JP2902775B2 - Button phone system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a key telephone system having a plurality of data terminals in an extension.

(Prior Art) In this key telephone apparatus, a MODEM for modulating and demodulating data is provided to enable communication between an extension data terminal and a public telephone network. In this case, since it is uneconomical to provide expensive MODEMs for each terminal, one or a small number of MODEMs are pooled, and communication with the pooled MODEMs is required only when communicating with the public telephone network. Data terminals to be selectively connected. This is called modem pooling.

In such a conventional system, when transmitting from a motor terminal or receiving from a network, a central control unit that handles call processing and exchange transmits and receives control commands to and from a MODEM and a data terminal via an RS-232D interface. , Those RS
Analyzes the transmission / reception data of −232D and sets the MODE
It controls call processing such as mode control of M, calling of data terminals, and connection of communication paths between the two. Further, in parallel with this, control of communication path connection between the MODEM and the network is also performed. At this time, the MODEM performs an automatic calling / receiving operation according to a procedure such as V.25bis recommended by CCITT. In this case, in order to prevent data loss or the like, it is necessary to finely control the order and timing of connection of communication channels.

(Problems to be Solved by the Invention) As described above, in the key telephone system adopting the conventional model pooling, since the processing to be performed by the central control unit at the time of making and receiving calls is complicated, the load becomes heavy. is there.

Accordingly, an object of the present invention is to reduce the load on the central processing unit when making and receiving calls in a key telephone system in which models are pooled.

[Configuration of the invention]

(Means for Solving the Problems) The present invention is connected to an office line that can provide a dial-in service, a plurality of data terminals are connected to an extension, and these data terminals are made accessible to the office line. 2
More than one MODEMs are pooled, and these MODEMs have a built-in network controller and have a function of performing an automatic call originating / terminating procedure for the data terminal.
In a key telephone system provided with an exchange unit for forming and disconnecting a communication path between DEMs, a terminal attribute storage unit for storing each attribute of the data terminal, and a MODEM attribute storage unit for storing each attribute of the MODEM Terminal selection means for selecting one data terminal based on an extension designation signal of a dial-in service given from the office line when receiving an incoming call from the office line; and MODEM selecting means for recognizing the attribute of the data terminal, and selecting one MODEM having an attribute matching this attribute by referring to the MODEM attribute recognizing means, controlling the exchange means, Forming a communication path between the selected data terminal and the selected MODEM, thereby forming a communication path between the selected data terminal and the selected MODEM.
First switching control means for making a connection as if they were directly connected, and MODEM calling means for giving a calling signal to the selected MODEM after forming a communication path between the selected data terminal and the selected MODEM. Receiving the response of the selected MODEM to the paging signal, controlling the exchange means and selecting the selected MO
Forming a communication path between the DEM and said office line, whereby said selected MODE between said selected data terminal and said office line;
And a second exchange control means for forming a communication path via M.

(Operation) In the system of the present invention, when an incoming call is received using a dial-in service from an office line, the data terminal specified by the dial-in service extension designation signal and the A MODEM having the same attribute is selected, and a communication path between them is connected. As a result, the data terminal and the MODEM are in the same state as if they were directly connected, so that transmission and reception of control commands, their analysis, and control based on them are performed between them, and the data interface and system central processing are performed. The part does not need to be involved and their load is reduced.

(Embodiment) FIG. 1 shows a system configuration of an embodiment of a key telephone system according to the present invention.

The main unit 1 includes a control unit 3 which mainly performs call processing and communication path switching, a data highway 5 which is a control data transmission path, a PCM highway 7 which is a time division communication path, and various interface units 9, 11, 13, 15, 15, Including 17,19. The they interface unit Specifically, the digital telephone 27 ₁ ~ 27 _n and data office line interface unit 11 ₁ to 11 _m for connecting the office line 25 ₁ to 25 _m of the public telephone network (analog network), as an extension Digital telephone interface unit 13 ₁ for connecting interface unit 31
To 13 _n, 17, and a standard telephone interface unit 21 for connecting the standard telephone as an extension.

