Abstract:
A mobile terminal and method for transferring call charges between mobile terminals are disclosed. To transfer call-related charges between mobile terminals, the mobile terminal and call charge transfer method place a call by a calling mobile terminal to a called mobile terminal to establish a call connection for conversation, transmit a call transfer request by the calling mobile terminal to impose call-related charges on the called mobile terminal, and perform, if the called mobile terminal accepts the call transfer request, a call transfer operation to impose the call-related charges on the called mobile terminal, and maintain, if the called mobile terminal rejects the call transfer request, the call to impose the call-related charges on the calling mobile terminal. As a result, during a call between mobile terminals, the called user can accept a call transfer request of the calling user to transfer call-related charges to the called party, thereby enabling flexible and efficient billing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application Serial No. 2006-0013465 filed in the Korean Intellectual Property Office on Feb. 13, 2006, the entire disclosure of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a mobile terminal and method for transferring call charges. More particularly, the present invention relates to a mobile terminal and method of transferring call charges between mobile terminals wherein a charge associated with a call between mobile terminals can be transferred to a party having an advantageous fee charging structure to reduce user expenses. 
     2. Description of the Related Art 
     A mobile terminal is a wireless communication device that can be readily carried and moved by a person for communication at most times and places. Such a mobile terminal as a mobile station (MS) can be freely moved in service areas formed by base stations (BS) of a mobile network system to which the mobile terminal is subscribed, and used to make a wireless connection to a desired recipient through a communication path established by monitoring, controlling and switching operations of a mobile switching center (MSC). 
     In recent years, mobile terminals have become popularized and are currently carried by numerous users. 
     A user carrying a mobile terminal may place/receive a call to/from another user. Sometimes, during an ongoing call, it may be difficult for a user to identify which of the parties placed the call and which received the call. An ordinary mobile terminal displays, as information about the other party, a registered name and phone number if the other party is registered in a phone number list, or only a phone number if the other party is not registered, and does not display calling/called party information. Hence, it may be difficult for the user to identify which of the parties is the calling party and which is the called party prior to termination of the current call. 
     A user may be inconvenienced if they are unable to use their mobile terminal owing to discharge of the battery or loss of the mobile terminal itself. The user may be more inconvenienced if public or wired phones are not immediately available. 
     In such situations, the user may try to use another person&#39;s mobile terminal. However, because of a call charge, the other person may be reluctant to allow the user to use their mobile terminal, and therefore the user may encounter difficulty in using another person&#39;s mobile terminal. 
     To solve this call charge problem in the use of another person&#39;s mobile terminal, Korean Patent Publication No. 2004-0017464 discloses a call charge method wherein, in the case of a call made by use of another person&#39;s mobile terminal, an associated call charge is imposed on a mobile phone number designated by the user. However, this call charge method requires a complex authentication procedure including password input, thereby lengthening the time in use of another person&#39;s mobile terminal. 
     Korean Patent Publication No. 2005-0104776 discloses another call charge method wherein if a call is placed by a person registered in an allotment list stored in a mobile terminal, the call is treated as a collect call. This call charge method enables the called party to be appointed in advance to pay the call charge. However, the method does not permit change of the paying party during an ongoing call, thereby imposing an entire charge associated with the call on the called party. 
     Accordingly, there is a need for an improved mobile terminal and method for transferring call charges between mobile terminals. 
     SUMMARY OF THE INVENTION 
     Exemplary embodiments of the present invention address at least the above problems and/or disadvantages and provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a method of displaying calling/called party information on a mobile terminal. 
     Another object of the present invention is to provide a method of call charge transfer between mobile terminals. 
     In accordance with an exemplary embodiment of the present invention, there is provided a mobile terminal and method for transferring a call charge between mobile terminals, comprising placing a call by a calling mobile terminal to a called mobile terminal to establish a call connection for conversation, transmitting a call transfer request by the calling mobile terminal to impose call-related charges on the called mobile terminal, and performing, if the called mobile terminal accepts the call transfer request, a call transfer operation to impose the call-related charges on the called mobile terminal, and maintaining, if the called mobile terminal rejects the call transfer request, the call to impose the call-related charges on the calling mobile terminal. 
     In accordance with another exemplary embodiment of the present invention, there is provided a mobile terminal and method for transferring a call charge between mobile terminals, comprising placing a call by a calling mobile terminal to a called mobile terminal to establish a call connection for conversation, transmitting a call charge transfer request by the calling mobile terminal to impose call-related charges on the called mobile terminal, and setting, if the call charge transfer request is accepted, paying party data of a billing server in a mobile switching center to the called mobile terminal, and maintaining, if the call charge transfer request is rejected, the paying party data of the billing server in the mobile switching center. 
