JP3033756B1 - Prepaid phone with residual alarm - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To intuitively know the number of remaining calls that can be made according to the usage tendency of a user, and to add a frequency at a timing according to the usage tendency of a telephone and to save telephone usage. It is an object of the present invention to provide a prepaid telephone with a frequency warning device. SOLUTION: When a customer database storing available frequencies based on a prepaid contract is connected to a network 10, and when a line interface unit 11 receives residual frequency information transmitted from the network 10 via a telephone line 10a at the end of a call. On the basis of the remaining frequency information, the control unit 13 obtains a guideline of how many remaining calls can be made from the frequency of calls stored in the memory unit 12, and when the remaining frequency falls below a predetermined value, the control unit 13 displays it on the display unit. At the same time as visually indicating that the remaining number of calls is low, a warning sound is generated from the warning sound sending unit, which also notifies the user audibly, and warns the remaining number according to the usage tendency that differs for each user. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for controlling a current remaining amount according to a user's usage tendency by using a memory or the like based on residual frequency information received at the end of a call by a line interface unit. Calculate the approximate number of calls that can be made by the number of times, display and warn, and intuitively show the user how many calls can be made later, the user can The present invention relates to a prepaid telephone with a residual number warning device, which facilitates addition of a frequency and saving of telephone use at a timing according to a tendency of telephone use.

[0002]

2. Description of the Related Art Most current telephone services have a post-pay system in which call charges are totaled and collected monthly. On the other hand, in a prepaid telephone service that collects a fee in advance, a frequency corresponding to the prepaid fee is used as a measure of how much the service can be used later. The prepaid phone service has a maximum call charge when it is used for the purpose of operating under a specific management, such as when the charge is exceeded by a long phone or when the parent gives the child a mobile phone. There is an advantage that can be limited.

[0003] However, telephone charges vary according to the distance to the destination and the duration of the telephone call, and recently, telephone contracts with telephone carriers have been diversified. Because it is quite different, the frequency of reduction in frequency also varies greatly from user to user in that respect, and even in the same distance and the same time of call, there are many cases where the call fee changes considerably, and how much use is possible with frequency It was sometimes difficult to intuitively judge whether there was. For example, the partner is PHS
In such a case, the call charge becomes extremely high. As described above, depending on the situation of the call, the frequency can be reduced in various ways.

[0004]

As described above, in the prepaid telephone service, there is a problem that the number of remaining calls is consumed due to excessive calls and the telephone cannot be used at all times. is there. In order to prevent such a problem, it is necessary to clearly show the state of the residual frequency to the user during daily use. Also,
It is necessary to alert the user when the remaining number is low and to notify the user that the remaining number is running out and to alert the user that the telephone cannot be used. Become.

Therefore, for example, Japanese Patent Application Laid-Open No. 09-2332 discloses
No. 33 (base station, mobile station and communication control device between base station and mobile station) states that a mobile telephone terminal with a call charge prepaid function is only available when an incoming call is received if the prepaid registration remaining amount is 0 yen. When the user wants to make an outgoing call, the user operates the keypad to perform pre-payment registration of the call charge with the telephone prepaid card inserted in the card reader device. At that time, it is disclosed that the prepaid remaining amount, the user usage amount, and the card remaining amount are all displayed on the LCD.

However, in the case of this gazette, when the prepaid amount becomes 0 yen, the user operates the keypad with the telephone prepaid card inserted in the card reader device and prepaid the call charge. You need to register. Therefore, the user cannot know in advance before the residual number becomes zero, and as a result, as described above, the user cannot know the use state of the residual number during daily use, which is important. It is not a solution to the problem that the use of telephone is impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is possible to display the state of the residual number in a manner that is easy for the user to understand in daily use. Remaining number warning device that allows the user to know the estimated number of possible telephone calls according to the user's usage tendency, and to easily add a frequency at a timing according to the user's usage tendency and save telephone use. The purpose of the present invention is to provide a prepaid telephone system with a charge.

[0008]

In order to achieve the above object, a prepaid telephone system with a residual number warning device according to the present invention is connected to a telephone line connected to a line network, and has a prepaid charge based on a prepaid contract. A line interface unit for notifying the available frequency based on the line network from the line network, a memory for storing the call frequency, and a memory for storing the remaining frequency information received at the end of the call by the line interface unit, in the memory unit. When the remaining frequency of the call frequency is less than or equal to a predetermined value, the control unit displays a warning indicating that the remaining frequency is low as a warning message of the control unit, and the display unit displays the warning message at the same time as the warning message of the control unit. It is characterized by comprising a warning sound sending section for generating a warning sound indicating that the remaining number of remaining counts is small by control, and an operation section for performing an operation necessary for a call. To.

