WO2004040892A1

WO2004040892A1 - Billing method of flat-rate tariff based telecommunication system

Info

Publication number: WO2004040892A1
Application number: PCT/KR2002/002480
Authority: WO
Inventors: Il-Hyung Jung
Original assignee: KT Corp
Current assignee: KT Corp
Priority date: 2002-10-31
Filing date: 2002-12-30
Publication date: 2004-05-13
Anticipated expiration: 2005-04-30
Also published as: KR20040038645A; KR100443169B1; CN1723686A; AU2002359067A1

Abstract

Billing method of flat-rate tariff based telecommunication system is provided. Billing method of flat-rate tariff based telecommunication service of telecommunication service system including billing database maintaining user information and service usage history information, the method includes the steps of: a) retrieving user information and the user's service usage history information from the billing database; b) if the user is subscriber of flat-rate tariff based billing service and if the user's amount of the telecommunication service usage for current term is less than the standard amount, charging the user the standard amount; c) if the user's amount is more than the standard amount and less than the maximum amount, charging the user the user's amount, the maximum amount being the sum of the standard amount and the extra amount; and d) if the user's amount is more than the maximum amount, charging the user the maximum amount.

Description

BILLING METHOD OF FLAT-RATE TARIFF BASED TELECOMMUNICATION

SYSTEM

Technical Field

The present invention relates to a billing method of a wired/wireless telecommunication system; and, more particularly, to a billing method of a flat-rate telecommunication system.

Background Art

In a flat-rate telecommunication service, a subscriber can use a telecommunication service without time restriction at a fixed service charge. A billing system opposite to the flat-rate system is a time-rate system, where the subscriber is billed as much as the subscriber has used the telecommunication service.

The flat-rate telecommunication system has an advantage that it can relieve subscribers from the burden of telecommunication service charge by charging them a fixed amount. However, the flat-rate system has a problem that it is hard to determine a flat rate that both service provider and subscribers can accept. Conventional flat- rate billing methods do not reflect the subscriber's service usage history at all and charge all the subscribers the same flat rate for the telecommunication service, collectively.

Disclosure of Invention

It is, therefore, an object of the present invention to provide a billing method for a telecommunication service where subscribers are charged for the telecommunication service according to their service usage history just as a time-rate billing system but with reduced economical burden by billing the subscribers a flat rate which is ^' differentiated according to each subscriber. In short, the present invention takes the advantages of a typical flat-rate billing system and a time-rate billing system, and bills the subscribers a fair and reasonable service charge for their using the telecommunication system.

In accordance with one aspect of the present invention, there is provided a billing method for a flat- rate telecommunication service in a telecommunication system including a billing database for storing user information and service usage history, comprising the steps of: a) reading user information and service usage history of the user from the billing database; b) if the user is a flat-rate billing subscriber and the service charge of the current period is less than a reference rate, billing the reference rate to the user; c) if the user is a flat-rate billing subscriber and the service charge of the current period is more than the reference rate and less than a maximum rate which is a summation of the reference rate and an additional rate, billing the time- rate service charge of the current period to the user; and d) if the user is a flat-rate billing subscriber and the service charge of the current period is more than the maximum rate, billing the maximum rate to the user.

In accordance with another aspect of the present invention, there is provided a computer-readable recording medium for recording a program that implements a billing method for a flat-rate telecommunication service in a telecommunication system including a processor and a billing database for storing user information and service usage history, comprising the steps of: a) reading user information and service usage history of the user from the billing database; b) if the user is a flat-rate billing subscriber and the service charge of the current period is less than a reference rate, billing the reference rate to the user; c) if the user is a flat-rate billing subscriber and the service charge of the current period is more than the reference rate and less than a maximum rate which is a summation of the reference rate and an additional rate, billing the time-rate service charge of the current period to the user; and d) if the user is a flat-rate billing subscriber and the service charge of the current period is more than the maximum rate, billing the maximum rate to the user.