Digital telephone interface unit 13 of main unit 1
₁ The to 13 _i, at the rate of one interface unit, for example, of eight phones, the total n-number of digital telephones 27 ₁
~ 27 _n are connected. Each digital telephone 27 has a main unit 1
A telephone circuit 33 having a function of internally performing A / D and D / A conversion of an audio signal transmitted and received in the form of a digital signal between the telephone circuit 33 and relay of digital signal communication between the telephone circuit 33 and the main device 1. The data interface unit 35 is incorporated. The data interface unit 35 can be connected to a data terminal 37 having an RS-232D interface, and transmits and receives RS-232D transmission data (SD) and reception data (RD) communicated with the data terminal 37. ) Is converted into a format of data exchanged with the main device 1.

This system, j stand model (MODEM) 43 ₁ ~43 _j are pooled.

MODEM43 ₁ ~43 _j is a device for modulating and demodulating the data to allow fly data terminal 37 with the RS-232D interface to the public telephone network, network control unit (NCU)
It is possible to carry out outgoing / incoming call procedures for data terminals using the RS-232D transmission data (SD) and reception data (RD). These MODEMs 43 ₁ to 43 _j are divided into several groups according to their data rates. For example, it is divided into three groups having data rates of 300 bps, 1200 bps, and 2400 bps, respectively.

The terminal for connection of the public telephone network of each MODEM 43 is connected to the standard telephone interface unit 21 of the main unit 1, while
The terminal for data terminal connection is connected to the digital telephone interface unit 17 of the main device 1 via the data interface unit 31. The data interface unit 31 interposed between the MODEM 43 and the digital telephone interface unit 17 has a configuration almost similar to the data interface unit 35 in the digital telephone 27 except for differences in details. RS-232D transmission data (SD) and reception data (R
D) is converted into a format of data exchanged with the digital telephone interface unit 17.

The control unit 3 in the main unit 1 includes a microcomputer 49 for performing call processing, and a time switch circuit for exchanging voice and data by interconnecting time-division communication paths in the PCM highway under the control of the microcomputer 49. MF for detecting an MP signal (selection signal obtained by mixing two frequencies) sent from the station line 25 and communicating with the microcomputer 49
Includes receiver 53.

In this system, when the data terminal 37 performs data communication with an external data device through a public telephone network, the station line 25 station line interface unit 11PCM highway 7 standard telephone interface unit 21MODEM43R
S-232D interface 47 Data interface unit 31 Digital telephone interface unit 17PC
A communication path is formed by the path of the M highway 7 digital telephone interface unit 13 data interface unit 35 RS-232D interface 39 data terminal 37.

One feature of this system is that when forming the communication path in response to an incoming call from the office line 25, the load on the microcomputer 49 is minimized by using a dial-in service provided from a public telephone network. The point is that the above-mentioned communication path is formed in a procedure as follows.

 Hereinafter, the configuration of each unit of the system will be described in detail.

FIG. 2 shows the configuration of the data interface unit 35 in the digital telephone 27.

The data interface unit 35 includes a ping-pong transmission circuit 55 for performing half-duplex communication of digital signals with the digital telephone interface unit 13 of the main device 1 by two lines, and a telephone control microcomputer for controlling the telephone circuit 33. 57, a data communication control microcomputer 59 for controlling the data terminal 37, an RS-232D interface driver / receiver 61 for performing level conversion of various signals communicated with the data terminal 37 via the RS-232D interface 39, etc. including.

The ping-pong transmission circuit 55 has two B bits having a speed of 64 Kbps.
A digital signal is ping-pong transmitted to and from the main apparatus 1 using a 2B + D format time-division channel composed of one channel (B1 and B2 channels) and one D channel having a speed of 16 Kbps. As shown in FIG. 3, the ping-pong transmission circuit 49 receives the uplink data of each channel, combines it into a data packet of 2B + D format, and transmits it to the main unit 1 to transmit it to the main unit 1.
And a 2B + D separation circuit that receives a downstream data packet in the form of 2B + D from the main unit 1 and separates the data into data for each channel.
67. Here, the B1 channel is used for transmitting voice data transmitted and received by the telephone circuit 33 during the telephone call,
The channel is allocated to transmission of communication data transmitted and received during data communication by the data terminal 37, and the data of the D channel is allocated to transmission of control data transmitted and received by the microcomputers 57 and 59 for telephone control and data communication control. That is,
The voice data transmitted from the telephone circuit 33 during a call is B1 channel uplink data B1-IN, the communication data transmitted from the data terminal 37 during data communication is B2 channel uplink data B2-IN, and the microcomputer 57, The control data output from 59 enters the 2B + D creation circuit 63 as D-channel uplink data D-IN, where it is created as a 2B + D packet and sent to the main unit 1. Also, the 2B + D packet that has entered the 2B + D separation circuit 65 from the main device 1 is separated here into B1 channel downstream data B1-OUT, B2 channel downstream data B2-OUT, and D channel upstream data D-IN, respectively. It is sent to the telephone circuit 33, the data terminal 37 and the microcomputers 57 and 59.

