Abstract:
A method for re-rating a prepaid user is proposed in the present invention. Compared with prior prepaid systems, the present invention introduces new functional entities, i.e. a re-rating management apparatus and an offline charging apparatus, and enhances the existing functional-entity, i.e. the online charging apparatus. The online charging apparatus rates call detail records comprised in an received online charging request to generate rated call detail records, and sends—the rated call detail records to the re-rating management apparatus; periodically backs up account profile, and sends the backed up account profile to the re-rating management apparatus; the re-rating management apparatus triggers re-rating, sends a re-rating request to the offline charging apparatus; the offline charging apparatus generates re-rated call detail records after re-calculating, the call detail records, and sends the re-rated call detail records to the re-rating management apparatus; and the re-rating management apparatus updates account profile in accordance with the re-rated call detail records, and sends the updated account profile to the online charging apparatus. By using the method of the present invention, the re-rating function can be implemented for the prepaid user without affecting the real-time use by the prepaid user, and the problems occurring in the convergence of a prepaid charging system and a postpaid charging system can be solved.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a communication network, and more particularly to a processing method and apparatus for re-rating in the communication network. 
     BACKGROUND OF THE INVENTION 
     Currently, most operators need to maintain two separated charging systems, i.e. an IT based postpaid charging system and an intelligent-networks based prepaid charging system. The postpaid charging system employs an offline charging manner, and it periodically collects Call Detail Records (CDRs) over network, determines the expense for a call according to the information (e.g. the call duration for a user, caller information, callee information, position information, etc.) included in the call detail record, and determines the tariff based on the call detail record after the call. Therefore it is impossible to achieve a real-time control for a user&#39;s call. The prepaid charging system employs an online charging manner, and it determines in real time a duration for a user to make a call in accordance with the balance of the user&#39;s account. When the user runs out of the balance of his account, the call will be cut off immediately. The prepaid charging system needs to monitor and control the call of the user in real time. 
     For an operator, maintaining two charging systems means a high cost and furthermore some functionalities of one system cannot be implemented or cannot be implemented well in the other system. For example, re-rating is a functionality of the postpaid charging system, which can re-rate the expense for the call detail record in accordance with changes of the service price. However, it is difficult for the real-time prepaid charging system to realize re-rating because the prepaid charging system needs to monitor a user&#39;s call request in real time and to update the user&#39;s account profile in real time and cannot make recalculation on the user&#39;s account profile as if it was rolled back to a previous stage. Specifically, for the prepaid charging system, before each call is established, the system will read the user&#39;s account profile, and if the account profile is updated at this time, it is impossible for the system to read the current account profile for the current call request or read a wrong account profile. 
     More and more operators and market analyzers recognize that a charging system converging both the postpaid charging system and the prepaid charging system will be the future developing trend, and such a converged charging system not only can reduce the cost but also can provide users with blended services. Most operators urgently demand such converged charging system provided by the vendors. 
     However, as stated above, re-rating is a functionality of the postpaid charging system and it is difficult to be implemented in the prepaid charging system. How to implement the re-rating function for the converged charging system will be a challenge. Thus, an approach to implement the re-rating function for the prepaid charging system is needed. 
     SUMMARY OF THE INVENTION 
     In order to solve the above problems in the prior art, a method and an apparatus for re-rating prepaid users is proposed in the present invention. 
     According to a first aspect of the present invention, a method for re-rating a prepaid user implemented in a first apparatus ( 2   a ) is provided, the method including: rating a call detail record included in a received online charging request to generate a rated call detail record, and updating account profile of the user at the same time; and sending to a second apparatus ( 2   b ) a rating information transmission request message including the rated call detail record; 
     the method further including: periodically storing the account profile, and sending to the second apparatus ( 2   b ) an account profile transmission request message including the stored account profile; 
     the method further including: updating the locally stored account profile in accordance with the updated account profile included in an account profile update request received from the second apparatus ( 2   b ). 
     According to a second aspect of the present invention, a method for re-rating a prepaid user implemented in a second apparatus ( 2   b ) is provided, the method including: receiving from a first apparatus ( 2   a ) a rating information transmission request message including a rated call detail record, and extracting the rated call detail record; receiving from the first apparatus ( 2   a ) an account profile transmission request message including an account profile, and extracting the account profile; 
     the method further including: triggering re-rating and determining a re-rating rule; a re-calculating step for generating a re-rated call detail record in accordance with the re-rating rule; and updating a corresponding account profile in accordance with the re-rated call detail record, and sending to the first apparatus ( 2   a ) an account profile update request including the updated account profile. 
