JP2828664B2 - Digital public telephone - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital public telephone connected to a digital interface for transmitting and receiving a telephone call and a subscriber line signal between a terminal and a station device as a digital signal.

[Conventional technology]

A conventional public telephone uses an analog interface, but does not have an external interface for connecting a portable data terminal or the like or an auto dial device. For this reason, these data terminals and auto-dial devices have achieved their respective objects by transmitting a voice band signal to a handset of a public telephone.

In a portable data terminal, a voice coupler is mechanically fitted to a handset, and data is transmitted and received by modulating the data into a voice band. Auto dial devices use the fact that most analog public telephones use PB signals for line selection signals, and
The signal is converted to a PB signal and output to the transmitter to achieve the purpose.

Although not a public telephone, there is generally a terminal adapter for converting an existing terminal for an analog interface into a digital interface for connection as a related device. This will be described with reference to FIG.

In FIG. 2, reference numeral 200 denotes an existing analog terminal used by connecting to an existing analog network, and 300 denotes a digital exchange. Reference numeral 400 denotes a terminal-side terminal (digital service unit) of the digital-compatible exchange 300, and reference numeral 500 denotes a terminal adapter.

Since each part of 1 to 8, 14 to 16 constituting the terminal adapter 500 will be described in an embodiment of the present invention described later,
Here, the overall operation outline will be described.

When the analog terminal 200 is connected via the terminal adapter 500 and an input signal such as a PB signal is sent from this terminal, the signal is converted into a digital signal internally, and the digital switch
Sent to 300. A transmission signal from the digital exchange 300 is converted into an analog signal by the terminal adapter 500 and transmitted to the analog terminal 200.

In this case, since the terminal adapter 500 does not have a billing function, the terminal adapter 500 is modified so that a billing signal for an analog public telephone can be output to the analog interface side, and the digital interface side can also receive the billing signal of the digital public telephone. It is conceivable to modify the software in such a way to connect an analog public telephone to the digital interface via the modified terminal adapter.However, the analog line selection signal is received and analyzed, converted to a digital interface dial signal and transmitted. There is no public telephone having a digital interface to which a terminal having an existing analog interface with a function can be connected.

[Problems to be solved by the invention]

A public telephone for the analog interface may have an existing terminal connection interface. However, only a method of calling from the public telephone and switching to the connected terminal when connected to the other party is considered. This is because both the call control signal and the billing signal are not coded in the analog interface as in the digital interface, so if a call is made from a connected existing terminal, it is necessary for the public telephone to have a function equivalent to that of the exchange. This is because there is a disadvantage that the scale of hardware and software such as mechanical switches such as relays and their control is increased. If the terminal adapter is modified,
Although only the functions of the analog public telephone can be used, there is a disadvantage that the circuit scale for generating the reversal signal, which is a billing signal for the analog public telephone, becomes large. Also,
In the digital interface, the line selection signal (dial) itself is also coded. In the case of an analog dial, the PB signal that can be used in the line selection signal is transmitted from the transmitter as it is to the auto dial, which uses the line selection signal itself Cannot be used as it is because they are different.

[Means for solving the problem]

A digital public telephone according to the present invention comprises: a selection signal reception analysis section for receiving and analyzing a line selection signal of an analog interface; a level conversion section for converting a subscriber line signal for an analog interface to a predetermined level for transmission and reception; Input switching means for switching the input to the signal reception analysis unit to the level conversion unit or the transmitter, and for switching the digital signal to an analog signal, and the input / output to the codec for performing the reverse conversion to the level conversion unit or the handset. It has input / output switching means, output switching means for switching the output of the tone generation section to a level conversion section or a transmitter, and input switching means, input / output switching means, and a switch for instructing switching of the output switching means.

[Action]

In the present invention, an existing analog interface terminal that uses a PB signal as a line selection signal is changed to an input source to a selection signal reception analysis unit and a codec and an output destination of a tone generation unit according to a user operation procedure. Calling from the existing analog interface terminal to be switched, and PB via the digital public telephone handset
You can dial with a signal.

〔Example〕

FIG. 1 shows an embodiment of a digital public telephone according to the present invention. In this figure, 100 is a digital public telephone, 2
00 is an analog terminal used by connecting to an existing analog network,
300 is a digital exchange. Reference numeral 400 denotes a terminal terminating device (digital service unit) of the digital exchange 300.

