JPH0697906A - Multi-media multiplexing device - Google Patents

Abstract

PURPOSE:To improve the compression efficiency of a facsimile signal modulated to a voice band, so as to become the same level as the compression efficiency of other voice signal than the facsimile signal. CONSTITUTION:In a voice channel, a facsimile signal converting part 3 decides whether a voice signal transmitted from a voice terminal is a facsimile signal modulated to a voice band or not, and in the case it is decided to be the facsimile signal, the facsimile signal concerned is converted into a digital signal, and adjusts it so as to become the same speed as a speed of the sound signal compressed by a voice compressing/expanding part 2. Thereafter, it is outputted to a demultiplexing device by controlling a compressed signal selector 4. Also, in the case it is decided that the sound signal transmitted from the voice terminal is not the facsimile signal modulated to the voice band, the facsimile signal converting part 3 outputs the sound signal compressed by the voice compressing/ expanding part 2 to the demultiplexing device by controlling the compressed signal selector 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multimedia multiplexer, and more particularly to a multimedia multiplexer suitable for accommodating a voice terminal such as a private branch exchange (PBX).

[0002]

2. Description of the Related Art Conventionally, a voice signal transmitted from a voice terminal and a data signal transmitted from a data terminal are multiplexed and transmitted to a line, and the multiplexed signal transmitted from the line is transmitted as a voice signal. Various techniques have been devised for devices that separate signals and data signals and distribute them to voice terminals and data terminals. In this type of device, in order to improve the line accommodation efficiency, for example, 64
The audio signal transmitted at Kbps is compressed to 32 Kbps. Furthermore, 16 Kbp
Compressing process to compress to s (APC method: Adapti
ve Predictive Coding) has also been put to practical use.

[0003]

A voice signal transmitted from a voice terminal may include a facsimile signal modulated in a voice band. Conventionally, such a facsimile signal is also a voice signal other than that. Both of them perform the same compression processing.

However, when the facsimile signal is compressed to 16 Kbps, the original 64
When decompressing to Kbps, it cannot be accurately restored.

Therefore, for example, JP-A-62-14353 is used.
As with the technique described in No. 1, voice signals other than facsimile signals can be compressed to 16 Kbps, but the entire voice signal must be compressed to 32 Kbps. Will be left behind.

An object of the present invention is to improve the compression efficiency of a facsimile signal modulated in the voice band so as to be at the same level as the compression efficiency of voice signals other than the facsimile signal.

[0007]

In order to achieve the above object, the present invention provides a facsimile signal which is installed between a voice terminal and a data terminal and a line and which is modulated in a voice band with the voice terminal. One or more voice channels for transmitting and receiving voice signals, one or more data channels for transmitting and receiving data signals to and from the data terminal, and voice signals received by the voice channels and received by the data channels. A multiplexed / demultiplexed device that multiplexes the data signal and transmits it to the line, separates the multiplexed signal transmitted from the line into a voice signal and a data signal, and distributes to the corresponding voice channel and data channel. Provided is a multimedia multiplexing device having the same.

In the multimedia multiplexer of the present invention, the voice channel is provided with a voice compression / decompression unit, a facsimile signal conversion unit, a compression signal selector and a voice signal selector.

The voice compression / decompression unit has a compression means for compressing the voice signal transmitted from the voice terminal and a decompression means for decompressing the voice signal distributed by the multiplexer / demultiplexer.

The facsimile signal conversion section comprises first judging means for judging whether or not the voice signal transmitted from the voice terminal is a facsimile signal modulated into a voice band.
First conversion means for converting a voice signal transmitted from a voice terminal into a digital signal, and when the first judgment means judges that the signal is a facsimile signal, the first conversion means converts it into a digital signal. First adjusting means for adjusting the speed of the reproduced facsimile signal to the same speed as the speed of the audio signal compressed by the compressing means of the audio compressing / expanding section, and the audio signal distributed by the multiplexer / demultiplexer. Is a facsimile signal, and when the second determining means determines that it is a facsimile signal, the speed of the facsimile signal is adjusted to the original speed. A second adjusting means and a second converting means for converting the facsimile signal adjusted to the original speed by the second adjusting means into an analog signal are provided. That.

