JPH0537538A - Isdn terminal connection system - Google Patents

Abstract

PURPOSE:To extend the connection distance from a PBX connecting to an ISD network to an ISDN terminal. CONSTITUTION:The system consists of a PBX3 connecting to an ISDN network, a synchronizing loop LAN 5 and an ISDN terminal equipment 4, and the ISDN terminal equipment 4 connects to the PBX3 via the LAN 5. Then a TE mode interface 1 is provided between the PBX 3 and the LAN 5 and an NT mode interface 2 is provided between the ISDN terminal equipment 4 and the LAN 5. Then a point S interface of the ISDN (network - terminal interface) is formed by connecting the PBX3 and the ISDN terminal equipment 4 via the LAN 5 in this way. Furthermore, the LAN 5 is provided with the TE mode interface 1 as if it were the ISDN terminal equipment 4 when viewing from the PBX3 and with the NT mode interface 2 as if it were the PBX3 when viewing from the ISDN terminal equipment 4, and a transparent transmission line is formed, in which the presence of the LAN 5 is not notified by the PBX3 and the ISDN terminal equipment 4. Since the reproduction relay in the waveform transmission is implemented in the interfaces 1, 2, the connection distance between the PBX and the ISDN terminal equipment is extended more than that of a conventional system.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to ISDN (Integrated Services Digi
tal network) terminal connection system, and more particularly to a system for connecting an ISDN terminal to a PBX (Private Branch Exchange) connected to an ISDN network.

[0002]

2. Description of the Related Art Generally, a PBX is connected to an ISDN network, and an ISDN terminal is connected to the PBX to realize various communication services.

However, there are problems in waveform transmission and propagation delay. Conventionally, PBX and ISDN connected to it have been used.
The distance from the terminal is point-to-point (point-to-point method)
1 [Km], point-multipoint (branch method)
There was a drawback that there was a limit of about 500 [m].

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and an object thereof is to provide an ISDN terminal connection system capable of extending the distance between a PBX and an ISDN terminal. That is.

[0005]

The ISDN terminal connection system according to the present invention comprises:
A system for connecting an ISDN terminal to a PBX connected to an ISDN network, characterized in that the ISDN terminal is connected to the PBX via a LAN.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of an ISDN terminal connection system according to the present invention. In the figure, an ISDN terminal connection system according to an embodiment of the present invention is
PBX 3 connected to ISDN network and synchronous loop LAN (Lo
cal area network) 5 and an ISDN terminal 4, and the ISDN terminal 4 is connected to the PBX 3 via a LAN. And, between PBX 3 and LAN 5, TE
Mode interface 1 is provided, ISDN terminal 4 and LAN
An NT mode interface 2 is provided between the terminal 5 and the terminal 5.

Thus, the PBX 3 and ISDN are connected via the LAN 5.
By connecting to the terminal 4, an ISDN S point interface (network-terminal interface) is configured. Furthermore, the LAN 5 is provided with a TE mode interface 1 that looks like an ISDN terminal from the PBX and an NT mode interface 2 that looks like a PBX from the ISDN terminal. LAN on the terminal
A transparent transmission line that does not make people aware of the existence of

At this time, the PBX 3 is subordinately synchronized with the clock of the ISDN network, and the LAN 5 is also subordinately synchronized with the PBX 3, whereby subordinate synchronization is realized between the ISDN network and the LAN 5.

In each of the interfaces 1 and 2, the PBX is regenerated and relayed in the waveform transmission.
-It is possible to extend the connection distance between ISDN terminals as compared to the past.

Next, TE mode interfaces 1 and N
A configuration example of the T mode interface 2 will be described.

FIG. 4 is a block diagram showing an internal configuration example of the TE mode interface 1. In the figure, a TE mode interface 1 uses a well-known I430 interface as an interface between the PBX 3 and the LAN 5 in FIG. The inside thereof includes a receiver 10, a decoder 11, a synchronization detection circuit 12 for detecting a synchronization signal in frame data, a clock for extracting a clock from data based on the detected synchronization signal, and a clock for detecting a frame bit. The extraction / frame detection circuit 13 is included.

Further, the TE mode interface 1 converts the elastic stores 14 and 16 for buffering and the serial data from the elastic store 14 into parallel data and sends the parallel data to the loop, and the parallel data from the loop to the serial data. Conversion circuit 15 for converting to
And a 2-bit offset circuit 17 for adjusting 2-bit offset according to the ISDN standard, a coder 18,
The driver 19 is included.

In such a configuration, after the data from the PBX side is received by the receiver 10, it is decoded by the decoder 11 and input to the elastic store 14. Then, the serial data from the elastic store 14 is converted into parallel data by the conversion circuit 15 and sent to the loop. In this case, the loop is a transmission line for electric signals or optical signals.

The parallel data from the loop is converted into serial data by the conversion circuit 15 and input to the elastic store 16. Then, the output data of the elastic store 16 is encoded by the coder 18 after being offset-adjusted, and is encoded by the driver 19 into the PBX.
Sent to the side.

FIG. 5 is a block diagram showing an internal configuration example of the NT mode interface 2. In the figure, the NT mode interface 1 uses a well-known I430 interface as an interface between the LAN 5 and the ISDN terminal 4 in FIG. The inside is the receiver 20,
A decoder 21, a sync detection circuit 22 for detecting a sync signal in frame data, and a clock extraction / frame detection circuit 23 for extracting a clock from data and detecting a frame bit based on the detected sync signal. It is configured to include.

