METHOD OF LIMITING CALL CHARGES IN A RADIO TELECOMMUNICATIONS NETWORK
BACKGROUND OF THE INVENTION
Technical Field of the Invention
This invention relates to radio telecommunication systems and, more particularly, to a method of limiting the amount of charges that can be incurred on a cellular subscriber's account. Description of Related Art
Many systems have been proposed to control fraud in cellular telecommunication systems. Some have been successful in reducing the number of fraudulent calls under certain circumstances. However, none have been totally successful, and millions of dollars of fraudulent calls still occur each year. It would be advantageous to have a method of limiting the charges which a fraudulent user can make to a legitimate subscriber's account.
An additional problem faced by cellular subscribers is the control of their own charges for cellular calls. Many subscribers do not realize the amount of charges they are incurring until it is too late, and they receive a very large bill at the end of the month. It would be advantageous to have a method of setting a spending limit for a subscriber, and notifying the subscriber when that spending limit has been reached.
Although there are no known prior art teachings of a solution to the aforementioned deficiency and shortcoming such as that disclosed herein, U.S. Patent Number 5,450,477 to Amarant et al. (Amarant) and European Patent Application EPO 629 072 Al to Telia AB (Telia) discuss subject matter that bears some relation to matters discussed herein. Amarant discloses a method of monitoring the connect time of a call in regards to an assigned limit to an account. When a credit card or debit card is utilized to initiate a call, the card is validated and the available balance in the account is determined. Based upon the available balance in the account, a time limit for the call is established. If the call exceeds the time limit, the system operator terminates the call. When a call terminates, the billing information is sent
to a network database that subtracts the charges from the balance of the account.
Amarant primarily teaches an algorithm to calculate the debit.
Amarant, however, describes a method that is suitable for a landline telephone system. Amarant does not teach or suggest a method of establishing a debit limit in a cellular telecommunication system, communicating the necessary information between nodes in the cellular system, and disconnecting calls that exceed the established debit limit.
Telia discloses an arrangement in a telephone system for controlling debiting of services. Telia briefly describes a system that is suitable for a landline telephone system, but does not provide any details about how such a system would be implemented. In addition, Telia does not teach or suggest a method of establishing a debit limit in a cellular telecommunication system, communicating the necessary information between nodes in the cellular system, and disconnecting calls that exceed the established debit limit. Review of each of the foregoing references reveals no disclosure or suggestion of a system or method such as that described and claimed herein.
In order to overcome the disadvantage of existing solutions, it would be advantageous to have a method of limiting the charges on a cellular subscriber's account to a preset limit. Such a method would limit fraud if a fraudulent user attempts to make calls that are too lengthy or too expensive. In addition, the method would enable cellular subscribers to set their own spending limits and, for example, to end a call when the toll reaches the subscriber's limit. The present invention provides such a method.
SUMMARY OF THE INVENTION
In one aspect, the present invention is a method of controlling fraud if a fraudulent user attempts to utilize a legitimate subscriber's mobile station to make calls that are too lengthy or too expensive. In addition, the present invention enables cellular subscribers to set their own spending limits and, for example, to end a call when the toll reaches the subscriber's limit.
Thus, in one aspect, the present invention is a method in a radio telecommunication system of limiting charges on a subscriber's account to an available balance. The method begins by storing the available balance in the subscriber's home location register (HLR) and storing, in a subscriber profile in the subscriber's HLR, an instruction to monitor charges incurred by the subscriber's mobile station. This is followed by informing the HLR that the subscriber has originated a call. The HLR determines the parameters of the call and converts the available balance to a time limit for the call. This is followed by instructing an Originating Mobile Switching Center (O-MSC) to time the call, and disconnecting the call if the call exceeds the time limit.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and its numerous objects and advantages will become more apparent to those skilled in the art by reference to the following drawing, in conjunction with the accompanying specification, in which:
FIG. 1 is a message signaling diagram illustrating the flow of messages between affected nodes of a radio telecommunications network when the present invention is implemented for calls terminating at a mobile station operating in the network; FIG. 2 is a message signaling diagram illustrating the flow of messages between affected nodes of a radio telecommunications network when the present invention is implemented for calls originating at a mobile station operating in the network; and
FIGS. 3A and 3B are a flow chart illustrating the steps of the method of the present invention when the present invention is implemented for calls originating at a mobile station operating in the network.
