JPS6112161A - Talking control system in public telephone set - Google Patents

Abstract

PURPOSE:To attain ease of discrimination of mis-operation and incorrect operation by disabling transmission if a dial number is an inhibited number, cutting off a DC loop circuit when incorrect number to disable reception and transmitting an audible tone to a receiver. CONSTITUTION:A control section CNT judges the presence of a deposited coin in response to the detection output of a coin detection circuit CCD and when it is judged to be an inhibited number, restoration control is applied to a block relay TS only, a contact ts<1> by-passes a transmitter T to disable the transmission. Further, when it is judged as an incorrect number, a switch SW is controlled to open a DC loop circuit forcibly for a prescribed time, the restoration control to the by-pass relay SS is attained, the transmission/reception by a contact (ss) is disabled, an oscillator OSC is controlled, an audible tone signal corresponding to a busy tone is generated and transmfitted to a receiver R of a talking circuit TKC. Thus, when the inhibited number is dialed, the transmission is disabled, and when an incorrect number is transmitted or a coin is stored incorrectly, an audible tone is listened to.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a system for controlling calls in a public telephone according to a dialed number to be called.

[Prior art]

Public telephones use various call control methods depending on the type of phone, but they monitor the dialed numbers that are generally dialed and allow calls to be made free of charge if they are a specific number for emergency calls, while they allow calls to be made free of charge if they are a specific number for emergency calls. However, if the number is prohibited to a toll number, calls will be blocked.

For this reason, especially in public telephones that are controlled by the exchange power supply via the telephone line, if a prohibited number or an unauthorized number that results in a fraudulent call is made, completely opening the DC loop circuit will cause the control based on the loop current to Because the local power supply disappears and subsequent control becomes impossible, we can disable only transmitting calls, or open the DC loop circuit for a certain period of time, thereby temporarily restoring the exchange and then reacquiring it. At the same time, means have been adopted to disable sending and receiving calls.

However, in the former method, the inability to make a call is canceled by reversing the polarity of the line voltage in response to a response from the other party, and there is no polarity reversal during an emergency call, making it impossible to make an emergency call. The drawbacks of this method include the fact that it is not desirable for the user, as it is not possible to make a call due to the use of a prohibited number, or whether a similar situation has occurred due to the use of an unauthorized number. is occurring.

[Summary of the invention] ゛The present invention has the purpose of fundamentally solving the drawbacks of the conventional technology.If the dial number to be dialed is a prohibited number, it will be impossible to send a call, and if it is an illegal number, the DC loop will be terminated. This invention provides an extremely effective call control method for public telephones that forcibly disconnects the circuit, disables at least receiving calls, and sends an audible tone generated by a built-in oscillator to the receiver. be.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to circuit diagrams showing embodiments.

In the figure, a hook switch H8 and a switch SW made of a switching element such as a transistor are inserted into the loop circuit between the line terminal Ll to which the telephone line is connected and one end of the communication circuit TKO. A constant voltage diode ZD1 is connected between the other end of the circuit TKC and the other end of the circuit TKC.
has been inserted.

For this reason, a DC loop circuit is closed in response to off-hook, and a loop current is passed through these, and the zener voltage of the constant voltage diode ZDI inserted in the direction that generates a zener voltage with respect to the loop current that is the positive electrode of the line terminal Lx'ik. As a result, the capacitor CI is charged via the reverse current blocking diode D1, and the control unit CNT performs control operations in response to this terminal voltage being supplied as a local power source.

However, a contact s8 of a magnetic latching type bypass relay SS is connected in parallel to the communication circuit TKC, and a similar blocking relay TS is connected to the transmitter T of the communication circuit TKO. The contacts t and i'' are connected in parallel, making it impossible to send or receive calls. Therefore, it is impossible to make a call only by going off-hook.
NT operates each relay 88 . in response to the detection power of a coin detection circuit COD including a photoelectric detector etc. arranged in a coin storage mechanism (not shown). By driving the operating winding F of the TS, each relay 88. SR maintains operation, contacts ms', ts
” is turned off, making it possible to make and receive calls.
In response to the control of the dial circuit D゛IC in response to the operation of the board KB, the switching element in the call circuit TKC is turned on.
In accordance with turning off, dialing is performed.