     Preferably, the re-calculating step further includes: determining a start point of re-rating, updating the account profile for the start point of re-rating in accordance with the re-rating rule, and sending to a third apparatus ( 2   c ) a start point account profile transmission request including the updated account profile for the start point of re-rating; determining call detail records to be re-rated; sending to the third apparatus ( 2   c ) a re-rating request message including one or more call detail records to be re-rated; and receiving from the third apparatus ( 2   c ) a re-rating reply message including one or more re-rated call detail records. 
     According to a third aspect of the present invention, a method for re-rating a prepaid user implemented in a third apparatus ( 2   c ) is provided, the method including: receiving from a second apparatus ( 2   b ) a start point account profile transmission request including the updated account profile for a start point of re-rating, and extracting a rating rule for re-rating therefrom; receiving from the second apparatus ( 2   b ) a re-rating request including one or more call detail records to be re-rated, and extracting the call detail records to be re-rated; re-rating the call detail records to be re-calculated in accordance with the rating rule for the re-rating to generate re-rated call detail records; and sending to the second apparatus ( 2   b ) a re-rating reply message including one or more re-rated call detail records. 
     According to a fourth aspect of the present invention, a first apparatus ( 2   a ) for re-rating a prepaid user is provided, the apparatus including: a rating means configured to rate call detail records included in a received online charging request to generate rated call detail records and to update account profile of the user at the same time; and a rating information transmitting means configured to send to a second apparatus ( 2   b ) a rating information transmission request message including the rated call detail records; 
     the apparatus further including: an account backing up means configured to periodically store the account profile, and to send to the second apparatus ( 2   b ) an account profile transmission request message including the stored account profile; 
     the apparatus further including: a first account updating means configured to update the locally stored account profile in accordance with the updated account profile included in an account profile update request received from the second apparatus ( 2   b ). 
     According to a fifth aspect of the present invention, a second apparatus ( 2   b ) for re-rating a prepaid user is provided, the apparatus including: a rating information receiving means configured to receive from a first apparatus ( 2   a ) a rating information transmission request message including rated call detail records, and to extract the rated call detail records; and an account profile receiving means configured to receive from the first apparatus ( 2   a ) an account profile transmission request message including account profile, and to extract the account profile; 
     the apparatus further including: a triggering means configured to trigger re-rating and to determine a re-rating rule; a re-calculating means configured to generate re-rated call detail records in accordance with the re-rating rule; and a second account updating means configured to update a corresponding account profile in accordance with the re-rated call detail records, and to send to the first apparatus ( 2   a ) an account profile update request including the updated account profile. 
     Preferably, the re-calculating means further includes: a start point account updating means configure to determine the start point of re-rating and to update the account profile for the start point of re-rating in accordance with the re-rating rule, and to send to a third apparatus ( 2   c ) a start point account profile transmission request including the updated account profile for the start point of re-rating; a determining means configured to determine call detail records to be re-rated; a re-rating request sending means configured to send to the third apparatus ( 2   c ) a re-rating request message including one or more call detail records to be re-rated; and a re-rating reply receiving means configured to receive from the third apparatus ( 2   c ) a re-rating reply message including one or more re-rated call detail records. 
     According to a sixth aspect of the present invention, a third apparatus ( 2   c ) for re-rating a prepaid user is provided, the apparatus including: a start point account profile receiving means configured to receive from a second apparatus ( 2   b ) a start point account profile transmission request including the updated account profile for a start point of re-rating, and to extract a rating rule for re-rating therefrom; a re-rating request receiving means configured to receive from the second apparatus ( 2   b ) a re-rating request including one or more call detail records to be re-rated, and to extract the call detail records to be re-rated; a re-rated record generating means configured to re-rate the call detail records to be re-rated in accordance with a rating rule for re-rating to generate re-rated call detail records; and a re-rating reply sending means configured to send to the second apparatus ( 2   b ) a re-rating reply message including one or more re-rated call detail records. 
     According to a seventh aspect of the present invention, a system for re-rating a prepaid user is provided, including: the aforesaid first apparatus ( 2   a ), the aforesaid second apparatus ( 2   b ) and the aforesaid third apparatus ( 2   c ). 
     By using the method and apparatus of the present invention, the re-rating function can be implemented for prepaid users without affecting the real-time use by the prepaid users. Thus, operators may converge the prepaid charging system and the postpaid charging system into one charging system, which not only can efficiently reduce operators&#39; operation and maintenance cost but also can provide users with unified blended services, wherein the same charging function can be applicable to both prepaid users and postpaid users at the same time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features, objects and advantages of the present invention will become more apparent with reference to the following detailed description to the nonrestrictive embodiments in conjunction with the accompanying drawings. 