Brief Description of Drawings

The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:

Fig. 1 is a block diagram illustrating a connection of an electric switching system (ESS) centralized automatic message accounting (CAMA) system and an ESS CAMA centralized management system (CCMS) apparatus that manages the states of the CAMA system in a telecommunication system in accordance with an embodiment of the present invention;

Fig. 2 is a block diagram describing an internal process of the CCMS apparatus and the CAMA system of Fig. l;

Fig. 3 is a flowchart depicting a billing process of a flat-rate telecommunication service in a telecommunication system in accordance with an embodiment of the present invention; and

Fig. 4 is a flowchart depicting a process for determining a flat rate of a flat-rate telecommunication service in a telecommunication system in accordance with an embodiment of the present invention. Best Mode for Carrying Out the Invention

Following description exemplifies only the principles of the present invention. Even if they are not described or illustrated clearly in the present specification, one of ordinary skill in the art can embody the principles of the present invention and invent various apparatuses within the concept and scope of the present invention.

The use of the conditional terms and embodiments presented in the present specification are intended only to make the concept of the present invention understood, and they are not limited to the embodiments and conditions mentioned in the specification.

The detailed description on the principles, viewpoints and embodiments and particular embodiments of the present invention should be all understood to include the structural and functional equivalents to them. The equivalents include not only currently known equivalents but also those to be developed in future, that is, all devices invented to perform the same function, regardless of their structures.

For example, block diagrams of the present invention should be understood to show a conceptual viewpoint of an exemplary circuit that embodies the principles of the present invention. Similarly, all the flow charts, state conversion diagrams, pseudo codes and the like can be expressed substantially in a computer-readable medium, and whether or not a computer or a processor is described distinctively, they should be understood to express a process operated by a computer or a processor.

The functions of various devices illustrated in the drawings including a functional block expressed as a processor or a similar concept can be provided not only by using dedicated hardware, but also by using hardware capable of running proper software. When the function is provided by a processor, the function may be provided by a single dedicated processor, single shared processor, or a plurality of individual processors, part of which can be shared.

The apparent use of a term, ^processor' , control' or similar concept, should not be understood to refer to exclusively the hardware capable of running software, but should be understood to include a digital signal processor (DSP) , hardware, and ROM, RAM and non-volatile memory for storing software, implicatively. Other known and commonly used hardware may be included therein, too.

Similarly, switches illustrated in the drawings may be presented conceptually only. The operation of the switches should be understood to be controlled by a program logic, a program through a dedicated logic, or interaction between dedicated logics, or manually. A particular technology can be selected by a designer and described to better describe the present invention.

In the claims of the present specification, an element expressed as a means for performing a function described in the detailed description is intended to include all the methods for performing the function including all formats of software, such as a combination of circuits that performs the function, firmware/microcode, and the like. To perform the intended function, the element is cooperated with a proper circuit for performing the software. The present invention defined by claims includes diverse means for performing particular functions, and the means are connected to each other in a method requested in the claims. Therefore, any means that can provide the function should be understood to be an equivalent to what is figured out from the present specification.

Other objects and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter. The same reference numeral is given to the same element, although the element appears in different drawings. In addition, if further detailed description on the related prior arts is determined to blur the point of the present invention, the description is omitted. Hereafter, preferred embodiments of the present invention will be described in detail.

In accordance with an embodiment of the present invention, an electric switching system (ESS) centralized automatic massage accounting (CAMA) is described, herein. The ESS CAMA is managed by an ESS CAMA centralized management system (CCMS) . A CAMA system of the present invention includes: a Billing Processing Device of Exchange (BPDE) for extracting charge data from an ESS and transmitting the extracted charge data to a host collector; and the host collector for collecting and verifying the charge data and transmitting them to an integrated client information system (ICIS) or a prebilling system.