The downlink and uplink data B2-OUT and B2-IN of the B2 channel are 8-bit serial data (64 Kbps), respectively.
Of these, 6 bits are communication data (48 Kbps), and the downlink data B2-OUT has the remaining 2 bits as RS-232D reception carrier detection signal CD (8 Kbps) and transmission enable signal CS (8 Kbps).
Kbps), and the RS-232D transmission request signal RS (8 Kbps) and transmission enable signal C as the remaining two bits in the uplink data B2-IN.
S (8 Kbps) is included. The downlink data B2-OUT is first input to a serial / parallel conversion circuit 69 to separate communication data, a received carrier detection signal CD and a transmission enable signal CS, and the communication data is further converted to a parallel / serial conversion circuit.
It is input to 71 and returned to 48Kbps serial data. The data communication data is first input to a serial / parallel conversion circuit 73 and converted into 64 Kpbs parallel data.
Next, the signal is input to the parallel / serial conversion circuit 75, and is combined with the transmission request signal RS and the transmission enable signal CS to create 8-bit uplink data B2-IN.

The telephone control microcomputer 57 has a function of controlling the telephone circuit 33 (for example, ringing a bell sound, turning on / off various displays, etc.) based on the D-channel downlink data D-OUT, and a signal from the telephone circuit 33. (Eg hook signal,
And a function of outputting control data corresponding to a selection signal to the selector 63. The selector 63 controls the telephone control microcomputer 57 and the data communication control microcomputer 59 under the control of the telephone control microcomputer 57.
Is selected and sent to the ping-pong transmission circuit 55 as D-channel upstream data D-IN. When transmitting control data, the telephone control microcomputer 57 controls the selector 63 to select its own transmission control data, and prohibits the data communication control microcomputer 59 from transmitting control data. Therefore,
Only when the telephone control microcomputer 57 does not transmit control data, the data terminal control microcomputer
59 is allowed to send control data, and the control data is sent to the main unit 1 through the D channel.

The data communication control microcomputer 59 controls the RS-232D interface called display signal CI and the data set ready signal DR to be given to the data terminal 37 based on the D channel downlink data D-OUT, A function to create and output control data to be sent to the data terminal 37,
And a function of selecting a mode between a command receiving mode and a communication mode. Here, the command reception mode is a mode in which only the data communication control microcomputer 59 accesses the transmission data SD and the reception data RD of the RS-232D. On the other hand, the communication mode is a mode in which the transmission data SD and the reception data RD of the RS-232D are transmitted / received to / from the main device 1 in a transient manner through the B2 channel. Specifically, this mode selection is performed by the selector 65 under the control of the data communication control microcomputer 59.
And 67. That is, in the communication mode, the selector 65 selects the downlink communication data from the parallel / serial conversion circuit 71 as the reception data RD, and the selector 67
The transmission data SD of RS-232D is selected and sent to the serial / parallel conversion circuit 73. On the other hand, in command reception mode,
The selector 65 is a microcomputer 59 for data communication control.
Is selected as received data RD, and the selector 67 selects a high-level constant signal (meaning no data) from the power supply V.

The data terminal control microcomputer 59 further includes:
It also has a function of creating control data to be sent to the main unit 1 based on the RS-232D terminal ready signal ER from the data terminal 37 and the transmission data SD, and sending the control data to the ping-pong transmission circuit 55 as D-channel upstream data D-IN.

FIG. 4 shows a detailed configuration of the data communication control microcomputer 59.