     In an exemplary embodiment of the present invention, during a call between mobile terminals, the called user may accept a call transfer request of the calling user to transfer call-related charges to the called party, thereby enabling flexible and efficient billing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram showing the configuration of a mobile terminal related to an exemplary embodiment of the present invention; 
         FIG. 2  is a schematic diagram showing the configuration of a call charge transfer apparatus according to an exemplary embodiment of the present invention; 
         FIG. 3  is a flow chart illustrating a method of call charge transfer between mobile terminals according to an exemplary embodiment of the present invention; 
         FIGS. 4A to 4B  are flow diagrams illustrating a method of call transfer between mobile terminals according to another exemplary embodiment of the present invention; and 
         FIGS. 5A to 5K  are screen representations illustrating a procedure of call transfer between mobile terminals according to an exemplary embodiment of the present invention. 
     
    
    
     Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the embodiments of the invention and are merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
     As shown in  FIG. 1 , the exemplary mobile terminal comprises a wireless communication module  110 , a data processor  120 , an audio processor  130 , a memory unit  140 , a display unit  150 , a key input unit  160 , and a control unit  170 . 
     The wireless communication module  110  performs data transmission and reception operations for the mobile terminal. The wireless communication module  110  includes a radio frequency (RF) transmitter for up-converting the frequency of a signal to be transmitted and amplifying the signal, and an RF receiver for low-noise amplifying a received signal and down-converting the frequency of the signal. The wireless communication module  110  establishes channels for voice and data communication with external communication devices, and transmits/receives short messages to/from external communication devices. In an exemplary embodiment, during an ongoing call between calling and called mobile terminals, the calling mobile terminal transmits a ‘call transfer request’ signal to the called mobile terminal when a ‘call transfer’ menu item is selected by the calling user, and the called mobile terminal transmits a ‘call transfer accept’ signal to the calling mobile terminal according to a selection of the called user. 
     The data processor  120  includes a transmission module for encoding and modulating a signal to be transmitted through a wireless channel, and a reception module for demodulating and decoding a signal received through a wireless channel. 
     The audio processor  130  may include a coder/decoder (codec). The codec includes a data codec for processing packet data, and an audio codec for processing an audio signal such as a voice signal. The audio processor  130  converts a digital audio signal from the data processor  120  into an analog signal through the audio codec to reproduce the analog signal through a speaker SPK. The audio processor  130  also converts an analog audio signal from a microphone MIC into a digital audio signal through the audio codec to output the digital audio signal to the data processor  120 . 
     The memory unit  140  stores programs for controlling general operations of the mobile terminal, and data resulting from execution of the programs. 
     The display unit  150  displays input display data on a screen  150 A under the control of the control unit  170 . In an exemplary embodiment of the present embodiment, the display unit  150  may also display a ‘call transfer’ menu item under the control of the control unit  170  during a call, and display call transfer steps if the user selects the ‘call transfer’ menu item. 
     The key input unit  160  includes a plurality of keys for inputting numerals and characters, and a plurality of control keys for controlling operations of the mobile terminal. In an exemplary embodiment of the present embodiment, a ‘call transfer’ menu item may be selectable during a call by the user through the key input unit  160 . 
     The control unit  170  controls the overall operation of the mobile terminal. The control unit  170  also controls data transmission and reception. In an exemplary embodiment of the present embodiment, the control unit  170  displays calling/called party information from the wireless communication module  110  through the display unit  150 . 
     During a call between calling and called mobile terminals, a control unit  170  of the calling mobile terminal transmits a ‘call transfer request’ signal through a wireless communication module  110  thereof to the called mobile terminal when a ‘call transfer’ menu item is selected by the calling user. In reply, upon reception of the ‘call transfer request’ signal, a control unit  170  of the called mobile terminal transmits a ‘call transfer accept’ signal through a wireless communication module  110  thereof to the calling mobile terminal according to a selection of the called user. 
     After completion of the call transfer, each control unit  170  preferably displays calling/called party information corresponding to the transferred call through the display unit  150  to inform the user. 
       FIG. 2  is a block diagram showing the configuration of a call charge transfer apparatus for a mobile communication system according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , the call charge transfer apparatus comprises a plurality of mobile terminals  100 , one or more mobile base stations  200 , one or more mobile switching centers  300 , and a billing server  400 . 
     In a call-connected state, a calling mobile terminal  100  transmits a ‘call transfer request’ signal to a called mobile terminal  100 . After reception of the ‘call transfer request’ signal, the called mobile terminal  100  transmits in reply a ‘call transfer accept’ signal to the calling mobile terminal  100 . Under a call transfer agreement between the calling and called mobile terminals  100 , the billing server  400  switches the paying party registered thereat to the called mobile terminal  100 . 
     Additionally, under the call transfer agreement, the calling and called mobile terminals  100  terminate the current call connection. The called mobile terminal  100  then places a new call to the calling mobile terminal  100 , thereby resulting in the call transfer through a call reconnection. 
     A mobile base station  200  makes wireless connections between calling and called mobile terminals  100  in a service area to transmit/receive communication signals including ‘call setup request’ signals and associated reply signals. 