The BPDE can be categorized according to the type of ESS which extracts charge data. Recently introduced ESSs, such as S1240, M10CN, N01A, 5ESS (Classic) and the like do not have the function of CAMA. The ESSs that are introduced and used include an extraction device (ED) and a transmission device (TD) . The extraction device extracts charge data and the transmission device transmits and manages charge data. The two devices, the extraction device and the transmission device, are called a billing mediation device (BMD) , collectively.

Another type of BPDE is a TDX-1 Software Modification and Administration for Remote TDX (SMART) . The SMART extracts and transmits charge data of the TDX-1A/1B/CPS. Yet another type of BPDE is a charge data transmitter (CDT) . The charge data extracted in the above-described system are transmitted to the host collector through a duplicated X.25 link to secure reliability, when the CDT is cooperated with an operation management network (OMN) . Meanwhile, new ESSs with the functions of charge extraction and charge transmission, which is a function of CAMA, installed therein are connected to the host collector, directly. Referring to Fig. 1, structures of the CAMA system and the CCMS are described. The CCMS manages the state of the CAMA system. The CAMA system includes: ESSs 1; an ESS 4 of TDX-1 series; an ESS 6 of TDX-10A; a CAMA system; a CCMS apparatus; and a new ESS 13. The CAMA system is connected to the ESS 1, the ESS 4 of TDX-1 series and the ESS 6 of TDX-10, and performs billing process and management. The CCMS apparatus is connected to the CAMA system and detects the state and errors of the CAMA system. The new ESS 13 is connected to the host collector 9 directly through the OMN 8 in the CAMA system and transmits the charge data.

The CAMA system, which is connected to the ESS 1, includes: extraction devices (ED) 2, transmission devices (TD) 3, a SMART 5 for ESS of TDX-1 series, a charge data transmitter (CDT) 7 for TDX-10 ESS, an operation management network (OMN) 8, a host collector (HC) 9 and an integrated client information system (ICIS) 10.

The extraction devices 2 are connected to the ESS 1 and extract charge data generated in the ESS 1. The transmission devices 3 administrate the charge data extracted in the extraction device 2 and transmit the charge data to the OMN 8.

The SMART 5 for ESS of TDX-1 series is connected to the ESS 4 of TDX-1 series, extracts the charge data generated in the ESS 4 of TDX-1 series, transmits the extracted charge data to the OMN 8 and manages the charge data. The CDT 7 for TDX-10 ESS is connected to the ESS 6 of TDX-10A, extracts the charge data generated in the ESS 6 of TDX-10A, transmits the extracted charge data to the OMN 8 and manages the charge data.

The OMN 8 is connected to the transmission devices 3, the SMART 5 for ESS of TDX-1 series and the CDT 7 for TDX- 10 ESS. The host collector 9 collects and verifies the charge data transmitted from the OMN 8. The integrated client information system (ICIS) 10 manages the charge data verified in the host collector 9, and calculates the exact amount of service charge. So, the integrated client information system 10 includes a service charge database for storing service usage information, which includes subscriber information, service use time, and charge information.

The CCMS apparatus includes a CCMS server 11 and CCMS clients 12. The CCMS server 11 is connected to the OMN 8, detects alarms and messages related to the status of the CAMA system generated in the transmission devices 3, the SMART 5 for the ESS of TDX-1 series and the CDT 7 for TDX- 10 ESS and the host collector 9, and stores them. The CCMS clients 12 allow operators to monitor the messages stored in the CCMS server 11. The extraction devices 2 and the transmission devices 3 are referred to as BPDE, collectively. The SMART 5 for ESS of TDX-1 series and the CDT 7 for TDX-10 ESS are types of the BPDE.

