JPS61222353A - Private line talking system - Google Patents

Abstract

PURPOSE:To return a ring-back tone possible for listening by using an intermittent DTMF (Dual Tone Multi Frequency) signal as a call signal to output the call signal with a large output. CONSTITUTION:When a handset of a caller side telephone set 8 is lifted, notice of hook-off is given to a telephone set control circuit 15. The circuit 15 actuates a DTM oscillator 16 and switches an analog gate 17 in a period of on (1sec) and off (2sec). Thus, the DTMF signal is outputted to a line 1a with an output of -4.5dbm. The signal acts like a call signal. When the DTMF signal is inputted to the reception side, a DTMF signal detection circuit 19 detects the signal and gives notice to a telephone control circuit 15 to switch an analog gate. An oscillator 18 makes oscillation to send a signal to the line with an output of -4.5dbm. Thus, a ring-back tone is returned.

Description

Detailed Description of the Invention (a) Technical field This invention relates to a telephone system for making telephone calls via a dedicated line, and in particular relates to an improvement in a calling method (b) Summary of the invention The dedicated line telephone system according to the present invention is A DTMF signal is used as a calling signal on the calling side, and the called side emits a ring bank tone until it is hooked off.

(C) Prior Art and Its Disadvantages In addition to in-store CDs and ATMs, financial institutions including banks have installed so-called outside CDs in hospitals, airports, department stores, etc. for the convenience of users.

These CDs, like the in-store CDs mentioned above, are online via a dedicated line. In the event that a user encounters a problem during operation of such a CD, the current method is to use a regular telephone connected to a public telephone line to contact maintenance personnel. However, with this system, the user must perform laborious tasks such as dialing the contact telephone number himself, and improvements have been desired from the viewpoints of maintenance efficiency and user service.

Therefore, in Japanese Patent Application No. 59-217084 and No. 59-217085, the applicant proposed that it is possible to make calls with maintenance staff etc. via dedicated lines that are online for ATMs, CDs, etc. We have proposed a telephone call system that can However, the standards for dedicated lines are set by the Telegraph and Telephone Public Corporation, and according to these standards, as shown in Figure 6, the audio signal is -4,5
dbm, but digital data is only authorized to be output at -10 dbm, and 400 Hz continuous signals used for calling signals on dedicated lines are only allowed to be output at -25 dbm. Therefore, not only can the ringing signal be caught up in interference and become unrecognizable, but even if a response signal to the call is returned from the other party, there is a response tone (ringback) that can be heard on the telephone that received the response signal. There was the inconvenience of having to synthesize the tones). As a result, the equipment became complicated, which also caused an increase in cost.

(d) Purpose of the Invention In view of the above-mentioned drawbacks, the object of the present invention is to provide a dedicated line communication system that is capable of transmitting a high-output calling signal and returning an audible output ring-back tone when the calling signal is received. do.

(e) Structure and Effects of the Invention The present invention provides a dedicated line communication system comprising a dedicated line to which a data terminal is connected and two communication terminals that perform voice communication via this line. A DTM message is sent to each call terminal device, and the caller detects that the receiver picks up the handset (hook-off) and connects the receiver to the other party's device.
F (Dual Tone Multi Freque
(ncy) means for transmitting a signal, means for oscillating a ringing bell sound when the DTMF signal is received on the called side, and means for returning an intermittent signal of a specific frequency to the calling side, and means for generating a ringing ring sound on the called side. means for connecting the handset to the line by stopping the oscillation of the ring tone and returning the intermittent signal of the specific frequency, and when the input of the intermittent signal of the specific frequency stops on the calling side; The present invention is characterized by comprising means for stopping transmission of the DTMF signal and connecting the receiver to the line.

As described above, according to the present invention, by using intermittent DTMF ('g) in the paging signal, paging can be performed with an output of -4.5 dbm, and the called party receiving this paging signal The call terminal device transmits a specific frequency (400
A ringback tone, which is an intermittent signal (such as Hz), is directly returned. Therefore, there is no need to use a high-performance device to identify the calling signal, and the calling terminal device does not need to synthesize the ringback tone after receiving the response signal, which simplifies the device configuration. , the response signal of the other party's telephone can be heard directly on the handset, giving the user a sense of security.