Further, the compressed signal selector is any one of the voice signal compressed by the compression means of the voice compression / decompression section and the facsimile signal whose speed is adjusted by the first adjustment means of the facsimile signal conversion section. Is output to the multiplexer / demultiplexer, and the audio signal selector is configured to output the audio signal expanded by the expansion means of the audio compression / expansion unit and the second signal of the facsimile signal conversion unit.
One of the facsimile signals converted into the analog signal by the converting means is output to the voice terminal.

Therefore, when the facsimile signal converting section further judges that the first judging means is a facsimile signal, the compressed signal selector adjusts the speed by the first adjusting means of the facsimile signal converting section. When the first switching means for switching the outputted facsimile signal to the multiplexer / demultiplexing device and the second judging means judge that the facsimile signal is a facsimile signal, the voice signal selector causes the facsimile signal conversion section to operate. A second switching unit that switches to output the facsimile signal converted into the analog signal by the second converting unit to the voice terminal is provided.

The first part of the facsimile signal conversion section
When the voice signal converted into the digital signal by the first converting means includes a preamble signal which is data of a specific pattern indicating the beginning of the frame of the facsimile procedure signal, Can be determined to be a facsimile signal.

The first of the facsimile signal conversion units
When the first judging means judges that the facsimile signal is a facsimile signal, the adjusting means adds the information indicating the facsimile signal to the facsimile signal converted into the digital signal by the first converting means. Further, by adding dummy information so that the format length is the same as the format length of the voice signal compressed by the compression means of the voice compression / decompression unit, the speed of the facsimile signal can be increased by the voice compression / decompression. The speed can be adjusted so as to be the same as the speed of the audio signal compressed by the compression means of the unit.

In this case, the second adjusting means of the facsimile signal converting section removes the part of the facsimile signal distributed by the multiplexer / demultiplexer from which the information indicating the facsimile signal and the dummy information are removed. By taking it out, the speed of the facsimile signal is adjusted to the original speed.

Then, the second judging means of the facsimile signal converting section, when the information indicating the facsimile signal is added to the audio signal distributed by the multiplexer / demultiplexing device, the audio signal is outputted. Can be determined to be a facsimile signal.

[0017]

When the voice signal transmitted from the voice terminal is not the facsimile signal modulated in the voice band, the voice signal is compressed by the voice compression / decompression unit in the voice channel and then transmitted to the multiplexer / demultiplexer. Is output.

Further, when the voice signal transmitted from the voice terminal is a facsimile signal modulated in the voice band, the voice signal (facsimile signal) is converted into a digital signal by the facsimile signal conversion section in the voice channel. After being converted and adjusted to have the same speed as the speed of the audio signal compressed by the audio compression / decompression unit,
Output to the multiplexer / demultiplexer.

Further, the data signal transmitted from the data terminal is directly output to the multiplexer / demultiplexer in the data channel.

Then, the voice signal output from the voice channel and the data signal output from the data channel are multiplexed in the multiplexer / demultiplexer and transmitted to the line.

On the other hand, the multiplexed signal transmitted from the line is separated into a voice signal and a data signal by a multiplexer / demultiplexer and distributed to the corresponding voice channel and data channel.

When the voice signal distributed by the multiplexer / demultiplexer is a voice signal other than the facsimile signal, the voice signal is expanded in the voice channel by the voice compression / decompression unit and then output to the voice terminal. To be done.

When the voice signal distributed by the multiplexer / demultiplexer is a facsimile signal, the voice signal (facsimile signal) is adjusted to the original speed by the facsimile signal conversion unit in the voice channel and analogized. It is converted to a signal and then output to the voice terminal.

Therefore, according to the present invention, the compression efficiency of the facsimile signal can be improved to the same level as the compression efficiency of the voice signal other than the facsimile signal.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a network to which the multimedia multiplexer of this embodiment is applied.

In FIG. 1, the multimedia multiplexers of this embodiment are connected to each other via a high speed digital line.

Further, in each of the multimedia multiplexers, a P accommodating a telephone and a facsimile machine is provided.
A voice channel for transmitting / receiving a voice signal that may include a facsimile signal modulated in a voice band with a voice terminal such as a BX, a data channel for transmitting / receiving a data signal with a data terminal, and a reception by the voice channel The multiplexed voice signal and the data signal received by the data channel are multiplexed and transmitted to the high-speed digital line, and the multiplexed signal transmitted from the high-speed digital line is separated into the voice signal and the data signal, which are applicable. And a multiplexer / demultiplexer for distributing to voice channels and data channels.

