a PCM decoding circuit (DEC) 158, and the communication data 159 is converted into a modem signal modulation / demodulation circuit (MODEM) 16.
1 and received.

On the other hand, communication data 162 output from the modem signal modulation / demodulation circuit 161 is transmitted to a PCM encoding circuit (CO
D) 163, and the encoded communication data 164 is sent out as communication data 165 via the first time-division multiplexing circuit 153. This communication data 165
Is transmitted to the general public network 121 via the time-division switch 108 in the mobile telephone exchange 107 shown in FIG. 1 and transmitted therefrom to the data terminal device 123 via the data terminal device 122 for reception. Is done.

Another communication data 171 is also input to the second time-division separation circuit 152. The communication data 171 is transmitted from the data terminal device 104 shown in FIG. 1 to the mobile telephone 101 via the data communication termination device 103 and the mobile data communication adapter 102. From there, the data is input to the second time-division demultiplexing circuit 152 as communication data 171 via the radio base station / base station control station 106 and the time-division switch 108 in the mobile telephone exchange 107 via the radio line 105. become. The communication data 172 separated by the second time-division separation circuit 152 is input to the radio protocol termination circuit 173 and received.

On the other hand, the communication data 174 output from the wireless protocol terminating circuit 173 is input to the second time division multiplexing circuit 154, and the multiplexed communication data 175 is stored in the mobile telephone exchange 107 shown in FIG. Time-division switch 1
08. And the radio base station / base station control station 10
6 and transmitted on the communication channel of the wireless line 105,
Mobile phone 101, mobile data communication adapter 10
2 and the data terminal 104 via the data communication terminating device 103.

The modem signal modulation / demodulation circuit 161, the radio protocol termination circuit 173, and the interface circuit 137
Is connected to the arithmetic processing circuit 138 and the ROM 1 via the bus 113.
39 and the RAM 140, and
9 is controlled by a program stored in the memory 9.

FIG. 5 shows the operation of the mobile data communication system configured as described above. It is assumed that the mobile telephone 101 in FIG. 1 and the telephone 124 of the general public telephone network 121 (both shown in FIG. 1) are performing voice communication. At a certain point in time, it is assumed that the subscriber of the mobile telephone 101 has transmitted a "switch request signal" (201) from voice communication to data communication. Specifically, when the subscriber is the mobile telephone 10
The user depresses an operation keypad (not shown) and inputs a predetermined key code. As an example, it is assumed that a key code “F123” is input from the operation keypad. Then, the mobile phone 101 transmits “DATA-RE” as a switching request signal on the control channel of the wireless line 105.
Q ".

The control channel relating to the mobile telephone 101 is connected to the input channel of the time division switch 108 in the mobile telephone exchange 107 via the radio base station / base station control station 106. The input channel and the output channel to the switching request signal detecting device 112 are connected via the time division switch 108 under the control of the mobile telephone exchange control device 114. Therefore, the above-mentioned "switching request signal" is received and detected by the switching request signal detecting device 110, and is used as a "start request signal" (202) for starting the audio signal transmitting device 109 and the protocol converting device 111. The control unit 114 is notified.

The "activation request signal" includes the wireless channel number of the mobile telephone 101 which has requested the switching. The mobile telephone exchange control device 114 that has received the "start request signal" can refer to the call processing data to know the output channel number of the time division switch 108 associated with the communication partner of the mobile telephone 101. . Therefore, the mobile telephone exchange control device 11
4 activates the audio signal transmission device 109 and controls the time division switch 108. When the audio signal (206) is input from the audio signal transmission device 109, the time division switch 1
It is possible to connect a communication channel between the input channel 08 and the output channel related to the communication partner. This allows the telephone signal to be heard by the telephone 124.

In this embodiment, the sound signal is a voice message, for example, "Please input ATD from the data terminal." Here, "AT
"D" is one of the AT commands and is a character string for starting the modem in the calling mode.

At the same time when the transmission of the acoustic signal is completed, the acoustic signal transmitting device 109 controls the mobile telephone exchange control device 114.
And the time division switch 108 is controlled. Then, the connection between the input channel of the time division switch 108 to which the audio signal is input from the audio signal transmitting device 109 and the communication channel of the output channel related to the communication partner is released.
Next, the general public network 12 of the protocol converter 111 is used.
The one-way input / output channel is connected to the input / output channel related to the communication partner of the mobile telephone 101, and the radio base station / base station control station 10 of the protocol converter 111 is connected.
The input / output channels in six directions and the input / output channels related to the communication channel of the mobile telephone 101 are connected.