In a wired telecommunications system of the present invention, the CCMS server 11 of the CCMS apparatus uses workstation-class hardware, and the CCMS clients 12 use personal computer (PC) -class hardware. To describe how the CAMA system and the CCMS apparatus are operated, the charge data for telecommunication services generated in the ESS 1 are extracted in the extraction devices 2 for ESS, and then transmitted to the host collector 9 through the transmission device 3 for ESS. The host collector 9 collects information on the charge data and the status of the ESS and verifies them.

The ESS 4 of TDX-1 series transmits the information on the charge data and the status of the ESS 4 to the host collector 9 through the SMART 5 for ESS of TDX-1 series. The ESS 6 of TDX-10 transmits them to the host collector 9 through the CDT 7 for TDX-10 ESS. The host collector 9 receives, manages and verifies the charge data and the status data, and then it transmits the charge data to the integrated client information system 10. Here, an integrated client information system or prebilling system is used.

To manage the CAMA system processed as described above, the CCMS server 11 collects information on the state and statistics of the CAMA system, processes, stores and manages the collected information, computes statistics, and displays them on the monitor screen of the operator. Then the operator accesses his CCMS client 12 to the CCMS server 11 by using a web browser and monitors the status of the CAMA system frequently. Here, in the CCMS server 11 and the CCMS client 12, different menus appear according to the grade of the subscriber, when the subscriber accesses to the CCMS server 11 without difference in operation. When the subscriber accesses to the CCMS server 11 with a grade of an operator, the subscriber cannot process or change information in the Transmission Control Protocol-Internet Protocol (TCP/IP) . The subscriber can read information according to the type of BPDE only. If the subscriber accesses to the CCMS server 11 with a grade of administrator, the subscriber can change or delete data in the system.

As shown from the above, if the operator could monitor the status of the CAMA system, it is possible to cope with errors quickly because he or she can determine what error has occurred in the current CAMA system.

The telecommunication system includes a CAMA system that is managed by the CCMS apparatus in accordance with an embodiment of the present invention. It is obvious to those skilled in the art that the structure of the telecommunication system described in Fig. 1 can be changed variously by a system designer, and that it can be applied to a wireless telecommunication service as well as a wired telecommunication service. Therefore, the present invention is not limited to the structure of the CAMA system which is managed by the CCMA apparatus. Fig. 2 is a block diagram describing the internal process of the CAMA system and the CCMS apparatus of Fig. 1. The CCMS server 11 is connected to the CCMS clients 12 through a local area network (LAN) interface 14, and the CCMS server 11, the BPDE (A) and the host collector 9 are connected through the OMN 8 to each other.

The CCMS server 11 includes: a starting unit 111, an information collecting client 112, an information collecting server 113, an information transmitting client 114, a client server information distributing unit 115, an information transmitting server 116 and a server user graphic interface unit 117.

The starting unit 111 outputs an alarm-based restoration message and a state information requesting message to collect information on the state of the CAMA system, when the CCMS server 11 begins operation. The information collecting client 112 transmits the state information requesting message transmitted from the starting unit 111 to the host collector 9.

The information collecting server 113 receives information on the state of the CAMA system, information on the state of charge data collection, information on the state of transmitting a charge file, and alarms from the transmission devices 3, the SMART 5 for ESS of TDX-1 series and the CDT 7 for TDX-10 ESS of the CAMA system, collects information on the state of a system and alarms from the host collector 9, and transmits them to the information transmitting client 114.

The information transmitting client 114 receives the BPDE alarm, the host collector alarm and the CCMS apparatus alarm from the information collecting server 113 and transmits them to the client server information distributing unit 115. The client server information distributing unit 115 distributes the alarm message and the information on SCM which are transmitted from the information transmission client 114 to the server user graphic interface unit 117, the CCMS clients 12, and the information transmitting server 116, respectively.

The information transmitting server 116 transmits the information transmitted from the client server information distributing unit 115 to the information collecting client 112. The server user graphic interface unit 117 connects the operator to the CCMS server 11.

The CCMS client 12 is connected to the client server information distributing unit 115 through a LAN interface 14, and it includes a client user graphic interface unit 121.