According to the present invention, in a telephone service based on a prepaid contract, information on the remaining number of times transmitted from the line network at the end of the call is received by the line interface unit, and the remaining number information received by the line interface unit is received. When the remaining frequency of the call frequency stored in the memory unit becomes equal to or less than a predetermined value, the display unit is controlled by the control unit, and a display indicating that the remaining frequency is small is displayed as a warning message of the control unit. At the same time, the control unit controls the warning sound sending unit to generate a warning sound indicating that the remaining number of calls is low based on the number of remaining calls according to the tendency of the user to use the telephone. In addition to the visual display, an audible warning is issued by the warning sound sending unit, and the user is reliably notified that the remaining number is low.

Therefore, according to the present invention, the value which is a rough estimate of the number of remaining calls according to the tendency of the user to use the telephone is roughly based on the consumption frequency at the time of the telephone call by the user. In addition to being able to know more visually and intuitively, the remaining number of calls based on the number of remaining calls based on the user's telephone use It is easier to add more frequencies and save on telephone use.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a prepaid telephone system with a residual number warning device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment according to the present invention. In this FIG.
A telephone line 10a is connected to the line network 10, and a control unit 13 is connected to the telephone line 10a through a line interface unit 11. The control unit 13 controls a display unit 14 (by an LCD panel) that can perform a warning display, a warning sound transmission unit 15 that transmits a warning sound, and a memory unit 12 that stores frequency information.
Are respectively controlled. That is, in addition to these controls, the control unit 13 controls necessary functions of the telephone, that is, controls the entire telephone, though not shown in the figure. An operation unit 16 is also provided on the telephone for performing operations necessary for communication.

As shown in FIG. 2, the memory unit 12 has an area 201 for storing the current value of the residual frequency (an area for storing the value of the residual frequency) and an area for storing the numerical value of the residual frequency of the previous call. 202 (the value of the remaining frequency is entered), the latest consumption frequency 203
(The value of the remaining frequency is entered), the consumption frequency 204 in the call “1”
(Consumption frequency value is entered), consumption frequency 20 in call "2"
Calls indicated by 5 (consumption frequency value entered) to consumption frequency 221 (consumption frequency value entered) for call "18" and consumption frequency 222 (consumption frequency value entered for call "19") There is an area for storing the numerical value of the consumption frequency for each "20" value, and an area for storing the numerical value of the standard number of times 223 (the number of times is entered).

The memory unit 12 stores the value of each area in the control unit 13.
It is assumed that the value does not change except at the time of rewriting the value, and that the value does not disappear even when the power is turned off. Memory unit 12
Is a unit that can write and read values at any time by the control unit 13.

The display section 14 is an LCD panel capable of lighting a dot and displaying a multi-digit number display and an arbitrary graphic display under the control of the control section 13, and is used in the first embodiment. The LCD panel has a display function shown in FIG. As shown in FIG. 3, the display contents of the LCD panel include, for example, "Warning", "Slightly remaining remaining number !!", "Remaining XXX times", and the like.

The warning sound sending section 15 is a buzzer that can turn on / off a warning sound by a signal from the control section 13.
The line interface unit 11 is connected to a telephone line 10a connected to the telephone company's line network 10 by a control signal line and a voice signal line (all of which are not shown). It has a function of transmitting and receiving control signals for controlling outgoing and incoming calls to and from the telephone 10, and transmitting and receiving voice signals via voice signal lines when a call is started.

The residual frequency information is sent from the line network 10 to the line interface unit 11 through the telephone line 10a as one of control signals. The operation unit 16 includes a plurality of button switches provided for the user to operate the telephone, and has a function of performing basic operations as the telephone. The control unit 13 is mainly configured by a CPU, and has a function of controlling the operation of the entire telephone according to the first embodiment.