DETAILED DESCRIPTION OF EMBODIMENTS
The present invention defines the signaling interface between nodes in a radio telecommunications network required to implement a method of limiting the charges on a subscriber's account to a preset limit. The method of the present invention
limits fraud if a fraudulent user attempts to make calls that are too lengthy or too expensive. In addition, the method enables subscribers to set their own spending limits and, for example, to end a call when the toll reaches the subscriber's limit.
In the present invention, the operator or the subscriber may request that call charges or call lengths from the subscriber's mobile station be monitored. This information is stored in the subscriber profile (subscriber category) in the subscriber's home location register (HLR). A subscriber may request the monitoring service to ensure that he does not exceed a predetermined debit limit.
The operator may request the monitoring service whenever fraudulent usage is suspected. Any call originated from a subscriber's mobile station may be a fraudulent call. When the dialed digits reach the HLR, an analysis of the dialed digits indicates whether the call is a local call or a long distance call. If it is a long distance call, it is more likely that the call is a target of fraud. Therefore, the method of the present invention may include a step that activates call monitoring only if the dialed digits analysis indicates that the call is a long distance call.
A timer in the Gateway Mobile Switching Center (G-MSC) determines whether the call exceeds a predetermined length which is calculated based on the available balance in the subscriber's account. If so, the call is disconnected. The system may optionally play an announcement notifying the subscriber of the reason that the call was disconnected. The length of the call may be varied, depending on the applicable charge rate. For example, domestic long distance calls may be limited to 30 minutes while international long distance calls may be limited to 10 minutes.
FIG. 1 is a message signaling diagram illustrating the flow of messages between affected nodes of a radio telecommunications network when the present invention is implemented for calls terminating at a mobile station operating in the network. A call 11 for the mobile station is first received in a Gateway Mobile Switching Center (G-MSC) 12. The G-MSC sends a Location Request (LOCREQ) Invoke message 13 to the subscriber's Home Location Register (HLR) 14. The HLR sends a Routing Request (ROUTEREQ) Invoke message 15 to the Visited
Location Register/Mobile Switching Center (V-MSC) 16 where the mobile station
is operating. In systems which support paging-befo re- routing, the V-MSC then pages the mobile station and receives a page response.
Whether paged or not, the V-MSC then sends a Routing Request (routereq) Return Result message 17 to the HLR 14. The HLR checks the subscriber profile to determine whether the operator or the subscriber has requested that call charges or call lengths from the subscriber's mobile station be monitored. If call monitoring is activated, the HLR includes a new parameter (timer) in the Location Request (locreq) Return Result message 18 commanding the G-MSC to monitor the length of the call, and informing the G-MSC of the allowable length of the call. The operator or the subscriber may enter a debit limit, and the HLR calculates the allowable length of the call. The method illustrated in U.S. Patent No. 5,450,477 to Amarant et al. , which is hereby incorporated by reference, may be utilized as a suitable method of converting a debit limit to time and vice versa. The call is then set up at 19 and monitored by the G-MSC 12. If the time period expires before the end of the call, the G-MSC 12 sends a
Notification Invoke message 21 to the HLR 14 indicating that the timer has expired. The HLR sends a notification Return Result message 22 to the G-MSC ordering the G-MSC to disconnect the call. The Notification Invoke message 21 and the notification Return Result message 22 are new IS-41 messages. Thereafter, an announcement may be played to the mobile subscriber with the reason for the disconnection. This announcement is currently played by the G-MSC 12, and the call is then disconnected.