The BPDE (A) includes a billing information transmitting server (Al) , a billing information transmitting client (A2) , and a billing file transmitting unit (A3) . The billing information transmitting server (Al) collects the state information requesting message and a CCMS shape requesting message from the information collecting client 112 in the CCMS server 11, and if the collected message is a state information requesting message, the billing information transmitting server (Al) transmits it to the billing information transmitting client (A2) , or if the collected message is a CCMS shape requesting message, the billing information transmitting server (Al) transmits it to the billing file transmitting unit (A3) . Then, if the billing information transmitting server Al receives an acknowledgement message of the message it has transmitted, it transmits the acknowledgement message to the CCMS server 12.

The billing information transmitting client (A2) transmits a state information message in response to the state information requesting message which is transmitted from the billing information transmitting server (Al) . The billing file transmitting unit (A3) transmits an acknowledgement message in response to the CCMS shape requesting message which is transmitted to the billing information transmitting server (Al) . The host collector 9 includes a charge collecting and processing unit 91, a charge collection checking unit 92, and a charge collecting and transmitting unit 93. The charge collecting and processing unit 91 collects the state information requesting message transmitted from the information collecting client 112 in the CCMS server 11 and transmits it to the charge collection checking unit 92.

When the charge collection checking unit 92 receives the state information requesting message from the charge collecting and processing unit 91, it checks the state of the host collector 9 and outputs messages corresponding to an alarm from the host collector 9 and a response message on the state to the charge collecting and transmitting unit 93. The charge collecting and transmitting unit 93 receives the acknowledgement message from the charge collection checking unit 92 and transmits it to the CCMS server 11.

Hereinafter, the cooperation of the CAMA system and the CCMS apparatus which are formed as above is described. First, when the CCMS server 11 begins operating, it transmits an alarm-based restoration message and a state information requesting message to the information transmitting client 114 and the information collecting client 112, respectively. Then, the information collecting server 113 receives information on the state of a system, information on the state of charge data collection, information on the state of billing file transmission and alarms from the BPDE (A) through an X.25 network. It collects information on the state of system and alarms from the host collector 9 and transmits them to the information transmitting client 114.

Meanwhile, the BPDE (A) receives the state and shape requesting messages and collects and processes information corresponding to the messages from the billing information transmitting client (A2) and billing file transmitting unit (A3) , and then transmits the result to the information collecting server 113 through the billing information transmitting server (Al) .

If the host collector 9 receives the state information requesting message, it collects an acknowledge message from the charge collection checking unit 92 and transmits it to the information collecting server 113.

When the information collecting server 113 collects all information, the information transmitting client 114 receives the BPDE alarm, the host collector alarm and the CCMS apparatus alarm, which are collected in the information collecting server 113, and transmits them to the client server information distributing unit 115.

The client server information distributing unit 115 divides and transmits the information to the server user graphic interface unit 117, the CCMS client 12 and the information transmitting server 116. The information transmitting server 116 transmits the received messages to the information collecting client 112.

Fig. 3 is a flow chart illustrating a billing process of a flat-rate telecommunication serve in accordance with an embodiment of the present invention. A telecommunication service provider charges its service subscribers for the telecommunication service in the following process.

At step S301, billing information of a user is read out of a billing database. At step S303, it is checked whether the user is a flat-rate subscriber. At step S305, if the user is not a flat-rate subscriber, the user is an ordinary time-rate subscriber. Thus ordinary time-rate billing process is performed for the user. At step S307, if the user turns out to be a flat-rate subscriber at the step S303, it is checked that his/her service charge of the current month is not more than a reference rate. The reference rate is a statistically obtained representative value of the service charges the user has paid for the telecommunication service. For example, an average of the service charges for a predetermined period can be the reference rate.