In FIG. 1, there are two audio channels.
The number of data channels is two, and the number of data channels is two.
It does not specify these numbers.

FIG. 2 is a block diagram of the multimedia multiplexing apparatus of this embodiment.

In FIG. 2, the portion corresponding to the voice channel is the voice terminal interface unit 1 and the voice / facsimile signal processing unit 8, and the portion corresponding to the data channel is the data terminal interface unit 9. Also,
The parts equivalent to the multiplexer / demultiplexer are the multiplexer / demultiplexer 6 and the high-speed digital line interface unit 7.

The voice / facsimile signal processing unit 8 comprises a voice compression / decompression unit 2, a facsimile signal conversion unit 3, a compressed signal selector 4 and a voice signal selector 5.

FIG. 2 shows the case where there is one voice channel and one data channel.

In the voice channel, the voice terminal interface section 1 receives a voice signal transmitted from the voice terminal as an analog signal or a digital signal at 64 Kbps.
To a voice compression / expansion unit 2 and a facsimile signal conversion unit 3. At this time, the voice signal may be a human voice, a signal sound from a voice terminal such as a PB signal, or a facsimile signal modulated in a voice band.

The voice compression / decompression unit 2 converts the voice signal output from the voice terminal interface unit 1 into an APC system (Ad
aptive Predictive Coding) and other compression processes
It is converted into a 6 Kbps digital signal and output to the compressed signal selector 4.

The compressed signal selector 4 normally multiplexes the audio signal output from the audio compression / decompression unit 2 with the multiplexing / demultiplexing unit 6.
According to the switching signal transmitted from the facsimile signal conversion unit 3 only when the voice signal transmitted from the voice terminal is a facsimile signal modulated in the voice band. Voice signals (facsimile signals) sent from
It operates so as to output to the separation unit 6. The operation of the facsimile signal converter 3 will be described later.

In the data channel, the data terminal interface unit 9 multiplexes the data signal transmitted from the data terminal as a digital signal as it is.
Output to the separation unit 6.

Therefore, in the multiplexer / demultiplexer, if the voice signal is not a facsimile signal modulated in the voice band, the voice compression / decompression unit 2 of the voice / facsimile signal processing unit 8 outputs the voice signal from the voice channel. A voice signal (other than a facsimile signal) is output, and if the voice signal is a facsimile signal modulated in the voice band, it is output from the facsimile signal conversion unit 3 of the voice / facsimile signal processing unit 8. A voice signal (facsimile signal) will be output. In addition, the data signal output from the data terminal interface unit 9 is output from the data channel.

In the multiplexer / demultiplexer, the multiplexer / demultiplexer 6 multiplexes the voice signal output from the voice channel and the data signal output from the data channel and, via the high-speed digital line interface unit 7,
Send to high-speed digital line.

On the other hand, in the multiplexer / demultiplexer, when the multiplexed signal transmitted from the opposing multimedia multiplexer via the high-speed digital line is received via the high-speed digital line interface unit 7, the multiplexer / demultiplexer receives the multiplexed / demultiplexer. The unit 6 separates the received multiplexed signal into a voice signal and a data signal and distributes them to the corresponding voice channel and data channel.

In the voice channel, the distributed voice signal is compressed by the voice / facsimile signal processing unit 8.
Output to the decompression unit 2 and the facsimile signal conversion unit 3,
The audio compression / decompression unit 2 regards this audio signal as a compressed audio signal, converts it into a 64 Kbps PCM signal, and
Output to the audio signal selector 5.

The voice signal selector 5 normally operates to output the voice signal output from the voice compression / decompression unit 2 to the voice terminal interface unit 1, and only when the voice signal is a facsimile signal. The voice signal (facsimile signal) output from the facsimile signal conversion unit 3 is output to the voice terminal interface unit 1 according to the switching signal output from the facsimile signal conversion unit 3. The operation of the facsimile signal converter 3 will be described later.

The voice terminal interface section 1 transmits the voice signal output from the voice signal selector 5 to the voice terminal.

Further, in the data channel, the data terminal interface section 9 sends the distributed data signal
As it is, it is transmitted to the data terminal.

Next, the structure and operation of the facsimile signal converter 3 will be described.

