Invention relates to prevention of termination of calls made by the subscribers who use prepaid lines in mobile communication networks due to insufficient funds and to completion of the cali. PRIOR ART

Two basic pricing systems as postpaid and prepaid are used in mobile communication sector In prepaid lines, user of the line can make use of communication services in accordance with the current funds.

In the current situation, a call which is started from a prepaid line is automatically terminated if the funds are used up during the call. In this case, as the party which receives the cali does not know why the call ended, it may be thought that an error regarding the mobile network, being out of the coverage area or a problem with the mobile device has occurred. The calling party, however, cannot make a call before topping up funds. Although there are reverse charge call services provided for the subscribers with insufficient funds to allow them making calls, in order to make a call, they have to dial a service number and restart the calling process. Apart from being unpractical, this method causes dissatisfaction among the caller party and the called party due to the interruption of the call for such a reason.

Korean patent application No. KR101000103B1 relates to automatically initiating a reverse charge call in prepaid Sines. The anticipated method involves checking the funds when a user with prepaid line wants to start a call and starting a reverse charge call in case the funds at e insufficient for making a call. As can be understood, said application is capable of starting a reverse charge call only if the funds are insufficient at the start of a call. It does not have a function for sustaining the call in case the funds are used up during the call. Thus, said application cannot provide solution for the problems mentioned above.

The European Patent Application No. EP1777932 (A1 ) relates to a method that provides continuing the call by initiating an automatic reverse charge call when the funds of the caller party are used up. The parties may continue the call in this case. However, this situation occurs without the request and approval of the subscribers. Directly initiating a reverse charge call without giving the caller party or the called party any option is not always desired. As a result, due to the problems mentioned above, it is required to make a development in the related technical field. BRIEF DESCRIPTION OF THE INVENTION

The invention relates to call completion method in prepaid lines developed in order to eliminate the abovementioned disadvantages and to present new advantages to the related technical field.

The main object of the invention is to prevent termination of calls made by the subscribers who use prepaid lines in mobile communication networks due to insufficient funds and to provide sustainment of the call. Another object of the invention is to provide sustainment of the call in case the funds of the caller party are used up during said call by presenting the caller party the options of topping up funds or initiating reverse charge call.

Another object of the invention is to provide sustainment of the call in case the funds of the caller party are used up during said call by presenting the called party the options of transferring funds or calling back.

In order to achieve all the objects mentioned above and to be understood from the detailed description below, the present invention relates to a call completion system which comprises a mobile switching center that directs the call of the caller party to the called party in a mobile communication network where the caller party owns a prepaid line; a service control unit to which the calls received to said mobile switching center are directed and which checks the funds of the caller party periodically before and during the call; and an accounting service which keeps the funds information of the prepaid line owners. Said call identification system comprises a call completion control unit

- which provides direction of the call to mobile switching center by the service control point,

- which notifies the called and/or caller party that the call will be terminated due to insufficient funds and which vocally announces the call completion services that may be provided by the mobile operator for the sustainment of the call,

- which, in accordance with the selection of the subscriber, terminates the call or directs the call to selected call completion service in case the funds of the caller are used up during the call.

In a preferred embodiment of the invention, topping up funds of the caller party and/or reverse charge call services are provided within the scope of call completion services. By this way, the caller party can initiate a reverse charge call without any process and without memorizing a long/short service number or top up the funds after the call is terminated.

In another preferred embodiment of the invention, the called party is provided the share funds and call back services within the scope of call completion service. By this way, the called party can call back the caller party without dialing or transfer funds to the caller and assist the caller to call again. Alongside the call completion services, as the called party is notified that the call will be terminated due to insufficient funds, called party will know the reason for the termination of the call. Mobile operators ensure customer satisfaction thanks to call completion services. In addition to this, thanks to the use of services such as topping up funds, making reverse charge calls and fund sharing, additional profit and increase in the call traffic are achieved.

The present invention should be evaluated with the figures described below to ensure the best understanding of the embodiment and advantages together with the additional elements of the invention.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is the schematic view of the elements that form the call completion system in prepaid lines.