In the prepaid telephone service network to which the telephone according to the first embodiment is connected, a user prepaid a charge to a business operator at a counter or the like, and the business operator makes a prepaid call. Charge (frequency) information is stored in a customer database (not shown) connected to the network 10. Each time the user makes an outgoing call, the frequency is
The subtraction processing is performed by the processing device on the side, and the residual count is stored in the database. The information on the remaining number is transmitted from the line network 10 to the user's telephone as one of the control signals through the telephone line 10a at the time of starting and ending the call by the user.

Alternatively, when the user performs an operation for confirming the residual number on the telephone during standby, the telephone transmits a control signal for referencing the residual number via the telephone line 10a using the interface unit 11. The information is transmitted to the network 10, and the line network 10 receiving the information transmits the information on the remaining number to the telephone of the user. In the first embodiment, the telephone stores the remaining number from among the remaining number information received from the line network 10 through the telephone line 10a, and stores the remaining number by operating the operation unit 16 by the user. It is capable of displaying the frequency value on the display unit 14. This allows the user to check how many residual counts there are.

Next, the operation of the first embodiment configured as described above will be described. In the description of the operation, the state in which the telephone according to the first embodiment is used by a specific user and the values shown in FIG. In this FIG.
For the sake of simplicity, the consumption frequency for each call is stored only for five times the consumption frequency from the last call to the four previous calls, but is actually shown in FIG. Save 20 calls.

Of the names stored in the memory 12 in FIG. 4, the current remaining frequency 401 is stored, and in this example, 495 (frequency) is entered. Current residual count 4
For 01, the remaining frequency 402 of the previous call is stored, and in this example, 500 (frequency) is stored. From the latest consumption frequency 403, the consumption frequency 407 for call "4"
Up to this time, the consumption frequency for each call is calculated and stored by the operation of the first embodiment.

The latest consumption frequency 403 stores the consumption frequency of the last call, that is, the latest consumption frequency. In this example, "6" (frequency) is entered. In the consumption frequency 404 for the call “1”, the remaining frequency in the previous call to the latest consumption frequency 403 is stored, and in this example, “3” (frequency) is entered. The consumption frequency 405 of the call “2” includes the latest consumption frequency 403.
, The remaining frequency of the previous two calls is stored, and in this example, “5” (frequency) is entered. In the consumption frequency 406 of the call “3”, the remaining frequency of the call three times before the latest consumption frequency 403 is stored, and in this example, “7” is used.
(Frequency) is included. Consumption frequency 4 with call frequency "4"
In 07, the remaining number of calls four times before the latest consumption frequency 403 is stored, and in this example, “4” (frequency) is entered.

In this example, for the sake of simplicity, the latest consumption frequency 403 to the consumption frequency 4 at the call frequency “4” are used.
As the consumption frequency for each of the five-valued calls up to 07, the oldest one is the consumption frequency for the four previous calls, but in practice, as shown in FIG. Since the consumption frequency for each of the 20 values of the consumption frequency 222 for the call "19" is stored, the oldest one in this case is the consumption frequency for the 19th previous call. The estimated number of times 408 in FIG. 4 includes a calculated number of remaining calls that can be made by the operation of the first embodiment. In this example, 99 (times) is entered.

The memory section 12 is in the state "1" of the memory section 12 in the embodiment shown in FIG. 4 (here, the state shown in FIG. 4 is referred to as "state" 1 "). Make a call from the user and make a call on the telephone that is in use. At the end of the call, the telephone network 10a
The remaining frequency information is transmitted through. In the first embodiment, it is assumed that 490 (frequency) is transmitted from the network 10 through the telephone line 10a as residual frequency information.

In the telephone according to the first embodiment,
When the line interface unit 11 receives the residual number information transmitted from the line network 10 through the telephone line 10a, the line interface unit 11 sends a signal to the control unit 13 to notify that the residual number information has been received. The control unit 13 that has received the signal first sets the value of the area where the current residual count is stored in the memory unit 12 indicated by the current residual count 401 in FIG.
It is copied to the area where the remaining number 402 of the previous call shown in FIG. 4 is stored. After that, the control unit 13 reads the value of the received residual frequency from the line interface unit 11 and writes the value into the area where the current residual frequency 401 shown in FIG. 4 is stored.

With this operation, the memory section 13 is brought into the state shown in FIG. In the memory unit 12 in the state “2” (here, the state in FIG. 5 is referred to as “state“ 2 ”) of the memory unit 12 in the first embodiment shown in FIG. On the other hand, the control unit 13 further sets the value of the area where the consumption frequency 506 for the call “3” shown in FIG.
Copy is made to the area where the consumption frequency 507 in the call 4 shown in FIG. 5 is stored. Next, the control unit 13 performs the call 2 shown in FIG.
The value of the area in which the consumption frequency 505 in is stored is copied to the area in which the consumption frequency 506 in the call 3 shown in FIG. 5 is stored.