FIG. 3 is a block diagram of the facsimile signal converter 3.

In the figure, 10 is a PCM codec, 11 is a facsimile modem, and 12 is a microprocessor.

The PCM codec 10 once converts the voice signal output from the voice terminal interface section 1 into an analog signal and outputs it to the facsimile modem 11. The facsimile modem 11 converts the voice signal output from the PCM codec 10 into a digital signal and outputs the digital signal to the microprocessor 12.

The voice signal output from the facsimile modem 11 is input to the serial port of the microprocessor 12, and the microprocessor 12 inputs the voice input with the preamble signal which is the data of the specific pattern indicating the beginning of the frame of the facsimile procedure signal. It is determined whether or not it is included in the signal, and if it is included, it is determined that the input voice signal is a facsimile signal.

When the microprocessor 12 determines that the input voice signal is a facsimile signal, the microprocessor 12 has the same speed as the speed of the voice signal compressed by the voice compression / expansion unit 2 (that is, The same format length) is adjusted by adding a fixed header and dummy bits to the facsimile signal and output from the serial port to the compressed signal selector 4.

FIG. 4 shows an example of the format of a 16 Kbps voice compression signal and the format of a facsimile signal in which a constant header and dummy bits are added so as to have the same speed as the speed of the voice compression signal.

In FIG. 4, a 16 Kbps audio signal is divided into 240 bits every 20 msec to form one frame. The first to third bits of the frame have a fixed pattern "110" for identifying the frame. Also, the fourth bit is set to "0" when the frame contains compressed audio data, and is set to "1" when the frame contains a facsimile signal.

That is, in the audio compression signal output from the audio compression / decompression unit 2 to the compressed signal selector 4, the first to fourth bits are "1100" and the fifth to 24th bits.
Compressed audio data is set to the 0th bit. Further, the first to fourth bits of the facsimile signal output from the facsimile signal conversion unit 3 to the compressed signal selector 4 are "1101", and the fifth to 240th bits of the facsimile signal are set. Depending on the speed, dummy bits are added to the actual facsimile information up to the 240th bit.

For example, the audio compression signal is 16 Kbps,
When the facsimile signal is 9.6 Kbps, since the facsimile signal has 192 bits of information within 20 msec of one frame, as shown in FIG. 4, the facsimile information is set in the 5th bit to the 196th bit. 19
Dummy bits are added to the 7th to 240th bits.

As can be seen from this, when compressing the audio signal, the audio compression / decompression unit 2 sets a fixed pattern "110" for frame identification in the first bit to the third bit. "0" indicating that the compressed audio data is included is set in the 4th bit, and the compressed audio data is set in the 5th bit to the 240th bit.

Now, returning to FIG. 3, when the microprocessor 12 determines that the voice signal output from the voice terminal interface section 1 is a facsimile signal, it outputs a switching signal to the voice signal selector 5, and the facsimile signal is output. The facsimile signals output from the signal conversion unit 3 are multiplexed.
The audio signal selector 5 is switched so as to be output to the separation unit 6.

On the other hand, the microprocessor 12 is
It is determined whether or not the fourth bit of the frame of the audio signal distributed by the separating unit 6 is "1", and if it is "1", it is determined that the distributed audio signal is a facsimile signal. .

Then, when the microprocessor 12 determines that the distributed voice signal is a facsimile signal, from among the facsimile signals of the 5th bit and thereafter,
The actual facsimile information excluding the dummy bits is taken out and output to the facsimile modem 11. The facsimile modem 11 converts the facsimile signal output from the microprocessor 12 into an analog signal and outputs the analog signal to the PCM codec 10. The PCM codec 10 converts the facsimile signal output from the facsimile modem 11 into a PCM signal and outputs the PCM signal to the voice signal selector 5.

At this time, the microprocessor 12 outputs a switching signal to the audio signal selector 5, and P
The voice signal selector 5 is switched so that the facsimile signal output from the CM codec 10 is output to the voice terminal interface unit 1.

When the end of the call is detected or the microprocessor 12 detects the end of the facsimile communication, the compressed signal selector 4 outputs the audio signal output from the audio compression / decompression unit 2 as usual. The audio signal selector 5 operates to output to the multiplexer / demultiplexer 6, and the audio signal selector 5 operates to output the audio signal output from the audio compressor / decompressor 2 to the audio terminal interface unit 1 as usual.