(f) Embodiment FIG. 2 is a schematic block diagram of a dedicated line communication system which is an embodiment of the present invention. The dedicated port wAl is a full-duplex line (1a, 1b) that can perform transmission and reception simultaneously. A control unit A is connected to each end of this dedicated line 1,
This control unit A includes a telephone 8° data terminal device (rD
TEJ) 4 is connected. These control parts A
, telephone 8 and DTE 4 constitute a superimposed communication device.

FIG. 3 is a block diagram of the superimposition communication device. In the figure, a dedicated line 1 is connected to a transformer 2, and a dedicated line on the transmitting side is further connected to an adder 3. A modem 5 is connected to the DTE 4 and transmits data.

The received data is sent via a bandpass filter 6 and an adder 3 to a dedicated line 1 on the transmitting side. The received data passes through a low-pass filter 7, is output to the modem 5, and is guided to the DTE 4. Further, a dedicated port vA1 is connected to a telephone terminal device including a telephone 8 and a telephone connection section 9 attached to the DTE 4 through a low-pass filter 10.11, respectively. The low-pass filter 10.11 is for separating audio signals, and the band-pass filter 6.7 is for separating data.

FIG. 1 is a block diagram of the telephone terminal device. The transmission line 1a of the dedicated line 1 is connected to the adder 21, and the reception line 1b is connected to the terminal 12 of one primary winding of the transformer 12.
connected to a. The adder 21 is also connected to the other terminal 4a of the primary winding of the transformer 12, and is connected to the DTMF oscillator 16 via an analog gate (17.20).
．． 400 Hz oscillator 18. Further, a DTMF detection circuit 19 is connected to the reception line 1b. The opening and closing of analog gates 17 and 20 are both controlled by telephone control circuit 15. The primary @ line of the transformer 12 is provided with an intermediate tap and is grounded. One terminal 8a of the telephone 8 is connected to one terminal 12c of the secondary winding of the transformer 12 via a DC component cutting capacitor 22, and the other terminal 8a of the telephone 8 is connected to the other terminal 12d of the secondary winding. Terminal 8b is directly connected. A resistor 23 and a cathode of a light emitting diode 13a built in the photocoupler 13 are connected to the terminal 8a of the telephone. These resistors 23. The other terminal of the diode 13a is connected to a common terminal of a relay switch 24a. The other terminal 8b of the telephone 8 is directly connected to the other relay switch 2.
It is connected to the common terminal of 4b. The relay switches 24a and 24b are turned on and off at 16 Hz when the telephone control circuit 15 rings the bell of the telephone 8.

A battery 25 is connected to these relay switches 24a and 24b via an impedance element 26, and when the hook is on, ten poles are connected to the switch 24a and one pole is connected to the switch 24b. When the relay 24 is turned on under the control of the telephone control circuit 15, one pole is connected to the switch 24a and ten poles are connected to the switch 24b, and at this time the bell of the telephone 8 rings.

An off-hook detection circuit 14 is connected to the photocoupler 13, and this off-hook detection circuit 14 is connected to a telephone control circuit 15. When the handset of the telephone 8 is picked up (hook-off), a current flows through the resistor 23 and a voltage drop occurs, so a current flows through the light emitting diode 13a and emits light, and the output of the photocoupler 13 is input to the off-hook detection circuit 14. Ru. Off-hook detection circuit 14
detects the hook-off and notifies the telephone control circuit 15 of the hook-off.

Telephone control circuit 15 includes DTMF detection circuit 19. as described above. Analog gate 17.20, DTMF oscillator 16.400Hz based on the output of photocoupler 13
Controls transmitter 18 and relay 24.

FIG. 4 is a diagram showing a signal sequence when two terminal devices are connected through a dedicated line.