At step S309, if the service charge of the current month is less than the reference rate, the reference rate is charged to the user. The purpose of the flat-rate telecommunication service of the present invention is to secure the service provider a minimum of the reference rate. Although the subscriber uses the telecommunication service for a time shorter than a time corresponding to the amount of the reference rate, he should pay as much as the reference rate.

If the service charge of the current month is more than the reference amount at the step S307, at step S311, it is checked whether the service charge is less than a maximum amount which is obtained by summating the reference rate and an additional rate (maximum amount = reference rate + additional rate) . The flat-rate subscriber pays the additional rate to use the flat-rate service, other than the reference rate. It is calculated based on the reference rate. For example, if the user subscribes a flat-rate local call service, his/her reference rate is obtained by calculating an average amount of the service charges the subscriber has paid for a predetermined period. Then, the additional rate is determined in a way if the reference rate is less than 10,000 won, the additional rate is 1,000 won, and when the reference rate is more than 10,000 and less than 20,000 ([1 thousand won, 2 thousand won]), it becomes 2,000 won.

At step S313, where if the service charge of the current month is less than the maximum rate, the service charge of the current month is charged. That is, the time-rate billing process is performed for the service the flat-rate subscriber has used within the range of [reference rate, maximum rate] in the embodiment of the present invention. Meanwhile, in case where the service charge of the current month is more than the maximum rate at the step S311, the maximum rate is charged. That is, typical flat- rate billing is performed by charging the maximum rate in the embodiment of the present invention. In this case, the telecommunication service provider can secure at least the average of the service charges the subscriber has paid before. On the other hand, the subscriber pays as much as he/she has used in the range of [reference rate, maximum rate] . Accordingly, the unfairness of the conventional flat-rate billing system where the same flat rate is applied to all users collectively can be solved. In the range where the service charge of the current month exceeds the maximum rate, the subscriber pays the maximum rate in the typical flat-rate method. Therefore, the method of the present invention takes the advantages of the conventional flat- rate billing system and the time-rate billing system.

Fig. 4 is a flowchart depicting a process for determining a fixed rate of a flat-rate telecommunication service in a telecommunication system in accordance with an embodiment of the present invention. When a telecommunication service subscriber applies for the flat rate billing, at step S401, user information is read out of the billing database and, at step S403, it is determined whether the subscriber is a new subscriber for the flat rate billing service, or an applicant for update.

If the subscriber turns out to be a new subscriber at the step S403, at step S405, a statistically obtained representative value of the previous service charges is calculated and determined as a reference rate to be billed. An average or a mid-point value may be used as the statistically obtained representative value. For example, if an average value is used as the statistically obtained representative value, the monthly average of the service charges the subscriber has paid for a predetermined period, e.g., recent one year, can be the representative value.

Subsequently, at step S407, an additional rate to be charged to the subscriber is determined based on the reference rate. The maximum rate that can be charged to the subscriber is the summation of the reference rate and the additional rate.

The additional rate can be established in various ways. For example, it can be determined in proportion or inverse proportion to the reference rate, which is shown in Table 1 or 2 below.

Table 1

Based on the reference rate, the additional rate and the maximum rate, the flat rate billing is performed through the process of Fig. 3.

If the subscriber turns out to be applying for update

(an i^th update subscriber, i being an integer and i ≥ l ) for an i^th service period, at step S409, the reference rate, the additional rate and the maximum rate are established for the i^th update subscriber.

In the present invention, the flat rate billing service is provided for a predetermined period, for example, one year. The flat rate billing service subscriber can update his/her subscription. In an i^th service period, if i is zero ( t = 0 ) , it means that it is a period the subscriber subscribes the telecommunication service at a flat rate billing service subscriber for the first time. The reference rate for the i^th update subscriber can be determined in various methods. For example, it can be determined by calculating the statistically obtained representative value from the service charges billed to the i^th subscriber for an i-l^th service period. An average or a mid-point value can be used as the statistically obtained representative value. If an average is used as a statistically obtained representative value, the time-rate monthly average the subscriber has paid for an i-l^th service period may become the statistically obtained representative value.