This microcomputer 59 includes a ping-pong transmission circuit 55.
The D-channel receiving unit 77 receives the D-channel downstream data D-OUT from the D-channel receiving unit 77, and sends the destination address included in the received data to the address analyzing unit 79. The address analysis unit 79 opens the gate 81 when the transmission destination address is the address of the data communication control microcomputer 59, and closes the gate 81 when the transmission destination address is the address of the telephone control microcomputer 57. When the gate 81 opens, the D-channel downlink data D-
IN is sent to the data analysis unit 83. According to the data analysis result in the data analysis unit 83, the CI control unit 85 controls the RS-232D called display signal CI, the DR control unit 87 controls the data set ready signal DR, and the data control unit 89 outputs control data, or a mode selection signal for determining a command receiving mode or a communication mode is switched. The mode selection signal is set at a low level in the communication mode and at a high level in the command reception mode, and is applied to the gate 95 through the inverter 91. Therefore, only in the command receiving mode, the gate 95 is opened, and the control data from the data control unit 89 is sent to the data terminal 37 as the RS-232D reception data RD.

The data monitoring unit 97 transmits the transmission data SD from the data terminal 37.
Is received through the gate 93 and analyzed, and the result is sent to the data creation unit 99. The data monitoring unit 97 receives the mode selection signal, and the type of data to be monitored differs between the command receiving mode and the communication mode as described later.
In the communication mode, when the data monitoring unit 97 receives the special data, the data monitoring unit 97 notifies the data analysis unit 127 of the reception, whereby the data analysis unit 127 switches the mode selection signal from the communication mode to the command mode.

The ER monitor 101 monitors the RS-232D terminal ready signal ER, and sends data indicating whether the data terminal 37 is ready to the data generator 99. The data creation unit 99 creates D channel data to be sent to the main device 1 according to the received data, and this D channel data is given to the gate 103. The gate 103 is opened by the control of the telephone control microcomputer 57 only while the telephone control microcomputer 57 does not transmit control data. When the gate 103 is open, the D channel data created by the data creation unit 99 is
A ping-pong transmission circuit which is sent to the channel transmission unit 105 and passes through the selector 63 as D-channel uplink data D-IN.
Sent to 55.

The automatic transmission / reception procedure uses the transmission data SD and the reception data RD to transmit control data called commands such as “outgoing”, “incoming”, “answer”, “connection”, “dial signal”, “disconnect request”, “end call” to the data terminal. 37 and data interface unit
This is a procedure for transmitting and receiving between the 35 parties, thereby proceeding with call connection and recovery processing. The data interface unit 35 is in the command receiving mode during standby, so that the data communication control microcomputer 59 monitors and controls the command. When the call connection process proceeds, the data interface unit 35 changes from the command receiving mode to the communication mode. After temporarily transiting to the communication mode, the data communication control microcomputer 59 monitors only the "disconnect request" and "end" commands, and upon receiving these commands, returns to the command receiving mode. The automatic transmission / reception procedure includes the CCITT recommendation V.25bis procedure.

FIG. 5 shows the configuration of the data interface unit 31 for connecting the RS-232D interface 47 of the modem 43 to the digital telephone interface unit 17 of the main unit 1.

The data interface unit 31 has a configuration similar to the data interface unit 35 for the data terminal described with reference to FIG. 2, but the main difference is that the latter is set to the modem mode for the data terminal 37. ,
The former is that the terminal mode is set for the modem 43. That is, the direction of the signal line of the RS-232D interface is reversed. Further, since the data interface unit 31 is not built in the telephone, the B1 channel for voice data transmission is not used, and there is no telephone control microcomputer, and the telephone control and data communication control are not provided. There is no selector for selecting uplink control data.

FIG. 6 shows the configuration of the digital telephone interface unit 13 in the main device 1 for connecting the digital telephone 27. The digital telephone interface unit 17 for connecting the data interface unit 31 has the same configuration.

The interface unit 13 is for example provided with eight ping-pong transmission circuit 149 ₁ to 149 _8, each connected to each of the data interface unit 35 of 8 phones 27 via the data transformer 151 for digital transmission, and this Ping-pong transmission is performed using a time-division channel of the 2B + D format. This ping-pong transmission circuit 149 is a ping-pong transmission circuit 55 in the data interface unit 35 shown in FIG.
However, the former operates in the slave mode, while the former operates in the master mode. That is,
The ping-pong transmission circuit 149 in the master mode has the initiative of the ping-pong transmission packet transmission.

The time slot assigner 153 receives the frame synchronization signal and the clock from the PCM highway 7, and notifies each ping-pong transmission circuit 149 of the timing of transmitting and receiving the B channel uplink and downlink data to and from the PCM highway 7. Each ping-pong transmission circuit 149 directly accesses the PCM highway 7 at a time designated by the time slot assigner 153 to transmit and receive upstream and downstream data at a speed of 2.048 Mbps.