Next, the control unit 13 sets the value of the area where the consumption frequency 504 for the call “1” shown in FIG. 5 is stored in the area where the consumption frequency 505 for the call 2 shown in FIG. 5 is stored. make a copy. Next, the control unit 13 copies the value of the area where the latest consumption frequency 503 shown in FIG. 5 is stored to the area where the consumption frequency 504 of the call 1 shown in FIG. 5 is stored. Finally, the control unit 13 subtracts the value of the current remaining number 501 shown in FIG. 5 from the remaining number 502 at the time of the previous call shown in FIG. 5 is copied to the area where the latest consumption frequency 503 is stored.

With the above operations, the memory section 12 changes from the state shown in FIG. 5 to the state shown in FIG. That is, FIG.
5, the value of the consumption frequency for each of the five values of the consumption frequency 503 in FIG. 5 to the consumption frequency 507 in the call "4" shifts, and the oldest consumption frequency is discarded. In the latest consumption frequency 603 shown in FIG. 6, the latest consumption frequency calculated corresponding to the latest remaining frequency received by the line interface unit 11 at the end of the call is stored.

The memory unit 12 becomes the state "3" of the memory unit 12 in the first embodiment shown in FIG. 6 (here, the state of FIG. 6 is referred to as "state" 3 "). After the above operation, the control unit 13 sets the latest consumption frequency 6 in FIG.
The consumption frequency of each of the five calls of the consumption frequency 607 from 03 to the call “4” is added to the sum of the five consumption values, so that the average value is obtained by dividing by five. In this example, (5 + 6 + 3 + 5 +
7) /5=5.2 (frequency). In the operation here,
Since the calculated standard number is rounded to the nearest whole number and used after rounding off the decimal point, the average value of the consumption frequency is 5 (frequency).

Next, the control unit 13 performs a calculation of dividing the value of the current residual frequency indicated by the current residual frequency 601 in FIG. 6 by the calculated average value of the consumed frequency. In this example, the average value of the consumption frequency is 5 (frequency), and the current value of the remaining frequency is 490, so the value obtained by dividing the value is 98 (times). The calculated value, 98 (times) in this example, is stored in the area of the memory unit 12 indicated by the reference number 608 in FIG.

After the end of the call, the memory unit 12
The state becomes the state 4 (here, the state of FIG. 7 is referred to as “state“ 4 ”) of the memory unit 12 in the first embodiment shown in FIG. Since the telephone according to the first embodiment performs the above operations every time after the end of a call, the memory unit 12 calculates and stores a new reference number every time a call is made.

In the above description of the operation, for simplicity of explanation, the consumption frequency for each call stored in the memory unit 12 is set to five values, but actually, as shown in FIG. 12 stores the value of consumption for each call of 20 values, and when calculating the average value of the consumption frequency, FIG.
Number of remaining calls from previous call 203 to call "19"
Is the average of 20 values of the consumption frequency 222. Further, in the example described so far, the value is set in each area of the memory unit 12 on the assumption that the telephone device has been used several times in advance. Since there is no remaining frequency of the previous call or the frequency of consumption in the past call, when the telephone according to the first embodiment is actually started to be used, no inconvenience occurs in FIG. Initial values as shown are set in the memory unit 12.

After the end of the call, the control unit 13 reads out the standard number of times stored in the memory unit 12 after performing the above-described series of writing processing to the memory unit 12 and when the power of the telephone device is turned on. Sends a signal to the display unit 14
The estimated number of calls is displayed in the part that displays the number of remaining calls.
Further, when the control unit 13 reads the reference number of times stored in the memory unit 12, the value is equal to or less than a certain value (this value is set to two times in the first embodiment,
It can be arbitrarily changed by the user. If the number of times has decreased to the number of times, a signal is sent to the display unit 14 and a warning indicating that the remaining number is low is displayed as a warning message. At the same time, a signal is sent to the warning sound sending unit 15 to confirm that the remaining number is low. Sounds the alarm sound shown.