As described above, according to this embodiment,
When the voice signal transmitted from the voice terminal is not the facsimile signal modulated in the voice band, the voice signal is compressed by the voice compression / decompression unit 2 and then multiplexed and transmitted to the high speed digital line. It When the voice signal transmitted from the voice terminal is a facsimile signal modulated in the voice band, the facsimile signal is converted into a digital signal by the facsimile signal conversion unit 3 to have the same format as the voice compression signal. It is conditioned, then multiplexed and transmitted on a high speed digital line.

Therefore, even with a facsimile signal, it is possible to obtain the same level of compression efficiency as that of a voice signal other than a facsimile signal.

Further, according to the present embodiment, it becomes possible to transmit / receive to / from the voice terminal on the same voice channel, whether it is a facsimile signal or a voice signal other than the facsimile signal.

In the present embodiment, the speed of the voice compression signal has been described as 16 Kbps, but the present invention is not limited to this, and the same format can be obtained by changing the format of FIG. 4 according to the speed of the voice compression signal. The effect can be obtained.

If the speed of the facsimile signal is higher than that of the voice compression signal, the microprocessor 1
In step 2, the facsimile signal is further compressed, or the speed of the facsimile signal is fallback to enable transmission.

[0066]

As described above, according to the multimedia multiplexer of the present invention, a voice signal in which a facsimile signal modulated in a voice band is converted into a digital signal and a voice signal other than the facsimile signal is compressed By adjusting so that the speed is the same as that of the compressed signal, and then multiplexing and transmitting, the compression efficiency of the facsimile signal can be improved to the same level as the compression efficiency of the voice signal other than the facsimile signal. is there.

[Brief description of drawings]

FIG. 1 is a block diagram of a network to which a multimedia multiplexer of this embodiment is applied.

FIG. 2 is a block diagram of a multimedia multiplexing apparatus of the present embodiment.

FIG. 3 is a configuration diagram of a facsimile signal conversion unit.

FIG. 4 is an explanatory diagram showing an example of a format of a voice compression signal and a format of a facsimile signal.

[Explanation of symbols]

1 ... Voice terminal interface unit, 2 ... Voice compression / decompression unit, 3 ... Facsimile signal conversion unit, 4 ... Compressed signal selector, 5 ... Voice signal selector, 6 ... Multiplexing / separating unit, 7 ... High-speed digital line interface unit, 8 ... voice / facsimile signal processing unit, 9 ... data terminal interface unit,
10 ... PCM codec, 11 ... Facsimile modem,
12 ... Microprocessor.

Claims (9)

