JPS61127259A - Digital subscriber emergency calling system - Google Patents

Abstract

PURPOSE:To perform a call by using an analog telephone set when a subscriber line change-over circuit is actuated, by providing an analog telephone set which is connected through a subscriber line change-over circuit provided with a circuit terminal equipment as well as an analog subscriber circuit which is connected through a subscriber line change-over circuit provided with an exchange side subscriber circuit. CONSTITUTION:When an outgoing by means of a digital telephone set 61 and the like fail to start, the set 61 is on-hook and a subscriber line change-over circuit 54 (EMG) is changed over to the opposite side as shown on the figure by manual operation. A loop monitoring circuit 24 detects that a current loop up to the present has been cut and indicates a polarity inverting circuit 25 to change over a switch, once after informing a central control circuit 22 of occurrence of abnormality. Recently, the analog telephone set 7 is so hooked off, the loop circuit is completed again when voltage of a line 41 becomes minus and voltage of a line 42 becomes plus by an actuation of a polarity decision circuit 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a system in which an analog telephone is connected to a digital subscriber line via a switching circuit, and a call can be made via the digital line in an emergency.

[Prior Art] When performing digital communication using in-house digital equipment connected to a digital subscriber line, for example, when a telephone is taken off-hook, the situation is different from that of an analog system. In other words, in the analog system, the switching equipment's processing was simple, such as starting to send out a dial tone as soon as it detected that the current loop was completed. In the digital system, when off-hook is detected by some means, the equipment inside the home repeats data processing with the equipment on the exchange side via the digital line to confirm that the equipment is operational. It is then possible to make a call.

[Problems to be solved by the invention] In the above case, it is possible to make a call only after several processes have been completed, so if there is a slight error during the process, the process will stop there. There was a drawback that communication by the device could not be started.

[Means for solving the problems] The means adopted by the present invention to solve the above-mentioned problems are as follows:
A subscriber is accommodated in a digital subscriber line, a subscriber circuit on the exchange side is equipped with a power supply circuit and a loop monitoring circuit, a line termination device is equipped with a power reception circuit for receiving power supplied from the power supply circuit, and a digital, In the method of making calls using the subscriber line, the analog telephone is connected via the subscriber line switching circuit installed in the line termination equipment, and the subscriber line switching circuit is connected to the subscriber line switching circuit installed in the subscriber circuit on the exchange side. The analog telephone set is equipped with a connected analog subscriber circuit, and when the subscriber line switching circuit is operated, it is possible to make a call using the analog telephone set.

[Function] Since the analog telephone and the analog subscriber circuit are connected via the digital subscription-to-line switching circuit, even if communication becomes impossible due to a failure in the digital device,
A switching circuit switches connections and allows emergency calls to be made using an analog telephone.

[Example] The drawings are diagrams showing the configuration of an embodiment of the present invention.

1 is the exchange network, 2 is the digital subscriber circuit D
LC, 3 is an analog subscriber circuit SLC, 4 is a digital subscriber line, 5 is a line termination device NT, 61. 62=-
・ is a digital terminal device such as a telephone, a computer terminal, 7 is an analog telephone, 8 is various testing equipment in the office, 21
2 is a digital transmission section, 22 is a central control circuit, 23 is a power supply circuit, 24 is a loop monitoring circuit, 25 is a polarity inversion circuit, 2
6 is a subscriber line switching circuit trn on the subscriber circuit side, 51 is a digital transmission section, 52 is a power receiving circuit, 53 is a diode circuit D1, 54 is a subscriber line switching circuit EMG on the line termination device side, and 55 is a diode circuit D2. It shows.

To explain the operation with reference to the drawings, normally the analog telephone set 7 and the analog subscriber circuit 3 are in an inactive state.