As described above, in the first embodiment according to the present invention, the control unit 13 uses the memory 12 or the like to cause the user to use the memory 12 or the like based on the remaining frequency information received by the line interface unit 11 at the end of the call. In accordance with the usage trend of, the approximate number of calls that can be made with the current remaining number is calculated and displayed on the display unit 14, so that the user can talk later. It can be intuitively indicated.

Further, in the telephone according to the first embodiment, as a criterion for issuing a warning indicating that the remaining number is low, a guide number of how many telephone calls can be made according to the usage tendency of the user is used. Therefore, the user can receive a residual number warning according to the usage tendency of the user. As a result, the user can easily add a frequency at a timing according to his / her tendency to use the telephone and save the use of the telephone.

Next, another embodiment of the present invention will be described. As a second embodiment according to the present invention,
A wireless unit is added to the interface unit 11 of the telephone in the first embodiment, and the wireless
And the same operation as in the first embodiment can be performed.

Further, as a third embodiment of the present invention,
An issuance device such as an LED (Light Emitting Diode) is added to the telephone according to the first embodiment, a warning indicating that the remaining number of the telephone according to the first embodiment is low is displayed on the display unit 14, and a warning sound transmission unit is provided. The LED blinks at the same time when the warning sound is emitted from the step 15, so that the warning of the remaining frequency to the user can be more easily confirmed.

Further, as a fourth embodiment of the present invention, a timer capable of measuring a talk time is added to the telephone according to the first embodiment, and the memory unit 12 is expanded as shown in FIG. . Here, the expanded portion, the latest call time 924 to the average call time 944 in FIG. 9 is for storing the call time, the unit is seconds, and the initial value is the latest call time 924 to the average call time 944.
(Seconds).

A timer is started at the start of a call, the timer is stopped at the end of the call, the time of one call is measured, and the call is saved in the same manner as the operation of storing the consumption frequency in the first embodiment. The time is saved for 20 times from the last call to the 19th previous call. At the same time as averaging the "20" value of the consumption frequency for each call in the first embodiment, the call time of the "20" value is also averaged, and the average call time indicated by the latest call time 924 in FIG. To the save area. In the first embodiment, in the operation of reading the reference number of times from the memory unit 12 and displaying it on the display unit 14,
9 is multiplied by the value of the area of the standard number of times indicated by the standard number of calls 923 and the value of the area of the average number of call times indicated by the latest call time 924, and the remaining remaining time indicating the remaining time of the call. It is a telephone that calculates the time and displays the estimated remaining call time on the display unit 14 instead of the estimated number of times.

[0039]

As described above, according to the present invention, on the premise of use by a prepaid contract, the remaining number notified from the line network is processed, and when the remaining number becomes equal to or less than a predetermined value, the remaining number of times is processed. The approximate number of calls that can be used is determined, and the number is displayed on the display unit and at the same time a warning sound is generated from the warning sound transmission unit. The user can intuitively know how many calls are possible, so the user can add a frequency at a timing according to his / her telephone usage tendency and save telephone usage. This has the effect of making it easier.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a prepaid telephone system with a residual number warning device according to the present invention.

FIG. 2 is an explanatory diagram of storage contents such as a remaining number and a consumption number stored in a memory unit of the prepaid telephone system with a remaining number warning device of FIG. 1;

FIG. 3 is an explanatory diagram showing an example of display contents on a display unit of the prepaid-for-payment telephone set with the residual frequency warning device of FIG.

FIG. 4 is an explanatory diagram of stored contents such as a remaining number and a consumption number stored in a memory unit of “state 1” in the first embodiment of a prepaid telephone system with a remaining number warning device according to the present invention.

FIG. 5 is an explanatory diagram of stored contents such as a remaining frequency and a consumption frequency stored in the memory unit of “state 2” in the first embodiment of the prepaid telephone system with a residual frequency warning device according to the present invention.

FIG. 6 is an explanatory diagram of stored contents such as a remaining frequency and a consumption frequency stored in a memory unit of “state 3” in the first embodiment of a prepaid telephone system with a residual power warning device according to the present invention.

FIG. 7 is an explanatory diagram showing the contents of “STATE 3” finally stored in the memory unit after the end of the call in the first embodiment of the prepaid telephone system with a residual number warning device according to the present invention.

FIG. 8 is an explanatory diagram showing the contents of initial values stored in the memory unit at the first use of the prepaid telephone system with a residual number warning device according to the first embodiment of the present invention.