Next, details of the digital public telephone 100 will be described. Reference numeral 1 denotes a microprocessor for controlling the digital public telephone 100. 2 is a digital public telephone 100
Is a work storage memory required for the microprocessor 1 to operate. 4 assembles or decomposes the frame of the digital signal, extracts the signal channel (B channel) and the control channel (D channel), and passes the D channel signal to the microprocessor 1 in parallel, Is a digital signal control unit that puts the parallel signal on the D channel. Reference numeral 5 denotes a driver / receiver for matching the signal levels of the digital service unit 400 and the digital signal controller 4. A codec 6 converts a digital signal into an analog signal or vice versa. A selection signal receiving / analyzing unit 7 receives and analyzes the input analog line selection signal, converts it into a code, converts it into a parallel signal, and outputs it to the microprocessor 1. 8 is a digital public telephone
A tone generator that generates various sounds (dial tone, busy tone, PB tone, etc.) used in the 100. 9
Is a switching unit using a switching switch such as a mechanical switch or a semiconductor switch, and is composed of an input switching unit 9a, an input / output switching unit 9b, and an output switching unit 9c. Reference numeral 10 denotes a handset of the digital public telephone 100, which comprises a handset and a handset. 11 is a hook switch, 12 is a display, and 13 is a dial. Reference numeral 14 denotes an analog terminal connection port for connecting an existing analog terminal. Reference numeral 15 denotes a level converter for converting the electrical level of the analog line interface into a level that can be input to the codec 6. 16 is the state of the lines L1 and L2 of the analog terminal 200 (loop closed,
This is an analog subscriber signal detection unit that monitors a call control state (eg, loop release) and detects the state. Reference numeral 17 denotes a changeover switch, which is connected to the microprocessor 1.
Reference numeral 18 denotes a billing processing unit that performs billing processing (acquires a telephone card or a coin and stores a call charge, etc.) as a public telephone according to a command from the microprocessor 1. Reference numeral 19 denotes a power supply for supplying power necessary for operating various parts of the public telephone and an analog interface, and reference numeral 20 denotes a connection detection sensor that detects whether the analog terminal 200 is connected to the analog terminal connection port 14. Is what you do.

Hereinafter, the operation of digital public telephone 100 according to the present invention will be described in detail.

When the power supply 19 is turned on, the hook switch 11 is turned on (the handset 10 is disconnected) or the analog terminal 200 is connected to the analog terminal connection port 14 and the changeover switch 17 is turned on. wait. Hook switch 11
Is turned on first, the switching unit 9 is switched to the handset 10 side (solid line in the figure), and waits until the billing processing unit 18 notifies that a telephone card or a coin has been inserted.

Therefore, when the handset 10 is removed first, the codec 6, the selection signal reception analysis unit 7, and the tone generation unit 8 are connected to the handset as shown by the solid line in the drawing. When a notification that a telephone card or a coin has been inserted is sent from the billing processing unit 18, it is checked whether the information is a value sufficient to permit calling, and if OK, the dial is inserted. A prompt message is displayed on the display 12. Normally, when the user presses the dial 13 attached to the digital public telephone 100, the microprocessor 1 receiving the dial 13 includes it as a line selection signal of the digital line interface in the call setting signal, and then sets the digital signal control unit. Send to 4. Here, instead of pressing the dial 13, a PB sound output unit of an auto dial device (not shown) capable of outputting a PB signal as a dial signal is pressed against the mouthpiece of the handset 10 of the digital public telephone 100, When the PB signal for line selection is output from the auto dial device, the operation is as follows.

The output of the handset of the handset 10 has a selection signal reception analysis unit 7
Is connected. The PB signal from the auto-dial device pressed against the mouthpiece of the handset 10 is input to the selection signal reception analysis unit 7 through the handset. The selection signal reception analysis unit 7 analyzes which combination of the frequencies of the input PB signals is a specified code (0 to 9, #, *, A, B, C, D). The result of the analysis (signal code) is notified to the microprocessor 1. The microprocessor 1 includes this signal code in the call setting signal of the digital interface as a line selection signal in the same manner as the dial code from the dial 13, and sends it to the digital signal control unit 4. At this time, while the PB signal is being input from the transmitter, the input from the dial 13 of the digital public telephone 100 can be ignored or both can be simultaneously superimposed and transmitted as a line selection signal. It is.

On the other hand, the analog terminal 200
When the connection detection sensor 20 detects that the connection has been made, and the changeover switch 17 is turned on, the changeover unit 9 is switched to the level conversion unit 15 side (broken line in the figure), and the charging processing unit 18 is switched. Waits for a notification that a telephone card or a coin has been inserted. Therefore, when the analog terminal 200 is first connected to the analog terminal connection port 14 and the changeover switch 17 is pressed, the codec 6, the selection signal reception analysis unit 7, and the tone generation unit 8 are connected to the analog terminal connection level conversion unit. Connected to 15. When a notification that a telephone card or a coin has been inserted is sent from the billing processing unit 18, the information processing unit checks whether the information is a value sufficient to permit a call.
Calling from 200 is permitted, and the error is displayed on the display unit 12.