The control data communication microcomputer 155 is responsible for monitoring D-channel data (control data) transmitted and received by each ping-pong transmission circuit 149 and communicating the control data with the control unit 3 through the data highway 5.

FIG. 7 shows the configuration of the standard telephone interface unit 21 to which the MODEM 43 is connected.

The paging signal transmission circuit 251 is a circuit for transmitting the paging signal (16 Hz AC signal) supplied from the paging signal generation source 253 to the MODEM 43. DC power supply circuit 255 is MODEM43
Is a circuit for supplying a specified DC voltage to the DC power supply, inverting its polarity, and detecting the opening and closing of the DC loop. The dial detection unit 257 is a circuit that detects a dial pulse.

The codec 259 performs A / D and D / A conversion of an audio signal, and transmits and receives audio data to and from the PCM highway 7 at a time designated by the time slot assigner 261.

The control data communication microcomputer 263 controls sending / stopping of a calling signal, monitoring of DC loop opening / closing, control of polarity inversion, monitoring of a dial pulse detection result, and control data communication with the control unit 3 through the data highway 5. It communicates.

One standard telephone interface unit 21 includes, for example, eight sets of a call signal transmitting unit 25, a DC power supply circuit 255, a dial detecting unit 257, and a codec 259, and up to eight MODEMs 43 can be connected.

FIG. 8 shows the configuration of the office line interface unit 11 for connecting the office line 25.

The interface circuit 237 includes a call signal detection circuit 239, a polarity inversion detection circuit 241 and a DC loop circuit 243, and is connected to the office line 25 of the public telephone network, detects a call signal from the office line 25, and inverts the polarity of the office line 25. , Closing / opening of a DC loop, and transmission of a dial pulse to an office line. Codec
Reference numeral 245 is for performing A / D and D / A conversion of the audio signal. The DC loop circuit 243 closes the DC loop of the station line 25, so that it is AC-coupled to the station line 25. For example, four sets of the interface circuit 237 and the codec 245 are mounted in one office line interface unit 11.

The time slot assigner 247 determines the timing at which each codec 245 transmits / receives audio data to / from the PCM highway 7 based on a predetermined time slot address for each codec, a frame synchronization signal from the PCM highway, and a clock. Notify 245. Each codec 245 transmits and receives audio data to and from the PCM highway 7 at a time designated by the time slot assigner 247.

The control data communication microcomputer 249 monitors the detection signals of the call signal detection circuit 239 and the polarity inversion circuit 241, controls the DC loop circuit 243, and detects the call signal with the control unit 3 through the control data highway 5.
It transmits and receives control data related to polarity inversion detection, opening and closing of a DC loop, transmission of a dial pulse, and the like.

FIG. 9 shows the structure of a part of the microcomputer 49 relating to call processing when receiving a call using the dial-in service from the office line 25. When receiving the dial-in service, a communication sequence performed between the central office line interface unit 11 and the local office 25 is defined by the network. The sequence of this communication is shown in FIG.

Prior to the description of FIG. 9, the sequence of FIG. 10 will be briefly described. At the time of an incoming call, the polarity of the office line is inverted from the office line 25 to the office line interface unit 11, and then a call signal is sequentially input. Thereafter, when the office line interface unit 11 sends a primary response signal to the office line 25, an extension designation signal (1- to 4-digit MF signal indicating an extension number) is sent from the office line 25. Thereafter, the line interface unit 11 changes the line 25
Sending the extension designation reception signal (DC loop break) and then the secondary response signal (DC loop closing) to the telephone (data communication)
Is started.

Next, the microcomputer 49 will be described with reference to FIG.

The receiving unit 281 receives control data from various interface units in the main unit via the data highway 5 and analyzes the control data.

The microcomputer 49 has a terminal speed and busy table 285 and a MODEM speed and busy table 313. The terminal speed and busy table 285 includes the extension numbers (200, 201, etc.), data speeds (1200 bps, 2400 bps, etc.) of each data terminal 37 _{1 to} 37 _n , and whether or not busy is available (busy: 1, empty: 0: 0). ) Is described. MODEM rate and the busy table 313, each MODEM43 ₁ ~43 _j extension (300,3
01, etc.), data speed (1200 bps, 300 bps, etc.) and state (busy: 1, empty: 0).