FIG. 2 is a message signaling diagram illustrating the flow of messages between affected nodes of a radio telecommunications network when the present invention is implemented for calls originating at a mobile station operating in the network. When a subscriber operating a mobile station in an originating MSC (O- MSC) 31 originates a call, an Origination Request (ORIGREQ) Invoke message 32 is sent to the subscriber's HLR 33. The HLR checks the subscriber profile to determine whether the operator or the subscriber has requested that call charges or call lengths from the subscriber's mobile station be monitored. If call monitoring is activated, the HLR includes a new parameter (timer) in the Origination Request
(origreq) Return Result message 34 commanding the O-MSC 31 to monitor the length of the call, and informing the O-MSC of the allowable call length. The operator or the subscriber may enter a debit limit, and the HLR calculates the allowable length of the call. The call is then set up at 35 and monitored by the O- MSC 31. The call may be to another mobile station operating within the Public
Land Mobile Network (PLMN) or the Public Switched Telephone Network (PSTN) 36.
If the time period expires before the end of the call, the O-MSC 31 sends a Notification Invoke message 37 to the HLR 33 indicating that the timer has expired. The HLR sends a notification Return Result message 38 to the O-MSC ordering the
O-MSC to disconnect the call. The Notification Invoke message 37 and the notification Return Result message 38 are new IS-41 messages. Thereafter, an announcement may be played to the mobile subscriber with the reason for the disconnection. This announcement is currently played by the O-MSC 31, and the call is then disconnected.
FIG. 3 is a flow chart illustrating the steps of the method of the present invention when the present invention is implemented for calls originating at a mobile station operating in the network. The process begins at step 41 where it is determined whether the subscriber desires to set a debit limit for his account. If not, the process ends at 42. If the subscriber desires to set a debit limit, the process moves to step 43 where the subscriber requests that call charges from his mobile station be monitored. The subscriber also enters the allowable debit limit.
The process may also begin at step 44 where it is determined whether fraudulent usage of the subscriber's mobile station is suspected. If not, the process ends at 45. If fraudulent usage is suspected, the process moves to step 43 where the system operator requests that call charges from the subscriber's mobile station be monitored. The operator also enters an allowable debit limit.
At step 46, the subscriber's HLR stores an instruction for call monitoring in the subscriber's profile (category). The instruction includes the allowable debit limit. At step 47, the subscriber originates a call. The operator may desire to implement the present invention only for long distance calls, which are more likely
to be fraudulent. Therefore, at this point, the process may optionally determine whether the call is a long distance call. This may be accomplished in the HLR through an analysis of the dialed digits. If the call is not a long distance call, the process ends at 49. If the call is determined to be a long distance call (or if optional step 48 is not implemented), the process moves to step 51 where the HLR checks the subscriber profile for the call monitoring instruction and allowable debit limit. At step 52, the HLR determines a charge rate for the call and converts the available balance in the subscriber's account to a time limit for the call. The charge rate may be determined from the time of day, the day of the week, the origin and the destination for the call, and applicable charge rate tables. The time limit for the call may be calculated by dividing the available balance by the charge rate. The process then moves to FIG. 3B.
The process continues at step 53 where the HLR provides the time limit to the originating MSC (O-MSC), and instructs the O-MSC to time the call. At step
54, the O-MSC times the call, and at 55, it is determined, while the call is in progress, whether the call is exceeding the time limit. If not, and the call ends before the time limit is exceeded, the process moves to step 56 where the O-MSC informs the HLR of the time utilized for the call. The HLR converts the time utilized to a debit charge at 57, and updates the available balance in the subscriber profile at 58. The process then returns to step 47 and waits for the subscriber to originate another call.
If, however, the call exceeds the time limit at step 55, the process moves to step 61 where the O-MSC informs the HLR that the time limit has expired. The HLR instructs the O-MSC to disconnect the call at 62. At step 63, the O-MSC disconnects the call. An announcement may be played to the subscriber at 64 notifying him of the reason for the disconnection.
It is thus believed that the operation and construction of the present invention will be apparent from the foregoing description. While the method, apparatus and system shown and described has been characterized as being preferred, it will be readily apparent that various changes and modifications could be made therein
without departing from the spirit and scope of the invention as defined in the following claims.