FIG. 9 is an explanatory diagram of storage contents such as a remaining number and a consumption number stored in a memory unit in a fourth embodiment of a prepaid telephone system with a remaining number warning device according to the present invention.

[Explanation of symbols]

10 ... line network, 10a ... phone line, 11 ... line interface unit, 12 ... memory unit, 13 ... control unit,
14 display unit, 15 warning sound transmission unit, 16 operation unit.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04M 3/00 H04M 3/16-3/20 H04M 3/38-3/40 H04M 7/00-7/16 H04M 15 / 00-17/02

Claims (15)

(57) [Claims] 1. A line interface unit connected to a telephone line connected to a line network, wherein a usable frequency based on a paid fee according to a prepaid contract is notified from the line network, a memory for storing a call frequency, Based on the remaining frequency information received at the end of the call by the line interface unit, the control unit issues a warning indicating that the remaining frequency is low when the remaining frequency of the calling frequency stored in the memory unit falls below a predetermined value. A display section for displaying a warning message as a warning message; a warning sound sending section for generating a warning sound indicating that the remaining number is low under the control of the control section at the same time as displaying the warning message on the display section; An operation unit for performing an operation, comprising: a prepaid telephone set with a residual number warning device. 2. The telephone system according to claim 1, wherein the memory unit is capable of writing and reading the value stored by the control unit at any time. 3. The prepaid telephone set with a remaining number warning device according to claim 1, wherein the stored value of the memory unit does not change even when the power is turned off, except for rewriting the value by the control unit. 4. The memory unit according to claim 1, further comprising: an area for storing a current value of the residual frequency, an area for storing a numerical value of the remaining frequency of the previous call, and a storage for storing a numerical value of the consumed frequency for each call. 4. An area according to claim 1, further comprising: an area for storing the number of times of use, and an area for storing a numerical value of the estimated number of times of use.
Prepaid phone with a residual alarm device described in the section. 5. The residual number warning according to claim 1, wherein the display unit is an LCD panel capable of displaying a multi-digit number with dots lit and an arbitrary graphic display under the control of the control unit. Prepaid phone with equipment. 6. The prepaid telephone set with a residual number warning device according to claim 1, wherein the warning sound sending unit is a buzzer that can turn on / off a warning sound by a signal from the control unit. 7. The line interface unit is connected to a telephone network of a telephone company, a control signal line, and a voice signal line, and controls transmission and reception of telephone calls to and from the line network under the control of the control unit. 2. A prepaid telephone system with a residual number warning device according to claim 1, wherein a control signal to be controlled is transmitted and received, and a voice signal is transmitted and received via a voice signal line when a call is started. 8. The prepaid telephone set with a residual number warning device according to claim 1, wherein the operation unit is constituted by a plurality of button switches and has a function of enabling basic operation as a telephone set. 9. The line network is connected to a customer database storing information on a fee prepaid by a user to a telephone carrier and a residual number subtracted by a processing unit of the line network each time the user makes a call. 2. A prepaid telephone set with a residual number warning device according to claim 1, wherein: 10. The communication system according to claim 1, wherein the line network transmits the information on the remaining number as one of the control signals to the user's telephone when the user starts and ends the call. A prepaid phone with a residual warning device. 11. The line network receives a control signal via the line interface unit when the user operates the operation unit in order to check the remaining number during standby, and receives the control signal 2. The prepaid telephone set with a residual number warning device according to claim 1, wherein information on the residual number is transmitted to the line interface unit through the telephone line in order to respond to the telephone. 12. The telephone system according to claim 1, wherein the line interface unit includes a wireless unit so as to be wirelessly connected to the line network. 13. The telephone according to claim 1, further comprising: a visual indication that the remaining number is low by the display unit; and an audible notification by the warning sound of the warning sound sending unit; 2. A prepaid telephone set with a residual number warning device according to claim 1, further comprising a display device for informing. 14. The telephone according to claim 1, further comprising a timer for counting time when a call starts, and for ending the time when the call ends, and measuring a call time in one call. Prepaid phone with residual warning device. 15. The control unit calculates the remaining talkable time by multiplying the average talk time calculated from the talk time measured by the timer by the estimated number of talkable times stored in the memory unit. 15. The prepaid telephone set with a residual number warning device according to claim 14, wherein a target call time is displayed on the display unit in place of the target number of possible calls.