[Claims] 1. A voice signal which is installed between a voice terminal and a data terminal and a line and which transmits and receives a voice signal which may include a facsimile signal modulated in a voice band to and from the voice terminal.
One or more data channels for transmitting and receiving data signals to and from one or more voice channels, a voice signal received by the voice channels, and a data signal received by the data channels are multiplexed and transmitted to the line. Then
A multimedia multiplexer including: a multiplexer / demultiplexer that separates a multiplexed signal transmitted from a line into a voice signal and a data signal and distributes the voice signal and the data channel to the corresponding voice channel and data channel, The voice channel compresses the voice signal transmitted from the voice terminal and multiplexes it.
A voice compression / decompression unit for decompressing the voice signal distributed by the separating device, and, when the voice signal transmitted from the voice terminal is a facsimile signal modulated in the voice band, converts the facsimile signal into a digital signal. When the voice signal distributed by the multiplexer / demultiplexer is a facsimile signal, the speed of the facsimile signal is adjusted so that the speed becomes the same as the speed of the audio signal compressed by the audio compression / decompression unit. The speed is adjusted by adjusting to the original speed and converting it into an analog signal by a facsimile signal conversion unit, the voice signal compressed by the voice compression / decompression unit, and the digital signal by the facsimile signal conversion unit. A compressed signal selector for outputting any one of the facsimile signals that have been output to the multiplexer / demultiplexer; And a voice signal selector for outputting to the voice terminal one of the voice signal expanded by the expansion unit and the facsimile signal whose speed has been adjusted by the facsimile signal conversion unit and converted into an analog signal. A multimedia multiplexing device characterized by. 2. The multimedia multiplexing apparatus according to claim 1, wherein the audio compression / decompression unit compresses an audio signal transmitted from an audio terminal, and audio distributed by the multiplexer / demultiplexer. Decompressing means for decompressing the signal, wherein the facsimile converting section determines whether the voice signal transmitted from the voice terminal is a facsimile signal modulated into a voice band, First converting means for converting a voice signal transmitted from a voice terminal into a digital signal, and when the first determining means determines that the signal is a facsimile signal, the first converting means converts it into a digital signal. First adjusting means for adjusting the speed of the received facsimile signal so as to be the same speed as the speed of the voice signal compressed by the compression means of the voice compression / decompression unit, Second judging means for judging whether or not the voice signal distributed by the demultiplexing / separating device is a facsimile signal, and the speed of the facsimile signal when the second judging means judges that it is a facsimile signal Of the facsimile signal adjusted to the original speed by the second adjusting means, and second converting means for converting the facsimile signal adjusted to the original speed by the second adjusting means into an analog signal. And multimedia multiplexer. 3. The multimedia multiplexing apparatus according to claim 2, wherein the facsimile signal converting section further comprises: when the first determining means determines that the facsimile signal is a facsimile signal, When the first switching means for switching the facsimile signal whose speed has been adjusted by the first adjusting means of the facsimile signal converting section so as to be output to the multiplexer / demultiplexing device and the second determining means determine that it is a facsimile signal. In addition, the voice signal selector has second switching means for switching the facsimile signal converted into the analog signal by the second converting means of the facsimile signal converting section to output to the voice terminal. Media multiplexer. 4. The multimedia multiplexing apparatus according to claim 2 or 3, wherein the first judging means of the facsimile signal converting section converts a voice signal converted into a digital signal by the first converting means into a facsimile signal. A multimedia multiplexing device, characterized in that when a preamble signal, which is data of a specific pattern indicating the beginning of a frame of a procedure signal, is included, the voice signal is judged to be a facsimile signal. 5. The multimedia multiplexing apparatus according to claim 2, 3 or 4, wherein the first adjusting means of the facsimile signal converting section determines that the first determining means is a facsimile signal. , A format length of the voice signal compressed by the compression means of the voice compression / decompression unit by adding information indicating the facsimile signal to the facsimile signal converted into the digital signal by the first conversion means. By adjusting the speed of the facsimile signal to be the same speed as the speed of the audio signal compressed by the compression means of the audio compression / decompression unit by adding dummy information so that the same format length as A multimedia multiplexing device characterized by. 6. The multimedia multiplexing apparatus according to claim 5, wherein the second adjusting means of the facsimile signal converting section is the facsimile signal among the facsimile signals distributed by the multiplexing / demultiplexing apparatus. Is extracted and the portion excluding the dummy information is adjusted to adjust the speed of the facsimile signal to the original speed. 7. The multimedia multiplexing apparatus according to claim 5 or 6, wherein the second judging means of the facsimile signal converting unit is the voice signal distributed by the multiplexing / demultiplexing apparatus and the facsimile signal. The multimedia multiplexing apparatus is characterized in that the voice signal is judged to be a facsimile signal when the information indicative of is added. 8. A voice signal transmitted from a voice terminal, which may include a facsimile signal modulated in a voice band, is output to a multiplexer / demultiplexer, and a voice signal distributed by the multiplexer / demultiplexer is output. In the voice channel to be sent to the voice terminal, the function to compress the voice signal sent from the voice terminal, and the compressed voice if the voice signal sent from the voice terminal is not a facsimile signal modulated in the voice band. A function of outputting a signal to a multiplexer / demultiplexer and, when a voice signal transmitted from a voice terminal is a facsimile signal modulated into a voice band, converts the facsimile signal into a digital signal and a voice compression / decompression unit It has a function of adjusting the speed to the same speed as the speed of the audio signal compressed by Voice channel that. 9. A voice channel according to claim 8, wherein the function of expanding the voice signal distributed by the multiplexer / demultiplexer and the function of expanding the voice signal distributed by the multiplexer / demultiplexer are not facsimile signals. A function to send a voice signal to a voice terminal, and when the voice signal distributed by the multiplexer / demultiplexer is a facsimile signal, the speed of the facsimile signal is adjusted to the original speed and converted to an analog signal. A voice channel having a function of transmitting to a voice terminal afterwards.