When the handset of the calling party's telephone 8 is picked up, the photocoupler 13. The off-hook detection circuit 14 notifies the telephone control circuit 15 that the hook is off (a).

The telephone control circuit 15 operates the DTMF oscillator 16 and turns on the analog port gate 17 for one second.
Opens and closes with a 2 second off cycle. This allows DTMF
The signal is sent to line 1a with an output of -4.5 dbm (
b). This signal functions as a calling signal for the other party's terminal device.

In the terminal device on the receiving side that receives the intermittent DTMF signal through the dedicated line, the DTMF signal is transferred to the receiving line 1.
When the signal is input through b, the DTMF signal detection circuit 19 detects the signal and notifies it to the telephone control circuit 15 as a call signal input, and also turns on the analog gate 20 at a cycle of 1 second on and 2 seconds off. Open and close. At this time, the 400Hz oscillator 18 applies -4.5db to the line.
It oscillates with enough output to send out a signal at the output of m.

As a result, the ringback tone is sent back to the calling terminal device on the oscillator side (C). This ring bank tone is a repetition of 16×2 amplitude modulated signal periods of 1 second followed by 2 second pauses. Since this signal is an intermittent signal, it is treated as an audio signal according to the standards of the Telegraph and Telephone Public Corporation, and can be transmitted at an output of -4.5 dbm. At the same time as the above operation, the telephone control circuit 1
5 turns the relay 24 on and off to ring the bell of the telephone 8 (d). In the terminal device on the originating side, since the returned intermittent signal has sufficient output, it can be heard as a ringback tone on the receiver of the telephone set 8.

On the receiving side, when the attendant picks up the telephone receiver (hook-off) in response to the ringing bell, the relay switch 24a is activated.
, resistance 23. Telephone 8. Current flows through the relay switch 24b and a voltage drop occurs across the resistor 23, so current flows through the light emitting diode 13a and emits light. This light emission causes the photo coupler 13. Off-footer detection circuit 14 notifies telephone control circuit 15 of the hook-off. The telephone control circuit 15 stops the ringing of the telephone 8 since it is now possible to make a call, and transmits the 400 Hz transmitter 1.
8 to stop transmitting the intermittent signal (e), and
Open analog gate 20.

When the 40011z intermittent signal from the receiving terminal is stopped, the 400 detection circuit 2 of the calling terminal notifies the telephone control circuit 15 of this.

Accordingly, the telephone control circuit 15 determines that the receiver of the telephone 6 on the receiving side has been picked up. The telephone control circuit 15 causes the DTMF oscillator 16 to stop transmitting the continuous signal (f) and opens the analog gate 17. As a result, a line is established between the telephones of both terminal devices, and a telephone conversation is possible. FIG. 5 is a diagram showing a timing chart of the above signals.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a telephone terminal device used in a dedicated line telephone communication system which is an embodiment of the present invention, FIG. 2 is a schematic block diagram of the above embodiment, and FIG. 3 is a terminal device of the above embodiment. A schematic block diagram of the superimposition communication device, FIG. 4, is shown above through a dedicated line. FIG. 5 is a diagram showing a signal sequence when two terminal devices are connected, FIG. 5 is a diagram showing a timing chart of the above-mentioned signals, and FIG. 6 is a diagram showing the dedicated line output standard of the Telephone and Telecommunications Public Corporation. 16-DTMF oscillator, 18400Hz oscillator, 19-
DTMF detection circuit.

Claims (1)

[Claims] (1) A dedicated line to which the data terminal is connected, and two call terminals that perform voice calls via this line;
In a dedicated line communication system consisting of
means for transmitting an intermittent signal of a specific frequency on the called side, means for oscillating a ringing bell sound when the DTMF signal is received on the called side, and means for returning an intermittent signal of a specific frequency to the calling side; means for connecting the handset to the line by stopping the oscillation of the ring tone and returning the intermittent signal of the specific frequency, and when the input of the intermittent signal of the specific frequency stops on the calling side; A dedicated line communication system comprising: means for stopping transmission of the DTMF signal and connecting the receiver to the line.