The user uses the function of his / her own analog terminal 200 connected to the analog terminal connection port 14 to close the loop. The digital public telephone 100 detects that the loop has been closed by the analog subscriber signal detector 16 and notifies the microprocessor 1 of the fact.

The microprocessor 1 controls the tone generator 8 to generate a dial tone. This dial tone is transmitted to the existing analog terminal 200 via the level converter 15, and the analog terminal 200 outputs a line selection signal as a PB signal.

This PB signal is input to the selection signal reception analysis unit 7 via the level conversion unit 15, and is input to the selection signal reception analysis unit 7.
A code (0 to 0) defining the combination of the frequencies of the PB signal
9, #, *, A, B, C, D), and notifies the microprocessor 1 of the analysis result (signal code). The microprocessor 1 dials this signal code
It is included in the call setting signal of the digital interface as a line selection signal in the same manner as the dial code from 13 and sent to the digital signal control unit 4.

Similarly, a call control signal other than the call connection of the existing analog terminal 200 is also detected by the analog subscriber signal detection unit 16,
The call control signal is replaced with a call control signal of the digital interface and sent to the digital signal control unit 4 to disconnect the digital network. Conversely, the digital interface call control signal from the network is converted into an analog signal by the digital public telephone 100 and transmitted to the analog terminal.

For example, when the connection is disconnected from the network, the microprocessor 1 instructs the digital signal control unit 4 to disconnect the signal channel and to generate a busy tone to the tone generation unit 8. The analog terminal 200 knows that it has been disconnected from the network by this busy tone, and releases the loop.

As a procedure at the time of call connection, in addition to the above, the existing analog terminal 200 is connected to the analog terminal connection port 14, and the handset 1
There is also a method in which a call is made using the dial 13 of the digital public telephone 100 by raising 0, confirming that the other party has been connected, and pressing the changeover switch 17 to switch the codec 6 to the level conversion unit 15. When the changeover switch 17 is pressed at the time of answering the partner, the switching unit 9 may be switched to the level conversion unit 15.

〔The invention's effect〕

As described in detail above, the present invention provides a selection signal reception analysis unit that receives and analyzes a line selection signal of an analog interface, a level conversion unit that converts a subscriber line signal for an analog interface to a predetermined level and transmits / receives the signal. Input switching means for switching the input to the selected signal receiving / analyzing section to a level converting section or a transmitter, and a level converting section or a transmitting / receiving section for inputting / outputting a digital signal to an analog signal and input / output to a codec for performing the reverse conversion. Input and output switching means for switching the output of the tone generation unit to a level conversion unit or a transmitter, and an input switching means, an input / output switching means, and a switch for instructing switching of the output switching means. Select signal reception solution based on the difference in line selection signal system between public telephones and analog public telephones By absorbing in parts, it is possible to auto dial using an auto dial device having a PB signal transmission function from the transmitter that was available in the analog public telephone. Further, the tone generation unit and the selection signal reception analysis unit originally possessed by the digital public telephone are switched by the switching unit, and a call can be made from the existing analog terminal via the level conversion unit. Existing analog terminals include, for example, a portable facsimile and a personal computer with a portable modem, which can be connected to a digital public telephone and used to make a call and perform communication using an auto dial function or the like. The benefits are great. Since only the portion related to charging is performed by the digital public telephone, there is an advantage that the existing analog terminal can be used without modification. In addition, under the current situation where the number of lines is much greater than the existing analog interface than the digital interface, in most cases, even if a call is made from the digital interface, the other party is the analog interface. Even if it does, since the modem for the analog interface is widespread, there is an excellent effect that the existing terminal resources can be used as it is.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention,
FIG. 2 is a block diagram showing an example of a conventional terminal plaza. In the figure, 1 is a microprocessor, 2 is a program storage memory, 3 is a work memory, 4 is a digital signal control unit,
5 is a driver / receiver, 6 is a codec, 7 is a selection signal reception analysis unit, 8 is a tone generation unit, 9 is a switching unit, 9a is an input switching unit, 9b is an input / output switching unit, 9c is an output switching unit, and 20 is an output switching unit. It is a connection detection sensor.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04M 17/00 H04M 1/00

Claims (1)

(57) [Claims] In a digital public telephone having a digital interface for transmitting / receiving a telephone line signal and a subscriber line signal as a digital signal, a selection signal reception / analysis section for receiving and analyzing a line selection signal of an analog interface, for an analog interface A level conversion unit for converting the subscriber line signal to a predetermined level for transmission and reception, input switching means for switching the input to the selection signal reception analysis unit with the level conversion unit or the transmitter, a digital signal to an analog signal, Further, input / output switching means for switching input / output to a codec for performing the reverse conversion with the level conversion unit or handset, output switching means for switching output of a tone generation unit with the level conversion unit or handset, and the input Switching means, input / output switching means, output switching means Digital public telephone, characterized in that it comprises a changeover switch to.