When the data terminal 37 changes from the busy state to the empty state, a command of “connectable” is sent from the digital telephone interface unit 13 to the receiving unit 281. When this command is received, the table rewriting unit 283 writes “0” indicating an empty state in the corresponding extension number column of the terminal speed and busy table 285.

Also for the MODEM 43, when the state changes from the busy state to the standby state, a “connection permitted” command is input to the receiving unit 281 from the data interface unit 31 connected to the MODEM 43. Then, the table rewriting unit 283 writes “0” indicating an empty state to the MODEM speed and busy table 313.

Predetermined specific office line for data communication, for example, polarity inversion in office line interface unit 11 ₁ to 25 _1, followed by a call signal arrives, the receiving unit 281 commands the office line interface unit 11 ₁ of the "incoming" Sent to Then, a time switch control unit 317 forms a communication path between the MF signal receiver 53 of the time switching circuit 5 is controlled to office line interface unit 11 ₁ and the control unit 3 a.
At the same time, command sending unit 319 is commanded office line interface unit 11 ₁ is sent in a primary response signal to the office line 25 _1.

Thereafter, the extension specifying signal arrives in the form of MF signals from the office line 25 _1, the extension specifying signal is analyzed is received in MF receiver 53, as a result, data of the designated extension number
It is provided from the MF receiver 53 to the extension number receiving unit 321 and stored in the register 323. The stored extension number is analyzed by the extension number analysis unit 325 and notified to the terminal / MODEM selection 291.

Terminal · MODEM selecting section 291 refers to the terminal continuously and busy table 285, data terminal having the extension number reported from the extension analyzer (hereinafter, referred to as selected data terminals), the state of the example 37 ₁ To check. If this selected data terminal 37 ₁ of the state of free, terminal · MODEM
Next, the selecting unit 291 refers to the MODEM busy table 313 and selects _one of the MODEMs in the idle state from the MODEM group having the same data rate as the selected terminal 371 (the selected MODEM).
ODEM as), selecting for example 43 _1. And terminal M
ODEM selection unit 291, and selected terminal 37 ₁ selected MODE
The M43 ₁ extension notifies the command sending unit 327, and a time switch controller 329. As a result, the command sending unit 3
27 sends to MODEM43 selected commands respectively ₁ and selected data terminal 37 ₁ connected data interface unit 31 ₁ and 35 ₁ of the "MODEM connection", a time switch control unit 329 controls the time switch circuit 51 and to connected MODEM43 ₁ it has been between data terminal 37 ₁ selection and selection. Furthermore, the table rewriting section 283, the selected status field of the terminal 37 ₁ and selected MODEM43 ₁ terminal busy table 285 and MODEM in busy table 313, and writes "1" indicating the busy state.

After completion of these operations, the command transmitting unit 333, the standard telephone interface unit 21 MODEM43 ₁ is selected connected sends a "call signal" command, and the office line interface unit 11 of the "extension specified reception completion" Send a command.

Thereafter, when the data terminal 37 ₁ selected to respond to the call, "response" command is input to the receiving unit 281 from the standard telephone interface unit 21. Then, MODEM43 ₁ which ordered閉結(delivery of a secondary response signal) of the DC loop command sending unit 335 to the office line interface unit 11 _1, and a time switch controller 337 is selected by controlling the time switch circuit 51 and connecting the station line 25 _1. Thus communication path for data communication between selected data terminal 37 ₁ and the calling-side data device is formed.

If the data terminal 37 ₁ to terminate the data communication,
A command of “loop release” is input from the standard telephone interface unit 21 to the receiving unit 281. Then, the command sending unit 339 sends the "loop open" command to the office line interface unit 11 _1, and "disconnection instruction"
Is sent to the data interface units 31 ₁ and 35 ₁ . At the same time, a time switch control unit 341 controls the time switch circuit 51, MODEM43 ₁ and station line 25 ₁ and between MODEM
43 ₁ and to disconnect both communication path between the data terminal 37 _1.

Next, referring to FIG. 11, a specific station line 25 for data communication is used.
The operation of the system when there is an incoming call using the dial service from ₁ will be described.