         FIG. 1  is a schematic diagram of a prepaid charging system in the prior art. 
         FIG. 2  is a flowchart illustrating the re-rating for prepaid users according to a specific embodiment of the present invention. 
         FIG. 3  is a block diagram illustrating the structure of an online charging apparatus according to a specific embodiment of the present invention. 
         FIG. 4  is a block diagram illustrating the structure of a re-rating management apparatus according to a specific embodiment of the present invention. 
         FIG. 5  is a block diagram illustrating the structure of an offline charging apparatus according to a specific embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Firstly, explanations are made to the following concepts used in this text: 
     Call Detail Record (CDR) refers to information related to a certain call, at least including information such as calling and called numbers, call date, call time and call duration. 
     Rated call detail record refers to the expense information of a certain call calculated in accordance with the call detail record of the call and the current rating rule, at least including information such as calling and called numbers, call date, call time, call duration and call expense of the call. 
     Re-rated call detail record refers to the expense information of a certain call recalculated in accordance with the call detail record of the call and the rating rule for re-rating, at least including information such as calling and called numbers, call date, call time, call duration and recalculated call expense of the call. 
     Account profile refers to information related to an account of a prepaid user, at least including the current balance of the account and the rating rule for the subscribed telecommunication service. 
       FIG. 1  illustrates a schematic diagram of a charging system for charging a prepaid user in the prior art. Network  101  sends an online charging request to an online charging apparatus  1   a . The online charging apparatus  1   a  extracts the information related to the caller and callee in the call detail record included in the online charging request to determine the corresponding account, and obtains corresponding account profile by searching the locally stored database to further obtain the current balance of the account. The online charging apparatus  1   a  will further extract the information related to the call in the call detail record included in the online charging request, and then rate the call in accordance with the current rating rule to generate a rated call detail record, and update the locally stored account profile in accordance with the information related to the call expense in the rated call detail record at the same time. 
     It can be seen that, since the prepaid charging system needs to update account profile in real time, the re-rating function cannot be implemented. For example, if the current date is February 15, then the balance in the current account profile is the balance at the current time on February 15. When it is necessary to re-rate the calls from 0 am on February 2 to the current time on February 15 in accordance with a new rating rule, the system needs the balance of the account of 0 am on February 2, but this information cannot be obtained from the current system. 
     Thus, to solve the above problem, an approach for re-rating for prepaid users is proposed in the present invention. In the following, the method will be described in more detail with reference to  FIG. 2 . 
       FIG. 2  illustrates a flowchart of the re-rating for prepaid users according to a specific embodiment of the present invention. Seen from  FIG. 2 , the prepaid charging system of the present invention at least includes an online charging apparatus  2   a , a re-rating management apparatus  2   b  and an offline charging apparatus  2   c.    
     Here, the online charging apparatus  2   a , the re-rating management apparatus  2   b  and the offline charging apparatus  2   c  are all functional entities, and they may exist in a same network server or in different network servers. For example, the online charging apparatus  2   a , the re-rating management apparatus  2   b  and the offline charging apparatus  2   c  may respectively exist in three different network servers; or the online charging apparatus  2   a  exists in one network server while the re-rating management apparatus  2   b  and the offline charging apparatus  2   c  exist in another network server; or the online charging apparatus  2   a , the re-rating management apparatus  2   b  and the offline charging apparatus  2   c  exist in a same network server. 
     Compared with  FIG. 1 , the re-rating management apparatus  2   b  and the offline charging apparatus  2   c  are both newly added functional entities while the online charging apparatus  2   a  has additional functions with respect to the existing online charging apparatus  1   a.    
     The method starts at Step S 201  where the online charging apparatus  2   a  receives an online charging request from Network  201 , and the online charging request includes detailed information of a call to be rated. For this request, the online charging apparatus  2   a  will execute the following actions:
         the online charging apparatus  2   a  rates the call detail record included in the online charging request to generate a rated call detail record, e.g. obtaining the call expense in accordance with the current rating rule and the call duration included in the call detail record, and then updating the user&#39;s account profile in accordance with the expense caused by the call and the current balance of the account corresponding to the call;   the online charging apparatus  2   a  sends a rating information transmission request to the re-rating management apparatus  2   b , as shown in Step S 202  of  FIG. 2 , wherein the rating information transmission request includes the generated rated call detail record.       