A digital transmission unit 51 in the line termination unit 5 (NT) and a digital transmission unit 21 in the digital subscriber circuit 2 (DLC) are connected via the digital subscriber line 4. The power supply current from the power supply circuit 23 is passed through the diode circuit 53.
(Di), only the necessary minimum amount is always supplied to the power receiving circuit 5.
2, and voltage is applied to the digital transmission section 51 and the like. Therefore, the digital telephone 61 and the like can communicate with other devices via the digital subscriber line 4 and the exchange network 1 (NW) after some processing is required to start communication.

Next, if the digital telephone 61 or the like fails to initiate a call, the telephone 61 cannot make a call.

Therefore, the telephone 61 goes on-hook and the subscriber line switching circuit 54 (EMG) is manually switched to the side opposite to that shown in the figure.

For analog telephone 7, diode circuit 55 (D2
) is connected, the subscriber line 4 becomes the same as if it were disconnected. The loop monitoring circuit 24 detects that the previous current loop has been cut off, and notifies the central control circuit 22 of the occurrence of an abnormality. Since the central control circuit 22 cannot determine whether the fault is the disconnection of the subscriber line 4 or some other fault, -
The polarity inverting circuit 25 is instructed to change the switch. Since the analog telephone 7 is off-hook at this time, the loop circuit is completed again when the voltage on the line 41 becomes negative and the voltage on the line 42 becomes positive due to the operation of the polarity determining circuit 25. That is, the loop monitoring circuit 24 learns that the call is from the analog telephone 7 and notifies the central control circuit 22, and as a result, the subscriber line switching circuit 26 (of the subscriber circuit 2 (DLC) Ill)
trn) to the opposite position as shown.

Therefore, processing by the analog subscriber circuit 3 (SLC) is started, and an emergency call can be made with a predetermined party via the network 1 (NW).

At this time, the connection to the analog subscriber circuit 3 (SLC) may be made in multiple ways with switching lines from a plurality of digital subscriber circuits 2 (DLC). This is because only specific subscribers registered in advance or construction personnel can connect to the analog subscriber circuit 3 (SLC).

The relay contact of the subscriber line switching circuit 26 (trn) is restored when the subscriber circuit 3 (SLC) detects the on-hook of the calling telephone ta7.

Although the case where the analog telephone 7 and the digital telephone 61 are provided completely separately has been described above, in reality, an A/D converter is provided before the line of the analog telephone reaches the digital transmission section 51. A changeover switch is provided to enable branching from the telephone side of the D converter to the diode circuit 55, allowing the digital telephone to be shared with an analog telephone for emergency calls.

In addition, subscribers who can receive this service are for emergency use by important specified persons, but in-office testing equipment 8 is installed on the exchange side, and when new digital equipment is installed, it is used to communicate with station maintenance personnel etc. It can also be used to take.

[Effects of the Invention] As described above, according to the present invention, with a relatively simple configuration, it is possible to make an emergency call using an analog telephone when a digital subscriber's home is not functioning properly, which is practically effective.

[Brief explanation of drawings]

The drawings are process diagrams showing the configuration of an embodiment of the present invention. 1--Exchange network 2-Digital subscriber circuit DLC 3-Analog subscriber circuit 5LC 4-Digital subscriber line 5-Line termination device NT 7-Analog telephone 25--Polar line inversion circuit 26--Subscriber line switching circuit trn 54-Subscriber line switching circuit EMG 61-Digital telephone

Claims (1)

[Claims] A subscriber is accommodated in the digital subscriber line, the subscriber circuit on the exchange side is equipped with a power supply circuit and a loop monitoring circuit, and the line termination device is equipped with a power receiving circuit for the power supplied from the power supply circuit. In a system where calls are made using subscriber lines, an analog telephone is connected via a subscriber line switching circuit installed in the line termination equipment, and a subscriber line switching circuit is connected to the subscriber line switching circuit installed in the subscriber circuit on the exchange side. An emergency call is made using a digital subscriber line, characterized in that the subscriber line switching circuit is equipped with an analog subscriber circuit, and when the subscriber line switching circuit is operated, it is possible to make a call using the analog telephone. method.