For another example, the time-rate monthly average during the i-l^th service period or the largest service charge of the i-l^th service period may be determined as the reference rate. In other words, if the monthly average of the time-rate service charges the i^th update subscriber has paid for an i-l^th service period lies in the range of [0, maximum rate] , the reference rate of the i-l^th service period or the monthly average of the service charges calculated in the time-rate billing method during the i-l^th service period becomes the reference rate of the i^th service period. .If the monthly average of the service charges calculated in the time-rate method during an i-l^th service period is in the range of [maximum rate, ∞] , the maximum rate of the i-l^th service period is determined as the reference rate for the i^th service period.

The additional rate for the i^th update subscriber can be determined variously. For example, it can be determined in proportion or inverse proportion to the reference rate, which is shown in Table 3 or 4.

Table 3

For another example, the monthly average of the i^th update subscriber calculated in the time-rate billing method during the i-l^th service period or the reference rate during the i-l^th service period may be determined as a reference. Additional rate for an i^ft service period = Additional rate for an i-l* service period Minute - rate monthly average for (i -1)* service period Reference -rate for (i -l)* service period

Equation 1

When the additional rate is determined, the maximum rate that can be billed to the i^th update subscriber is the summation of the reference rate and the additional rate. Based on the reference rate, the additional rate and the maximum rate, billing process is performed for the i^th update subscriber as illustrated in Fig. 3.

The billing method of the present invention described above can be embodied as a program and stored in a computer-readable recording medium, such as CD-ROMs, RAMs, ROMs, floppy disks, hard disks, magneto-optical disks and the like.

While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

Claims

What is claimed is:

1. A , billing method for a flat-rate telecommunication service in a telecommunication system including a billing database for storing user information and service usage history, comprising the steps of: a) reading user information and service usage history of the user from the billing database; b) if the user is a flat-rate billing subscriber and the service charge of the current period is less than a reference rate, billing the reference rate to the user; c) if the user is a flat-rate billing subscriber and the service charge of the current period is more than the reference rate and less than a maximum rate which is a summation of the reference rate and an additional rate, billing the time-rate service charge of the current period to the user; and d) if the user is a flat-rate billing subscriber and the service charge of the current period is more than the maximum rate, billing the maximum rate to the user.

2. The method as recited in claim 1, wherein the reference rate is a statistically obtained representative value of telecommunication service charges the user has paid for a predetermined period.

3. The method as recited in claim 1, wherein the additional rate is calculated based on the reference rate.

4. The method as recited in any one of claims 1 to 3, wherein the reference rate is a monthly average of service charges the user has paid for a predetermined period.

5. The method as recited in any one of claims 1 to 3, wherein the reference rate for an i^th service period of an i^th update subscriber is determined based on the monthly average of an i-l^th service period calculated in a time- rate method and the maximum rate of the i-l^th service period, i being an integer and equal to or larger than 1 ( i ≥ l ) .

6. The method as recited in claim 5, wherein if the monthly average of time-rate service charges the i^th update subscriber has paid for an i-l^h service period is in the range of [0, maximum rate] of the i-l^th service period, the reference rate for an i^th service period is the reference rate of the i-l^th service period or the monthly average of the i-l^th service period calculated in a time- rate method.

7. The method as recited in claim 5, wherein if the monthly average of time-rate service charges the i^th update subscriber has paid for an i-l^th service period is in the range of [maximum rate, ∞] of the i-l^th service period, the reference rate for an i^th service period is the maximum rate of the i-l^th service period.

8. The method as recited in any one of claims 1 to 3, wherein the additional rate is determined in proportion to the reference rate.

9. The method as recited in any one of claims 1 to 3, wherein the additional rate is determined in inverse proportion to the reference rate.