     In addition, the online charging apparatus  2   a  will periodically back up the current account profile, e.g. storing the current account profile at 0 am every day. Then Step S 203  shown in  FIG. 2  is executed. That is, an account profile transmission request to the re-rating management apparatus  2   b  is sent, the request including the stored account profile. 
     It needs to be pointed out that there is no necessary sequence between Step S 202  and Step S 203 . Step S 202  is triggered by the online charging apparatus  2   a  upon receiving an online charging request while Step S 203  is triggered periodically. 
     The re-rating management apparatus  2   b , after receiving the rating information transmission request from the online charging apparatus  2   a , will extract the rated call detail record therefrom and store it locally. 
     The re-rating management apparatus  2   b , after receiving the account profile transmission request from the online charging apparatus  2   a , will extract the backed up account profile and store it locally. 
     The re-rating management apparatus  2   b  triggers the re-rating and determines the re-rating rule in accordance with external or internal conditions, i.e. executing Step S 204  shown in  FIG. 2 . The re-rating may be triggered externally, e.g. if the operator wants to charge the calls within a certain period of time in a new tariff, and alternatively it may be triggered internally, e.g. if the system finds that the charging within certain period of time has errors to be corrected and needs to be re-rated. Meanwhile, at Step S 204 , the re-rating management apparatus  2   b  will further determine a re-rating rule. For example, the current rating standard is 1 yuan/per minute and the new rating standard is 0.6 yuan/per minute. 
     Then, the re-rating management apparatus  2   b  will execute a re-calculating step, i.e. generating a rated call detail record in accordance with the re-rating rule, wherein the re-rated call detail record includes the call expense re-calculated for the call. 
     Specifically, one embodiment of the re-calculating step is as follows:
         a start point of re-rating is determined. For example, if the current date is February 15, and the operator wants to re-rate the calls from 0 am on February 2 to the current time in a new tariff, the re-rating management apparatus  2   b  will determine the start point of re-rating as 0 am on February 2, and then update the account profile at the start point of re-rating in accordance with the re-rating rule. For example, the rating rule for locally stored account profile at 0 am on February 2 is updated from 1 yuan/per minute to 0.6 yuan/per minute. Then a start point account profile transmission request is sent to the offline charging apparatus  2   c  including the updated account profile at the start point of re-rating.   the call detail record to be re-rated is determined in accordance with the re-rating rule. For example, if the current date is February 15, and the operator wants to re-rate all of the calls from February 2 to the current date in a new tariff, the re-rating management apparatus  2   b  will determine that the call detail records to be re-rated are all calls from February 2 to the current date. If the operator wants to re-rate the calls for a user A from February 2 to the current date in a new tariff, the re-rating management apparatus  2   b  will determine that the call detail records to be re-rated are the calls for the user A from February 2 to the current date.   as shown in Step S 206  of  FIG. 2 , a re-rating request message is sent to the offline charging apparatus  2   c , the message including one or more call detail records to be re-calculated. The re-rating management apparatus  2   b  may send to the offline charging apparatus  2   c  a re-rating request message including all call detail records to be re-rated. Alternatively, a re-rating request message for each call detail record to be re-rated may be sent respectively.       

