JPS6235745A - Leased line signal transmission system - Google Patents

Abstract

PURPOSE:To prevent call processing ability from being threatened by the transmission of a control signal by controlling the logical value of the lest significant digit bit of a PCM code transmitted through a leased line. CONSTITUTION:When a subscriber line 5 makes a response, a calling control circuit 632 which receives the report stops driving a calling signal sending-out circuit 682 and a monitor and control circuit 602 detects the off-hook state of the subscriber line 5 and sets the least significant digit bit of the PCM code sent out to the leased line to logic '1'. A subscriber circuit 6' extracts the least significant digit bit of the PCM code arriving from the leased line and transmits it to a calling control circuit 631 to detect the change of the least significant digit bit transmitted from a branch circuit 621 from logic '0' to logic '1', but the calling of a subscriber line 4 is already reported from a monitor and control circuit 601, so a call signal sending-out circuit 681 is never driven. The subscriber lines 4 and 5 are engaged with each other through the leased line thereafter.

Description

[Detailed Description of the Invention] [Summary] In a subscriber circuit that is semi-permanently connected by a leased line set within a digital switching network, the By controlling the logical value of the least significant bit of the transmitted PCM code, call processing capacity is prevented from being compressed by the transmission of control signals.

[Industrial application field]

The present invention relates to improvements in a leased line signal transmission system for transmitting signals via a leased line set within a digital switching network.

Even in digital switching networks, subscriber lines that frequently communicate are semi-permanently connected by dedicated lines.

In order to transmit calling signals and other control signals between subscriber lines connected by such dedicated lines, it is desirable that the call processing capacity of the digital switching network is not strained as much as possible.

[Conventional technology]

FIG. 3 is a diagram showing an example of a conventional leased line signal transmission system, and FIG. 4 is a diagram showing an example of the PCM code in FIG. 3.

In FIG. 3, subscriber circuits (SLC) 6 and 7, communication network (NW) 8 and 9. Digital terminal (D
T) A semi-permanent communication path, ie, a dedicated line, is set up via the terminals 10 and 11 and the digital trunk line 12. The voice information transmitted by subscriber lines 4 and 5 is converted by subscriber circuits 6 and 7 into an 8-bit PCM code as shown in FIG. The signal is then transmitted to the opposite subscriber lines 5 and 4 after being inversely converted into an analog format.

If the subscriber line 4 now makes a call, the subscriber circuit 6 will call the subscriber line 4.
off-hook, and transmits a calling signal to the central control unit (CC) 13 via the communication path network 8. Central control device 1
3 transmits the calling signal of the subscriber line 4 to the digital exchange 3 via the communication path network 8 and the digital terminal 10, and via the control signal transmission channel of the digital trunk line 12.

In the digital exchange 3, the central controller 14 transmits the calling signal of the subscriber line 4 arriving from the control signal transmission channel of the digital middle line 12 to the digital terminal 1.
1 and the communication network 9, and instructs the subscriber circuit 7 via the communication network 9 to send out a paging signal. Sends a call signal to the other party.

When the subscriber line 5 responds, the subscriber circuit 7 stops sending the ringing signal to the subscriber line 5. Thereafter, the subscriber lines 4 and 5 communicate via the dedicated line.

[Problem that the invention seeks to solve]

As is clear from the above explanation, in the conventional leased line signal transmission system, all control signals such as the calling signal for the subscriber line 4 and the paging signal for the subscriber line 5 are transmitted from the central point of the attached digital exchanges 2 and 3. The signals are transmitted by control devices 13 and 14.

Since the central control units 13 and 14 are in charge of processing calls made to and received from the subscriber lines they accommodate, the transmission control of control signals between the subscriber lines 4 and 5 connected by the dedicated line as described above is controlled by the central controllers 13 and 14, respectively. This results in pressure on the call processing capacity of the digital exchange M41.

(Means for solving problems) FIG. 1 is a diagram showing the principle of the present invention.

In FIG. 1, subscriber circuits 6' and 7' are semi-permanently connected by a dedicated line set up in the digital switching network I.
The PC monitors the on-hook and off-hook of the accommodated subscriber line 4.5 and sends it to the dedicated line based on the monitoring results.
A supervisory control means 101.102 and an insertion means 201.202 which control the logical value of the least significant bit of the M code extract the least significant bit of the PCM code arriving from the leased line and join based on the logical value of the least significant bit. Branching means 301, 302 and a calling control circuit 401, 402 are provided for controlling sending of a calling signal to the subscriber line.

[Effect]

That is, according to the present invention, control signals such as calling signals are sent and received between subscriber circuits via dedicated lines set up within the digital exchange network, and do not go through the central control device of the affiliated digital exchange. , there is no risk of putting pressure on the call processing capacity of the digital switching network.

〔Example〕

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

FIG. 2 is a diagram showing a dedicated line signal transmission system according to an embodiment of the present invention. Note that the same reference numerals indicate the same objects throughout the figures. In addition, the PCM code transmitted on the dedicated line is
As shown in the figure.

In FIG. 2, the central control units 13 and 14 of the digital exchanges 2 and 3 are omitted. Further, the subscriber circuits 6' and 7' are connected by a dedicated line set up via communication network 8 and 9, digital terminals 10 and 11, and digital trunk line 12,
Supervisory control means 101, 102 and insertion means 2, respectively.
As 01.202, the monitoring control circuit 601.602 and the insertion circuit 611.612 are connected to the branching circuit 621 as the branching means 301, 302 and the call control means 401.402.
．． 622 and call control circuits 631 and 632 are provided. In addition, power supply circuit 641.642, two-wire four-wire conversion circuit 651.652, encoder 661.662, decoder 67
1.672 and the calling signal sending circuit 681.682,
The functions provided by conventional subscriber circuits are shared.