10. The method as recited in any one of claims 1 to 3, wherein the additional rate for an i^th service period is determined based on the monthly average of time-rate service charges an i^th update subscriber has paid for an i- 1^th service period and the reference rate of the i-l^th service period, which is shown in an equation expressed as :

Additional rate for an i^th service period = Additional rate for an i-l service period X Minute - rate monthly average for (i -l) "* service period Reference -rate for (i -l)⁴ service period

11. A billing method for a flat-rate telecommunication service in a telecommunication system including a billing database for storing user information and service usage history, comprising the steps of: a) registering a subscriber using the flat-rate telecommunication service; b) determining a reference rate or an additional rate to bill to the subscriber; and c) billing the service charge of the flat-rate telecommunication service to the subscriber based on the reference rate or additional rate.

12. The method as recited in claim 11, wherein the reference rate is a statistically obtained representative value of telecommunication service charges the user has paid for a predetermined period.

13. The method as recited in claim 11, wherein the additional rate is calculated based on the reference rate.

14. The method as recited in any one of claims 11 to 13, wherein the reference rate is a monthly average of service charges the user has paid for a predetermined period.

15. The method as recited in any one of claims 11 to 13, wherein the reference rate for an i^th service period of an i^th update subscriber is determined based on the monthly average of time-rate service charges the i^th update subscriber has paid for an i-l^th service period and the maximum rate of the i-l^th service period, i being an integer and equal to or larger than 1 (z≥l).

16. The method as recited in claim 15, wherein if the monthly average of time-rate service charges the i^th update subscriber has paid for an i-l^th service period is in the range of [0, maximum rate] of the i-l^th service period, the reference rate for the i^th service period is the reference rate of the i-l^th service period or the monthly average of an i-l^th service period calculated in the time-rate method.

17. The method as recited in claim 15, wherein if the monthly average of time-rate service charges the i^th update subscriber has paid for an i-l^th service period is in the range of [maximum rate, °°] of the i-l^th service period, the reference rate for the i^th service period is the maximum rate of the i-l^th service period.

18. The method as recited in any one of claims 11 to 13, wherein the additional rate is determined in proportion to the reference rate.

19. The method as recited in any • one of claims 11 to 13, wherein the additional rate is determined in inverse proportion to the reference rate.

20. The method as recited in any one of claims 11 to 13, wherein the additional rate for an i^th service period is determined based on the monthly average of time- rate service charges the i^th subscriber has paid for an i- 1^th service period and the reference rate of the i-l^th service period, which is shown in an equation expressed as : Additional rate for an i^th service period = Additional rate for an i-l* service period x Minute -rate monthly average for (i -l)"¹ service period Reference - rate for (i -l)*¹¹ service period

21. The method as recited in any one of claims 11 to 13, wherein the step c) includes the steps of: cl) reading user information and service usage history of the user from the billing database; c2) if the service charge of the current billing period is less than the reference rate, billing the reference rate to the subscriber; c3) if the service charge of the current billing period is more than the reference rate and less than a maximum rate which is a summation of the reference rate and the additional rate, billing the time-rate service charge of the current billing period to the subscriber; and c4) if the service charge of the current billing period is more than the maximum rate, billing the maximum rate to the subscriber.

22. A computer-readable recording medium for recording a program that implements a billing method for a flat-rate telecommunication service in a telecommunication system including a processor and a billing database for storing user information and service usage history, comprising the steps of: a) reading user information and service usage history of the user from the billing database; b) if the user is a flat-rate billing subscriber and the service charge of the current period is less than a reference rate, billing the reference rate to the user; c) if the user is a flat-rate billing subscriber and the service charge of the current period is more than the reference rate and less than a maximum rate which is a summation of the reference rate and an additional rate, billing the time-rate service charge of the current period to the user; and d) if the user is a flat-rate billing subscriber and the service charge of the current period is more than the maximum rate, billing the maximum rate to the user.