     After receiving the start point account profile transmission request (as shown in Step S 205  of  FIG. 2 ), the offline charging apparatus  2   c  will extract the rating rule for re-rating therefrom. 
     After receiving the re-rating request message (as shown in Step S 206  of  FIG. 2 ), the offline charging apparatus  2   c  will extract one or more call detail records to be re-rated therefrom. 
     Then, the offline charging apparatus  2   c  re-rates the call detail records to be re-calculated in accordance with the rating rule for re-rating to generate re-rated call detail records. For example, the call detail records to be re-rated are shown in the following Table 1: 
     
       
         
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                   
                 Call Duration 
                   
               
               
                 . . . 
                 Caller 
                 Call Date 
                 Call Time 
                 (minute) 
                 . . . 
               
               
                   
               
             
             
               
                 . . . 
                 1381000000 
                 2011-2-3 
                 09:54 
                  9 
                 . . . 
               
               
                 . . . 
                 1381000009 
                 2011-2-2 
                 13:12 
                 12 
                 . . . 
               
               
                   
               
             
          
         
       
     
     Assuming that the current tariff for the system is 1 yuan/per minute and the tariff for re-rating is 0.6 yuan/per minute, the re-rated call detail records obtained by the offline charging apparatus  2   c  are shown in the following Table 2: 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Recalculated 
                   
               
               
                   
                   
                   
                 Call 
                 Call Duration 
                 Call Expense 
               
               
                 . . . 
                 Caller 
                 Call Date 
                 Time 
                 (minute) 
                 (yuan) 
                 . . . 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 . . . 
                 1381000000 
                 2011-2-3 
                 09:54 
                 9 
                 5.4 
                 . . . 
               
               
                 . . . 
                 1381000009 
                 2011-2-2 
                 13:12 
                 12 
                 7.2 
                 . . . 
               
               
                   
               
             
          
         
       
     