The data interface unit 35 in each digital telephone 27 constantly monitors the ready state of the data terminal 37 during standby, and when the terminal ready signal ER is turned on, this is detected by the data communication control microcomputer 59,
The data set ready signal DR for the data terminal 37 is turned on, and “connection is possible” to the control unit 3 in the main device.
Send a command. In the main device 1, when the microcomputer 49 in the control unit 3 receives this "connection possible" command, "0" is written in the terminal speed and the corresponding terminal column of the busy table 285. Similarly, the ready state of both the MODEM 43 and the data interface unit 31 is monitored. During standby, the data interface unit 31 always turns on the terminal ready signal ER. Then, when the MODEM 43 turns on the data set ready signal DR, the microcomputer 109 in the data interface unit 31 detects this and sends a “connection permitted” command to the control unit 3 in the main device. Upon receiving this command, the microcomputer 49 in the main unit writes the MODEM speed and the busy table "0". When the polarity inversion and calling signal arrives at the main device ₁ from the data communication specific station 251, the microcomputer 249 in the office line interface unit 11 recognizes this as a dial-in incoming signal, and transmits an "incoming" command to the control data. The signal is sent to the control unit 3 in the main unit through the highway 5. When the microcomputer 49 in the control unit 3 receives the "incoming" command, it controls the time switch circuit 51 to control the line interface unit.
11 is replaced with data between time slots allocated to the time slot and MF receiver 53 allocated to _1, to connect between ₁ and MF receiver 53, that station line 25. And further controls the office line interface unit 11 computers 249 _1, are sent to primary response signal to the office line 25 _1. Then, 1-4 digit extension specifying signal in the form of MF signal from the office line 25 ₁ arrives, is input to the MF receiver 53.

The MF receiver 53 analyzes the received MF signal and notifies the microcomputer 49 of the specified extension number as a result. When the microcomputer 49 receives the extension number, the data terminal selected by the extension number,
For example examined 37 ₁ state by referring to the table 285, reads out the selected data rate of the terminal 37 ₁ if the result empty. Then, the microcomputer 49 refers to the modem speed and the busy table 313, from in MODEM group with the same data rate as the data terminal 37 ₁ selection, selects one of the MODEM example 43 ₁ in empty state .
Thereafter, selected data terminals 37 ₁ and selected MODEM
Data interface unit 31 ₁ to which 43 ₁ is connected
35 Send “MODEM connection” command to ₁ . The writing Bijiibitto "1" to the selected status field of the terminal 37 ₁ and MODEM431 of both tables 285,313. Furthermore, the selected replacement between time slots allocated to MODEM43 ₁ which is selected and the selected data terminal 37 time slots allocated to ₁ for the time switch circuit 51, i.e. the selected data terminal 37 ₁ Command connection between MODEM43 ₁

The data interface unit 35 _1, if the microcomputer 59 receives the "MODEM connection" command, sets the communication mode by controlling the selector 65 and 67. Similarly, the communication mode even data interface unit 31 ₁ is set.

Thus, MODEM43 ₁ RS-232D interface 47 ₁
In the path of the data interface unit 31 ₁ digital telephone interface unit 17PCM highway 7 digital telephone interface unit 13 _one data interface unit 35 ₁ RS-232D interface 39 ₁ Data terminal 37 _1, MODEM43 ₁ and data terminal
A data communication path between 37 ₁ is formed.

If the above processing is completed, the main unit in the microcomputer 49 to transmit a call signal for controlling a computer 263 in the standard telephone interface unit 21 to the MODEM43 _1. Further office line interface unit
11 ₁ is controlled to transmit an extension designation reception completion signal (DC loop break) to the station line 25 ₁ .

MODEM43 ₁ is RS-232D if the above call signal is received.
As for receiving data RD (from MODEM43 ₁ to data interface unit 31 ₁₎ sends a "call" command.
This command is sent to the data terminal via the data communication path described above.
37 Received on ₁ If the data terminal 37 receives this command, the data terminal 37 receives the "incoming response" as the RS-232D transmission data SD.
Send a command and wait for a "connect" command to arrive.

MODEM43 ₁ is When receiving the "incoming response" command from the data terminal 37 _1, with responds by closing the DC loop, it transmits a "connection" command as received data RD.