The subscriber of the telephone set 124 which has received the audio signal can use the data terminal device 123 as instructed by the message.
Sends a command “ATD” 207 to the data terminal device 122.
Is sent. As a result, the data terminal device 122 starts operating in the incoming call mode.

Immediately after receiving the "start signal" (203), the protocol converter 111 sets its own communication mode as the transmission mode, and monitors the modem carrier signal "ANS" sent from the communication partner for 10 seconds. If the modem carrier signal "ANS" has not been received from the other party even after 10 seconds have elapsed, the operation mode of the other party is automatically set to the receiving mode, an answer tone (208) is transmitted, and the modem carrier signal "ANS" is transmitted. (209) is started. Here, for the first time, the modem carrier “ORG” (origination, originating) from the data terminal device 122 (21)
0) starts the physical connection protocol. "ORG" is an analog signal output on two lines (the telephone line side) of the modem, and indicates that the modem is operating in the calling mode.

Upon receiving the activation request signal, the mobile telephone exchange controller 114 controls the idle protocol converter 11
A start signal is sent to the wireless communication device 1 so that a mutual conversion between the data transmission protocol in the wireless section and the data transmission protocol in the wired section is performed. The protocol conversion apparatus 111 that has been normally started up returns the fact to the mobile telephone exchange control unit 114 as a “startup completion signal” 204.

On the other hand, the mobile telephone 101 that has received the “start-up completion signal” switches its internal circuit (not shown) for data communication, and the mobile data communication adapter 1.
02, a "switch signal" (205) is transmitted. As a result, the mobile data communication adapter 102 is activated to start the wireless protocol in the wireless section and to start the physical connection protocol based on the data terminal device 104 and the modem carrier signal “ORG”.

The mobile communication subscriber is the mobile telephone 101
Sends a command from the data terminal device 104 to the data communication terminating device 103 so that the data communication terminating device 103 immediately operates in the incoming call mode. Alternatively, by transmitting a command from the data terminal device 104 to the data communication terminating device 103 during a voice call, the mobile telephone 101 performs an operation of automatically transmitting a “switch request signal”.

A specific method for transmitting a command from the data terminal device 104 to the data communication terminating device 103 is as follows.
The user may press a keyboard (not shown) of the data terminal device 104 and input “ATA” (211).

Data communication terminating device 10 which has received the command
3 starts a physical connection protocol using the mobile data communication adapter 102 and the modem carrier signal “ANS”. When this physical connection protocol ends, the connection between the data communication terminating device 103 and the mobile data communication adapter 102 is completed. When the physical connection protocol between the protocol conversion device 111 and the data terminal device 122 and the physical connection protocol between the mobile data communication adapter 102 and the data communication termination device 103 are completed, the mobile data communication adapter 102 And protocol converter 11
1 between "LRCTX" (Link Request Code
for Transmitting) (212) and “LRRCX” (Link
The wireless protocol based on (Request Code for Receiving) (213) is started, and at the same time as the completion, the state becomes the data communication state (214).

Incidentally, the communication partner of the mobile telephone 101 may be a mobile communication subscriber. In such a case, it is assumed that the other party operates the mobile phone and inputs "ATD" in order to shift to data communication. At this point, a "switching request signal" is sent from the mobile telephone 101 in the same manner as the "switching request signal" is sent to the mobile telephone exchange 107. For this reason, the time division switch 108 is controlled at the time when this is received and detected by the switching request signal detecting device 112, and the sound signal transmitting device 109 is controlled.
The connection between the input channel of the time division switch 108 to which the audio signal is input from and the communication channel of the output channel related to the communication partner is released. Then, the time division switch 10 related to the communication partner of the protocol conversion device 111
8 and the input / output channel relating to the communication partner of the mobile telephone 101 are connected, and at the same time, the input / output channel of the protocol converter 111 of the protocol converter 111 in the direction of the radio base station / base station control station 106 is moved. An input / output channel related to the communication channel of the mobile phone 101 can be connected.