     After obtaining the re-rated call detail records, the offline charging apparatus  2   c  will execute Step S 207  shown in  FIG. 2 , i.e. sending a re-rating reply message to the re-rating management apparatus  2   b , the message including the one or more re-rated call detail records. Corresponding to the Step S 206 , the offline charging apparatus  2   c  may send a re-rating reply message including all re-rated call detail records or may alternatively send a re-rating reply message for each re-rated call detail record respectively. 
     After receiving the re-rating reply message, the re-rating management apparatus  2   b  updates a corresponding account profile in accordance with the re-rated call detail record included therein. In case of multiple re-rating reply messages, the re-rating management apparatus  2   b  will update corresponding account profile after receiving all re-rated call detail records. For example, if the system needs to re-rate the calls from 0 am on February 2 to the current time on February 15, the re-rating management apparatus  2   b  reads the account balance in the account profile at 0 am on February 2 and then reads the records of February 2 in the re-rated call detail records, calculates the account balance at 0 am on February 3, and updates the account profile at 0 am on February 3. It will be understood that the rating rule for the account profile on February 3 will also be updated. On the analogy of this, the re-rating management apparatus  2   b  calculates respective account balances from February 3 to the current date and updates corresponding account profile. 
     Then, the re-rating management apparatus  2   b  will send to the online charging apparatus  2   a  an account profile update request, as shown in Step S 208  of  FIG. 2 , the account profile update request including the updated account profile such as the updated account profile from February 2 to the current date. 
     After receiving the account profile update request, the online charging apparatus  2   a  updates the locally stored account profile in accordance with the account profile included therein, e.g. updating the locally stored account profiles from February 2 to the current date to the corresponding account profiles in the account profile update request. 
     Now, the charging system of the present invention finishes the re-rating process for prepaid users, achieves re-rating of the call detail records, and timely updates the corresponding account profile without affecting the real-time use by users. 
       FIG. 3  illustrates a structural block diagram of the online charging apparatus  2   a  according to a specific embodiment of the present invention. In  FIG. 3 , the online charging apparatus  2   a  includes a rating means  301 , a rating information transmitting means  302 , an account backing up means  303  and a first account updating means  304 . 
     In the following, the operating process of the online charging apparatus  2   a  will be described in more detail with reference to  FIG. 2 . 
     Firstly, the rating means  301  receives the online charging request from Network  201 , as shown in Step S 201  of  FIG. 2 , and the online charging request includes detailed information of the call to be rated. For this request, the rating means  301  will execute the following actions: rating the call detail records included in the online charging request to generate rated call detail records. For example, the expense for a call may be obtained in accordance with the current rating rule and the call duration included in the call detail record, and then the account profile of a user is updated in accordance with the expense caused by the call and the current balance of the call expense for the account corresponding to the call. 
     Thereafter, the rating information transmitting means  302  sends the rating information transmission request to the re-rating management means  2   b , as shown in Step S 202  of  FIG. 2 , wherein the rating information transmission request includes the generated rated call detail record. 
     In addition, the account backing up means  303  will periodically back up the current account profile, e.g. storing the current account profile at 0 am every day, and then executes Step S 203  shown in  FIG. 2 , i.e. sending an account information transmission request to the re-rating management means  2   b , the request including the stored account profile. 
     It needs to be pointed out that there is no necessary sequence between Step S 202  performed by the rating information transmitting means  302  and Step S 203  performed by the account backing up means  303 . Step S 202  is triggered by the rating means  301  upon receiving the online charging request while Step S 203  is triggered periodically. 
     The first account updating means  304  is adapted to receive the account profile update request from the re-rating management apparatus  2   b , as shown in Step S 208  of  FIG. 2 . The account profile update request includes the re-calculated account profile, and the first account updating means  304  updates the locally backed up account profile in accordance with the updated account profile. For example, if the account profile update request includes the updated account profile from February 2 to the current date, the first account updating means  304  will update the locally stored account profile from February 2 to the current date to the account profile in the account profile update request. 
       FIG. 4  illustrates a structural block diagram of the re-rating management apparatus  2   b  according to a specific embodiment of the present invention. In  FIG. 4 , the re-rating management apparatus  2   b  includes a rating information receiving means  401 , an account profile receiving means  402 , a triggering means  403 , a re-calculating means  404  and a second account updating means  405 . 
     In the following, the operating process of the re-rating management apparatus  2   b  will be described in more detail with reference to  FIG. 2 . 
     The rating information receiving means  401  receives the rating information transmission request from the online charging apparatus  2   a , as shown in Step S 202  of  FIG. 2 , and then it will extract and locally store the rated call detail records. 
     The account profile receiving means  402  receives the account profile transmission request from the online charging apparatus  2   a , as shown in Step S 203  of  FIG. 2 , and then it will extract and locally store the backed up account profile. 
     The triggering means  403  triggers re-rating and determines a re-rating rule in accordance with external or internal conditions, i.e. executing Step S 204  shown in  FIG. 2 . The re-rating may be triggered externally, e.g. if the operator wants to charge the calls within a certain period of time in a new tariff, and it may alternatively be triggered internally, e.g. if the system finds that the charging within certain period of time has errors to be corrected and needs to be re-rated. Meanwhile, at Step S 204 , the triggering means  403  will further determine the re-rating rule. For example, the current rating standard is 1 yuan/per minute and the new rating standard is 0.6 yuan/per minute. 