The main device of the computer 49 is the central office line interface unit if recognized DC loop closure according MODEM43 ₁
11 ₁ is controlled to transmit a secondary response signal (closed DC loop) to the station line 25 ₁ . In addition, a time switch circuit
Exchange between the allocated time slots to the time slot and the standard telephone interface unit 21 assigned to the central office line interface unit 11 ₁ for 51 instructs the speech path formation between clogging station lines 25 ₁ and MODEM43 _1.

Thus communication between a calling-side data device and the data terminal 37 ₁ is started via the office line 25 _1.

〔The invention's effect〕

As described above, according to the present invention, when an incoming call is received from the central office to the system, the data terminal selected by the extension designation signal of the dial-in service and the attribute corresponding thereto are provided.
To select MODEM and first form a data communication path between the terminal and MODEM so that the two are directly connected, control and analysis of control commands associated with outgoing / incoming calls are handled by the data terminal. And MODEM, thereby reducing the load on the data interface unit and the central processing unit in the system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of a key telephone system according to the present invention. FIG. 2 is a block diagram showing a configuration of a data interface unit (DIU) for a data terminal in FIG. 3 is a block diagram showing the configuration of the ping-pong transmission circuit in FIG. 2, FIG. 4 is a block diagram of a data communication control microcomputer 59 in FIG. 2, and FIG. 5 is a MODEM in FIG. FIG. 6 is a block diagram showing the configuration of a digital telephone interface unit in FIG. 1, and FIG. 7 is a standard telephone interface unit (STU) in FIG. Block diagram showing the configuration of FIG.
FIG. 9 is a block diagram showing a configuration of a central office interface unit (COU) in FIG. 1, FIG. 9 is a block diagram showing a main part of a microcomputer of a control unit in FIG. 1, and FIG. Communication sequence chart between the office line and the system when receiving service.
It is a sequence diagram explaining operation | movement of the system of a figure. 1 Main unit (KSU), 3 Control unit, 11 Central office interface unit (COU), 13, 17 Digital telephone interface unit, 21 Standard telephone interface unit (STU), 27 Digital telephone, 31 ... Data interface unit (for MODEM), 35 ... Interface unit (for data terminal), 37 ... Data terminal (DTE), 43 ... MODEM, 49 ... Microcomputer, 51 ... Time switch circuit, 53…
MF signal receiver 281 Receiver 283 Table rewriter 285 Terminal speed and busy table 291
Terminal / MODEM selection unit, 313: MODEM speed and busy table, 317, 329, 337, 341: Time switch control unit, 31
9,327,333,335,339... Command transmission unit, 321... Extension number reception unit, 323... Register, 325.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H04M 3/00 H04M 11/00-11/10 H04Q 3/58

Claims (2)

(57) [Claims] An extension is connected to a central office line that can provide a dial-in service, and a plurality of data terminals are connected to an extension.
More than one MODEMs are pooled, and these MODEMs have a built-in network controller and have a function of performing an automatic call originating / terminating procedure for the data terminal.
In a key telephone system including an exchange unit for forming and disconnecting a communication path between DEMs, a terminal attribute storage unit for storing each attribute of the data terminal, and a MODEM attribute storage unit for storing each attribute of the MODEM. A terminal selecting means for selecting one data terminal based on an extension designation signal of a dial-in service given from the office line when receiving an incoming call from the office line; and Recognize the attribute of the data terminal and select one MODEM having an attribute that matches this attribute by referring to the MODEM attribute recognizing means.
MODEM selection means, controlling the exchange means to form a communication path between the selected data terminal and the selected MODEM, thereby as if there is between the selected data terminal and the selected MODEM. First exchange control means for making a direct connection, MODEM call means for giving a call signal to the selected MODEM after forming a communication path between the selected data terminal and the selected MODEM, In response to the response of the selected MODEM to a call signal, controlling the exchange means to select the selected MODEM
Forming a communication path between M and said office line, whereby said selected MODEM between said selected data terminal and said office line.
And a second exchange control means for forming a communication path through the key telephone system. 2. The system according to claim 1, wherein the terminal attribute storage means further stores a status of busy or empty of each data terminal, and the MODEM attribute storage means stores a busy of each MODEM. Whether the state of the selected data terminal connected to the terminal attribute storage means is empty, and the MODEM selection means is stored in the MODEM attribute storage means. A button for selecting one MODEM having an attribute that matches the selected data terminal from among the empty MODEMs only when there is at least one MODEM whose state is empty. Phone system.