Note that each relay 88. Restoration winding R# of TS, capacitor C in response to hook switch H8 being turned on due to on-hook.
1 is activated while not discharging, thereby causing each relay 88 . The TS will be restored.

On the other hand, the control unit CNT is directly given the output of the keyboard Kn, and when a dial call is made, the control unit CNT monitors the dialed number and prohibits calls to a toll relay stand, etc. The system determines whether the number is a prohibited number, or whether it is an unauthorized number that is similar to a specific number that allows free calls, such as a four-digit number, that would result in an unauthorized call, and then controls are carried out according to the results.

That is, the control unit CNT also determines the presence or absence of an inserted coin according to the detection power of the coin detection circuit COD, and
If it is determined that the number is a prohibited number, recovery control is performed only on the blocking relay TS, and the transmitter T is bypassed by its contact ts1, making transmission impossible.

If it is determined that the number is an unauthorized number, it controls switch 8Wf, turns it off for, for example, 1 second, forcibly opens the DC loop circuit for a certain period of time, performs recovery control on bypass relay SS, and uses contact 8B' to Built-in oscillator that disables sending and receiving calls and operates using local power supply
sc'1 is set in an oscillating state to generate an audible sound signal equivalent to, for example, a busy tone, and this output is sent to a matching transformer MT.
The signal is then sent to the handset R of the communication circuit TKO via the capacitor C2.

If the control unit CNT determines based on the detection power of the coin detection circuit CCD that the coin is not stored properly or that there are no coins to be stored during a call, the same control as described above is performed. It will be done.

Therefore, if you make a mistake in calling a prohibited number to a toll relay stand, etc., you will be able to listen to the other party's calls, but you will not be able to send your own calls. If a storage problem occurs, the built-in oscillator O8C must be activated.
This allows the user to immediately determine the cause of the call failure, and also allows emergency calls to be made free of charge to specific numbers.

Then, each relay 88. The TS may be one that uses a permanent magnet to hold multiple actions, or one that holds the action mechanically. Depending on the situation, break contacts or transfer contacts may be used for the contacts sa and ts. Ash,
The operation and recovery of each relay SS and TS may be in an opposite relationship, and the contact point as.

ts" may be connected to at least a part that makes it impossible to receive calls from the telephone line, and a part that makes it impossible to send calls and does not interfere with the closing of the DC loop circuit.

In addition, the control unit CNT'i may be constructed by combining various logic circuits without using a processor in particular, and the dial circuit DIC may be configured not only to send out pulse signals but also to send audio frequency signals. It is also possible to use one that sends out as a dial signal.

Note that if the output of the keyboard KB is given to the control unit CNT and the dial circuit DIC, the number of output ports of the control unit CNT can be reduced.
The present invention can be modified in various ways.The present invention can be modified in various ways.The present invention can be modified in various ways.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, control is carried out according to the dialed number to be called, calls based on erroneous or fraudulent operations are completely prevented, and emergency calls are allowed. This has the remarkable effect of making it easier to distinguish between erroneous operations and fraudulent operations.

[Brief explanation of drawings]

The figure is a circuit diagram showing an embodiment of the present invention. Ll, L2...Line terminal, H811H8"...
Hook switch, SW... switch, TKO...
・Telephone circuit, T...Telephone, R...Q receiver, Z
D,・Φ・・Voltage diode, DI・・e・Diode, c1+c2・・Capacitor, CNT@-・
・Control unit, D engineering C...Dial circuit, KB-...
Keyboard, MT/111111 matching transformer, O8C/
...Oscillator, SS...Side relay, TS...
15 [1 stop') し、as、ts・・・Contact. Patent applicant Tamura Electric Manufacturing Co., Ltd. Nippon Telegraph, Public Telephone Corporation

Claims (1)

[Claims] In a public telephone that monitors a dialed number to make a call and performs predetermined call control according to the dialed number, if the dialed number is a prohibited number that should be prohibited, the call is disabled and the dialed number becomes an unauthorized call. A call control system for a public telephone set, characterized in that, when the number is an invalid number, the DC loop circuit is forcibly disconnected, at least the call cannot be received, and an audible tone generated by a built-in oscillator is sent to the receiver.