In FIG. 2, supervisory control circuits 601 and 602 monitor the on-footer and off-hook of subscriber lines 4 and 5 via power supply circuits 641 and 642, and when subscriber lines 4 and 5 are in the on-hook state, the circuit 61
1 and 612, encoders 661 and 662
The least significant bit of the PCM code sent from
D) is set to logic "0".

In such a state, when the subscriber line 4 makes a call, the subscriber circuit 6
The supervisory control circuit 601 in the inside detects off-hook of the subscriber line 4, notifies the call control circuit 631 of the call origination of the subscriber line 4, and controls the insertion circuit 611 to detect the PCM transmitted from the encoder 661. The least significant bit of the code (Figure 4 LSD
> is set to logic “1”. The PCM code is transmitted to the subscriber circuit 7° via the dedicated line.

In the subscriber circuit 7'', the branch circuit 622 detects the least significant bit of the PCM code arriving from the leased line (LSD in FIG. 4).
is extracted and transmitted to the call control circuit 632. When the paging control circuit 632 detects that the least significant bit (LSD in FIG. 4) transmitted from the branch circuit 622 changes from logic "0" to logic "1", it drives the paging signal sending circuit 682 and joins. A calling signal is sent to the personal line 5.

When subscriber line 5 responds, paging signal sending circuit 682 sends subscriber'f! to paging control circuit 632. Notify A5 of off-hook. The paging control circuit 632 that has received the notification stops driving the paging signal sending circuit 682. Thereafter, the supervisory control circuit 602 detects off-hook of the subscriber line 5, and sets the least significant bit (LSD in FIG. 4) of the PCM code sent to the leased line to logic "1", as in the subscriber circuit 6''. The PCM code is transmitted to the subscriber circuit 6'' via the dedicated line.

In the subscriber circuit 6', the branch circuit 621 receives the least significant bit of the PCM code arriving from the leased line (LSD in FIG. 4).
is extracted and transmitted to the call control circuit 631. The call control circuit 631 detects that the least significant bit (LSD in FIG. 4) transmitted from the branch circuit 621 changes from logic "0" to logic "1", but the 4, the calling signal sending circuit 681 is not driven.

Thereafter, subscriber lines 4 and 5 communicate with each other via the dedicated line.

As is clear from the above description, according to this embodiment, the call origination on the subscriber line 4 and the response on the subscriber line 5 are performed using the least significant bits of the PCM code (see FIG. 4) transmitted via the leased line. L.S.
D) between the subscriber circuits 6' and 7', and does not go through the central control equipment (not shown) of the associated digital exchanges 2 and 3, there is no risk of affecting the call processing capacity of the digital switching network 1. None.

Note that FIGS. 2 and 4 are only one embodiment of the present invention, and for example, the PCM code is not limited to an 8-bit structure, and many other modifications may be considered. In either case, the effects of the present invention remain the same. Also subscriber circuit 6
7' or the configuration of the digital switching network 1 is not limited to what is shown in the drawings, and many other modifications may be considered, but the effects of the present invention remain the same in either case.

〔Effect of the invention〕

As described above, according to the present invention, in the subscriber circuit, control signals such as calling signals are transmitted between the subscriber circuits via a dedicated line set within the digital switching network, and Since the call does not go through the central control unit, there is no risk of straining the call processing capacity of the digital switching network.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a diagram showing a leased line signal transmission system according to an embodiment of the present invention, and FIG. 3 is a diagram showing an example of a conventional leased line signal transmission system. , FIG. 4 is a diagram showing an example of the PCM code in FIG. 3. In the figure, 1 is a digital switching network, 2 and 3 are digital exchanges, 4 and 5 are subscriber lines, 6.7.6° and 7'' are subscriber circuits (SLC), and 8 and 9 are communication line networks. (NW), 10 and 11 are digital terminals (DT), 12 is a digital trunk line, 13 and 1
4 is a central control unit (CC), 101 and 102 are supervisory control means, 201 and 202 are insertion means, 301 and 302 are branch means, 401 and I02 are call control means, 601 and 602 are supervisory control circuits, 611 and 612 is an insertion circuit, 621 and 622 are branch circuits, 6
31 and 632 are call control circuits, 641 and 642
is a power supply circuit, 651 and 652 are two-wire and four-wire conversion circuits,
661 and 662 are encoders, 671 and 672 are decoders, and 681 and 682 are calling signal sending circuits. O〈A≦Sun/Moon Sword ni Kamane 11 Figure Q/23456 I Shiba Rairo Senffl Zoryo I Word Name I Europe Shipping Method m3 Figure]
This is an example of everyone's anger. 4 Figure

Claims (1)

[Claims] Subscriber circuits (6', 7') installed in the digital switching network (1) and semi-permanently connected by a dedicated line that transmits voice information using a PCM code composed of predetermined bits. , the subscriber line (4') accommodated in the subscriber circuit (6', 7')
, 5), and controls the logical value of the least significant bit of the PCM code sent to the dedicated line based on the monitoring result.
, 102) and insertion means (201, 202), extracting the least significant bit of the PCM code arriving from the dedicated line, and controlling the sending of a paging signal to the subscriber line based on the logical value of the least significant bit. Branching means (301
, 302) and a paging control circuit (401, 402).