     Then, the re-calculating means  404  will execute the re-calculating step, i.e. generating the re-rated call detail record in accordance with the re-calculating rule, wherein the re-rated call detail record includes the re-calculated call expense for a call. 
     Preferably, the re-calculating means  404  further includes a start point account updating means  404   a , a determining means  404   b , a re-rating request sending means  404   c  and a re-rating reply receiving means  404   d.    
     The start point account updating means  404   a  is configured to determine a start point of re-rating, e.g. if the current date is February 15, and the operator wants to re-rate the calls from 0 am on February 2 to the current time in a new tariff, the re-rating management apparatus  2   b  will determine the start point of re-rating as 0 am on February 2. Then the start point account updating means  404   a  updates the account profile of the start point of re-rating in accordance with the re-rating rule, e.g. updating the rating rule for locally stored account profile at 0 am on February 2 from 1 yuan/per minute to 0.6 yuan/per minute. Then the start point account updating means  404   a  sends to the offline charging apparatus  2   c  a start point account profile transmission request including the updated account profile at the start point of re-rating. 
     The determining means  404   b  determines the call detail record to be re-rated in accordance with the re-rating rule, e.g. if the current date is February 15, and the operator wants to re-rate all of the calls from February 2 to the current date in a new tariff, the determining means  404   b  will determine that the call detail records to be re-rated are all calls from February 2 to the current date. If the operator wants to re-rate the calls for a user A from February 2 to the current date in a new tariff, the determining means  404   b  will determine that the call detail records to be re-rated are the calls for the user A from February 2 to the current date. 
     The re-rating request sending means  404   c  sends a re-rating request message to the offline charging apparatus  2   c , as shown in Step S 206  of  FIG. 2 , the message including one or more call detail records to be re-calculated. The re-rating request sending means  404   c  may send to the offline charging apparatus  2   c  a re-rating request message including all call detail records to be re-rated, and it may alternatively send a re-rating request message for each call detail record to be re-rated respectively. 
     The re-rating reply receiving means  404   d  is configured to receive a re-rating reply message from the offline charging apparatus  2   c , as shown in Step S 207  of  FIG. 2 , and the re-rating reply message includes one or more re-rated call detail records re-calculated by the offline charging apparatus  2   c.    
     After the re-rating reply receiving means  404   d  receives the re-rating reply message, the second account updating means  405  updates a corresponding account profile in accordance with the re-rated call detail record included therein. In case of multiple re-rating reply messages, the second account updating means  405  will update corresponding account profile after receiving all re-rated call detail records. For example, if the system needs to re-rate the calls from February 2 to February 15, the second account updating means  405  reads the account balance in the account profile at 0 am on February 2 and then reads the records of February 2 in the re-rated call detail records, calculates the account balance at 0 am on February 3, and updates the account profile at 0 am on February 3. It will be understood that the rating rule for the account profile on February 3 will also be updated. On the analogy of this, the second account updating means  405  calculates respective account balances from February 3 to the current date and updates corresponding account profile. 
     Then, the second account updating means  405  will send to the online charging apparatus  2   a  the account profile update request, as shown in Step S 208  of  FIG. 2 , the account profile update request including the updated account profile such as the updated account profile from February 2 to the current date. 
       FIG. 5  illustrates a structural block diagram of the offline charging apparatus  2   c  according to a specific embodiment of the present invention. In  FIG. 5 , the offline charging apparatus  2   c  includes a start point account profile receiving means  501 , a re-rating request receiving means  502 , a re-rated record generating means  503  and a re-rating reply sending means  504 . 
     In the following, the operating process of the offline charging apparatus  2   c  will be described in more detail with reference to  FIG. 2 . 
     The start point account profile receiving means  501  receives the start point account profile transmission request from the re-rating management apparatus  2   b , as shown in Step S 205  of  FIG. 2 , the request including the updated account profile at the start point of re-rating. The start point account profile receiving means  501  will extract the rating rule for the re-rating therefrom. 
     The re-rating request receiving means  502  receives the re-rating request message from the re-rating management apparatus  2   b , as shown in Step S 206  of  FIG. 2 , and then extracts one or more call detail records to be re-rated therefrom. 
     Then, the re-rated record generating means  503  re-rates the call detail records to be re-calculated in accordance with the rating rule for re-rating to generate re-rated call detail records. For example, the call detail records to be re-rated are as shown in the above Table 1. If the current tariff of the system is 1 yuan/per minute while the tariff of re-rating is 0.6 yuan/per minute, the re-rated call detail records obtained by the offline charging apparatus  2   c  are as shown in the above Table 2. 
     After the re-rated record generating means  503  has generated the re-rated call detail record, the re-rating reply sending means  504  will execute Step S 207  as shown in  FIG. 2 , i.e. sending to the re-rating management apparatus  2   b  a re-rating reply message including one or more re-rated call detail records. The re-rating reply sending means  504  may send a re-rating reply message including all re-rated call detail records and may alternatively send a re-rating reply message for each re-rated call detail record respectively. 
     As described above, the online charging apparatus  2   a , the re-rating management apparatus  2   b  and the offline charging apparatus  2   c  are all functional entities, and they should not necessarily be understood by those skilled in the art to be physical network entities. 
     For those skilled in the art, the present invention is obviously not limited to the details of the illustrative embodiments, and it can be carried out in other specific forms without departure from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments shall be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above explanations, and thus the present invention intends to include all variants within the meaning and scope of equivalent elements of the claims. In addition, the word “include” obviously does not exclude other units or steps, and the singular form does not exclude the plural form. The wordings of first, second, etc. are used to represent names rather than any specific sequence.