REFERENCE NUMBERS 10 Call Completion System

1 Base Station (BTS)

2 Base Station Controller (BSC)

3 Base Station (BTS)

4 Base Station Controller (BSC)

5 Mobile Switching Center (MSC)

6 Service Control Unit (SCP)

7 Pricing System 8 Ca!i Completion Control Unit

9 Call Completion Services

9.1 Funds Top Up Service

9.2 Reverse Charge Call Service

9.3 Call Back Service

9.4 Funds Sharing Service

A: Caller Subscriber

B: Called Subscriber

DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, the novelty according to the present invention is described only for the subject to be understood better without any iimiting effect. Accordingly, in the statement beiow, a call completion system (10) and a call identification method which provides completion of the calls which are terminated due to insufficient funds in prepaid lines via said system (10) the representative illustration of which are given in Figure 1 are given.

Figure 1 is the schematic view of the call completion system (10). When the owner of a prepaid line starts a call, the call request reaches to a mobile switching center (5) via a base station (1 ) and a base station controller (2). Said mobile switching center (5) detects that the call request is received from a prepaid line and transfers the call to a service control unit (6) Said service control unit (6) queries whether the subscriber has enough funds to initiate a cai! or not The query process is conducted over a pricing system (7) which keeps the funds information of the prepaid line owners and conducts the pricing process. If the caller (A) has sufficient funds, the call is transferred to the called subscriber (B) via the mobile switching center (5) over the base station (3) and the base station controller (4) that provides service to the subscriber. So the call between the parties is initiated. During the call, service control unit (6) queries the funds of the caller (A) periodically by making contact with the pricing system (7). The call is sustained if at least the funds for continuing the call until the next query period exists, in the case that the funds are insufficient, a request is sent from the service control unit (6) to the mobile switching center (5) for diverting the caii. A call identification control unit (8) is given as the address to which the call will be diverted. Said call identification control unit (8) notifies the caller and/or the called subscribers (A _; B) with an audible announcement over the IVR menu. Within the scope of the audible announcement notified to the caller (A), it is stated that the funds are used up and the call will be terminated. Moreover, caller (A) is asked whether s/he wants to use one of the funds top up or reverse charge call services. Caller (A) makes the decision by dialing over the mobile device. The selection reaches to the call completion control unit (8) with a DTMF signal. In accordance with the selection of the caller (A) the call Is terminated or directed to the call completion service (9). If the caller (A) wants to top up funds, s/he is directed to funds top up service (9.1), if s/he wants to make a reverse charge call, s/he is directed to reverse charge call service (9.2). In alternative embodiments of the invention, it is possible to provide the subscribers with various services related to sustaining the call.

In the audible announcement notified to the called party (B), the information regarding the use up of the funds of the caller (A) and the termination of the call are stated. Moreover, it will be asked whether s/he wants to use any one of the share funds or call back services. The called party (B) makes the decision by dialing over the mobile device. The selection reaches to the call completion control unit (8) with a DTMF signal. In accordance with the selection of the called party (A) the call is terminated or directed to the calf completion service (9). If the called party (A) wants to share funds, s/he is directed to share funds service (9.3), if s/he wants to call back, s/he is directed to call back service (9.4). In alternative embodiments of the invention, it is possible to provide the subscribers with various services related to sustaining the call other than stated call completion services

In line with the information given above, the call completion method according to the invention comprises following process steps:

- Another line is called from a prepaid line.

- The call is directed to the mobile switching center (5) via the base station ( 1 ) and the base station controller (2),

- Mobile switching center (5) detects that the caller line is prepaid and directs the call to service control unit (6),

- Service control unit (6) asks the funds of the subscriber to the pricing system (7) and initiates the call if there are sufficient funds,

- Via the mobile switching center (5), the call is directed to the called subscriber (A) over the base station (3) and the base station controller (4) which serve to the called subscriber (B),

As a result of the stated process steps, the call between the caller and the called parties is initiated. After this phase, the process steps below are executed within the scope of the call completion method: - Service control unit (8) queries the funds of the caller (A) periodically,

- if it is detected that the funds are insufficient for the call to continue, a request is sent to the mobile switching center (5) for the call to be directed to the call completion control unit (8),

- Call completion control unit (8) notifies the caller subscriber (A) or the called subscriber (B) about the call completion services (9) that can be provided to them by the mobile operator via audible announcement,

- In accordance with the selection of the subscriber (A,B), the call is terminated or the subscriber (A,B) is directed to related call completion services (9).