Also, the NT mode interface 2 converts the elastic store 24 for buffering, serial data from the elastic store 24 into parallel data and sends it to the loop, and also converts parallel data from the loop into serial data. The conversion circuit 25, the coder 28, and the driver 29 are included. Furthermore, the NT mode interface 2 inserts an echo bit (E bit) in the serial data from the conversion circuit in response to the D bit detecting means 26 for detecting the control bit (D bit) and the detection of this D bit. The E-bit insertion circuit 27 is included. A pseudo response is made to the ISDN terminal 4 by inserting the E bit. If this pseudo response is not made, the original return of E bit from the PBX side will be delayed due to the existence of LAN and the prescribed response time limit cannot be satisfied.

In such a structure, after the data from the ISDN terminal 4 side is received by the receiver 20, it is decoded by the decoder 21 and D bit detection is performed, and is input to the elastic store 24. Then, the serial data from the elastic store 24 is converted into parallel data by the conversion circuit 25 and sent to the loop.
Further, the parallel data from the loop is converted into serial data by the conversion circuit 25, E bits are inserted, coded by the coder 28 and ISDN by the driver 29.
It is sent to the terminal 4 side. If necessary, elastic stores may be provided before and after the E-bit insertion circuit 27.

Next, an example of a frame format of data exchanged between the above interfaces will be described with reference to FIG.

FIG. 3 is a schematic block diagram of a frame format "2B + D" used in the well-known I430 interface. F in the figure indicates a frame bit. Then, D is the above-mentioned D bit, and the echo bit E is inserted into the frame in response to the D bit detection. This bit insertion realizes 192 [kb / s] transmission. As described above, the 2-bit offset is made in the portion indicated by A in the figure. It should be noted that the other parts in the frame include data, control data, and the like.

Here, "B" of "2B + D" is 64 [kb
/ s] data channel, “D” means a control data channel of 16 [kb / s], and the control data channel is added to the two data channels.

The frame configured as described above is sent from the ISDN terminal to the PBX via the LAN. The monitoring timer value until the PBX returns an echo bit in response to a call from the terminal is about 30 [μs]. Therefore, the echo bit is inserted as a pseudo response as described above.

The above TE mode interfaces 1 and N
An example of system operation using the T-mode interface 2 will be described with reference to FIG. FIG. 2 is a sequence diagram of data transmitted / received via each interface of FIGS. 4 and 5 and LAN.

Signals exchanged between the PBX 3 and the ISDN terminal 4 via the LAN 5 include four types of signals, INFO1 to INFO4. First, INFO1 is a calling signal from the terminal 4 to the PBX 3, which is a predetermined 8-bit continuous pattern. INFO2
Is a response signal of 192 [kb / s] from the PBX 3 to the terminal 4. INFO3 is 192 that synchronization has been established from the terminal 4 to the PBX 3.
The data is [kb / s]. INFO4 is the data of 192 [kb / s] from the PBX 3 to the terminal 4 for which synchronization is established.

INFO0 indicates an idle state (no signal).

In FIG. 2, the INFO0 signal is output from the ISDN terminal 4 when the ISDN terminal 4 is not making a call yet, and is transmitted to the PBX 3 via the NT mode interface 2 and the TE mode interface 1 of the LAN 5. To be done.
Here, when a call is made, the ISDN terminal 4 outputs the INFO1 signal, which is transmitted to the PBX 3 as described above.

In PBX 3, as a response to the INFO1 signal
The INFO2 signal is returned to the ISDN terminal 4. At this point PBX 3
The synchronization between the ISDN terminal 4 and the ISDN terminal 4 is established, and then (2B +
D) 192 [kb / s] synchronous data INFO3 and IN
FO4 data is exchanged. At this time, in the NT mode interface 2, as described above, in the frame format shown in FIG. 3, only the E bit (echo bit), which has a limited time until response, is sent to the PBX 3.
The return limitation (pseudo response) is performed without waiting for the response from. The original E bit is overwritten on the conversion circuit and disappears.

That is, according to the present invention, it is possible to realize the ISDN S-point interface using LAN while solving the problem of echo bit time limitation. In addition, the loop type
The configuration is not limited to LAN, and star-type or bus-type LAN can be used in the same way.

[0029]

As described above, the present invention realizes the SDN interface of ISDN by using LAN,
There is an effect that an ISDN terminal existing in a place away from the ISDN network can be accommodated in the PBX, and the connection distance between the PBX and the ISDN terminal can be extended.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an ISDN terminal connection system according to an embodiment of the present invention.

FIG. 2 is an operation sequence diagram of the system of FIG.

3 is an example of a frame format of transmission / reception data in the system of FIG.

FIG. 4 is a block diagram showing a configuration example of a TE mode interface in FIG.

5 is a block diagram showing a configuration example of an NT mode interface in FIG.

[Explanation of symbols] 1 TE mode interface 2 NT mode interface 3 PBX 4 ISDN terminal 5 LAN

Claims (1)

What is claimed is: 1. A system for connecting an ISDN terminal to a PBX connected to an ISDN network, wherein the ISDN terminal is connected to the PBX via a LAN. Connection system.