[0047]

As described above, according to the first aspect of the present invention, when the digital mobile communication subscriber terminal switches from voice communication to data communication, the mobile telephone exchange side switches from the voice communication to the communication partner. Because we decided to send an audible signal in data transmission that prompts the user to make a transition in outgoing mode, even if the digital mobile communication subscriber does not have any special knowledge about the operation at the time of switching the communication, we understand the contents. Thus, it is possible to smoothly shift to data communication. Further, since the mobile telephone exchange is provided with a facility for this, it is possible to easily improve or change the content of the audio signal, for example.

According to the second aspect of the present invention, the same effects as those of the first aspect of the invention can be obtained. In addition, since protocol conversion means is provided, a data transmission protocol for a wireless section and a data transmission protocol for a wired section are provided. Are mutually converted, error control is independently performed in a section where transmission quality is poor, and transmission quality can be improved.

Further, according to the third aspect of the invention, the same effects as those of the first and second aspects of the invention can be obtained, and the other party of the communication has shifted from voice communication to data communication by the shift detecting means. Is detected, and at this time, the transmission of the acoustic signal by the acoustic signal transmitting means is stopped by the acoustic signal transmitting means stopping means. Therefore, the influence of the acoustic signal when data communication starts can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a mobile data communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a specific configuration of an audio signal transmitting device.

FIG. 3 is a block diagram showing a specific configuration of a switching request signal detection device.

FIG. 4 is a block diagram illustrating a specific configuration of a protocol conversion device.

FIG. 5 is an explanatory sequence diagram showing an operation of the mobile data communication system.

FIG. 6 is a block diagram showing an example of a conventionally proposed mobile data communication system.

[Explanation of symbols]

 Reference Signs List 101 mobile telephone (MS) 102 mobile data communication adapter (ADP) 103 data communication termination device (MDa) 104 data terminal device (PCa) 106 wireless base station / base station control station (BSS) 107 mobile telephone exchange ( MSC) 108 Time division switch (TDSW) 109 Acoustic signal transmission device (TONE) 111 Protocol conversion device (IWF) 112 Switching request signal detection device (DET) 114 Mobile telephone exchange control device (CC) 121 General public switched telephone network (PSTN) ) 122 data terminal device (MDb) 123 data terminal device (PCb) 124 telephone 138 arithmetic processing circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04L 29/06 H04M 3/00 11/00 302

Claims (4)

[Claims] 1. A digital mobile communication subscriber terminal, and a switch request signal detecting means for detecting when the digital mobile communication subscriber terminal outputs a switch request signal for switching voice communication to data communication, A mobile unit comprising, when the switching request signal detecting means detects the switching request signal, an acoustic signal transmitting means for transmitting an acoustic signal for prompting the other party of communication to shift from voice communication to data communication in the transmission mode. A mobile data communication system comprising a telephone exchange. 2. A digital mobile communication subscriber terminal, and a switching request signal detecting means for detecting when the digital mobile communication subscriber terminal outputs a switching request signal for switching voice communication to data communication, When the switching request signal detecting means detects the switching request signal, an audio signal sending means for sending an audio signal to the other party of the communication to prompt a transition from voice communication to data communication in the transmission mode,
A mobile data communication system comprising: a mobile telephone exchange provided with protocol conversion means for converting between a wireless section data transmission protocol and a wired section data transmission protocol. 3. A digital mobile communication subscriber terminal, and a switch request signal detecting means for detecting when the digital mobile communication subscriber terminal outputs a switch request signal for switching voice communication to data communication, When the switching request signal detecting means detects the switching request signal, an audio signal sending means for sending an audio signal to the other party of the communication to prompt a transition from voice communication to data communication in the transmission mode,
Protocol conversion means for mutually converting between a data transmission protocol in a wireless section and a data transmission protocol in a wired section;
Transition detection means for detecting that the communication partner has shifted from voice communication to data communication, and transmission of an acoustic signal by the acoustic signal transmission means when the transition detection means detects transition from voice communication to data communication. A mobile data communication system comprising: a mobile telephone exchange provided with an audio signal transmitting means stopping means for stopping the communication. 4. The mobile data communication system according to claim 1, wherein the communication partner is a digital mobile communication subscriber terminal or a subscriber terminal of a general public telephone network.