     A mobile switching center  300  connects to mobile base stations  200 , establishes communication paths in response to ‘call setup request’ signals, and controls and monitors the billing server  400  to charge fees on paying parties on a communication time basis. In the present exemplary embodiment, the mobile switching center  300  controls the switching of a paying party when a corresponding ‘call transfer accept’ signal is received in reply to a ‘call transfer request’ signal. 
     The billing server  400  connects to a mobile switching center  300 , and charges fees to paying parties selected under the control of the mobile switching center  300 . In the present exemplary embodiment, when a paying party is changed according to a call transfer agreement between two mobile terminals  100 , the billing server  400  switches the paying party in response to a control signal from the mobile switching center  300 . 
       FIG. 3  is a flow chart illustrating a method of call charge transfer between mobile terminals according to an exemplary embodiment of the present invention. 
     Referring to  FIGS. 2 and 3 , a mobile switching center  300  determines whether a call connection request exists at step S 201 . If a call connection request exists, the mobile switching center  300  identifies a calling mobile terminal  100  associated with the call connection request, and transmits a ‘call setup request’ signal to a corresponding called mobile terminal  100  (S 202 ). The called mobile terminal  100  transmits in reply a ‘call setup accept’ signal to the calling mobile terminal  100 , which then analyzes received information to set up a communication path according to the control of the mobile switching center  300  at step S 203 . The calling mobile terminal  100  then establishes a call connection to the called mobile terminal  100  at S 204 . After establishment of the call connection, the calling and called mobile terminals  100  may display, respectively, calling and called party information related with fee payment on screens, to inform the calling and called users of which is the calling party and which the called party. 
     During the call, the calling mobile terminal  100  determines whether a ‘call charge transfer’ request is input by the calling user at step S 205 . If a ‘call charge transfer’ request is not input, the calling mobile terminal  100  performs step S 208  (described later) to continue conversation. 
     If the ‘call charge transfer’ request is input, the calling mobile terminal  100  transmits a ‘call charge transfer request’ signal through the mobile switching center  300  to the called mobile terminal  100 , and determines whether a ‘call charge transfer accept’ signal is received from the called mobile terminal  100  in reply to the ‘call charge transfer request’ signal at step S 206 . The called user may manipulate a ‘call transfer’ menu displayed on the screen of the called mobile terminal  100  with direction keys to transmit the ‘call charge transfer accept’ signal. 
     If the ‘call charge transfer accept’ signal is not received, the calling mobile terminal  100  performs step S 208  to continue conversation. 
     If the ‘call charge transfer accept’ signal is received, the paying party is switched from the calling mobile terminal  100  to the called mobile terminal  100  at step S 207 . The existing call is maintained in a call charge transferred state at step S 208 . After the call charge transfer, to report the switch of the paying party a called party indicator may be displayed on the screen of the calling mobile terminal  100  and a calling party indicator may be displayed on the screen of the called mobile terminal  100 . In addition, because of the switch of the paying party, call-related fees prior to the switch of the paying party are imposed on the former calling mobile terminal  100 , and call-related fees after the switch of the paying party are imposed on the former called mobile terminal  100 . 
       FIGS. 4A to 4B  are flow diagrams illustrating a method of call transfer between mobile terminals according to an exemplary embodiment of the present invention. 
     Referring to  FIGS. 2 ,  4 A and  4 B, a first mobile terminal  100 A transmits the phone number of a second mobile terminal  100 B to a first base station  200 A in step S 301 . The first base station  200 A transmits a ‘call setup request’ signal related with the received phone number to a first mobile switching center  300 A in step S 302 . The first mobile switching center  300 A assigns a channel to the first mobile terminal  100 A via the first base station  200 A in step S 303 , and the first mobile terminal  100 A reports preparation of the channel to the first base station  200 A in step S 304 . 
     The first mobile switching center  300 A transmits the ‘call setup request’ signal to a second mobile switching center  300 B that manages the phone number of the second mobile terminal  100 B in step S 305 . The second mobile switching center  300 B forwards the ‘call setup request’ signal to the second mobile terminal  100 B via a second base station  200 B in step S 306 . The second mobile terminal  100 B transmits a ‘call setup accept’ signal in response to the ‘call setup request’ signal to the second base station  200 B in step S 307 . The second base station  200 B forwards the received ‘call setup accept’ signal to the second mobile switching center  300 B in step S 308 . On the basis of the ‘call setup accept’ signal, the second mobile switching center  300 B assigns a channel for the call to the second mobile terminal  100 B via the second base station  200 B in step S 309 , and the second mobile terminal  100 B reports preparation of the channel to the second base station  200 B in step S 310 . 
     After the preparation procedure described above, a call connection is established between the first mobile terminal  100 A and second mobile terminal  100 B in step S 311 , enabling conversation between the calling and called users. 
     After the call connection, the first mobile terminal  100 A and second mobile terminal  100 B display calling/called party information related with call charges on screens thereof to inform which is the calling party and which the called party. That is, a calling party indicator is displayed on the first mobile terminal  100 A and a called party indicator is displayed on the second mobile terminal  100 B. 
     If the calling user issues a ‘call transfer’ request, the first mobile terminal  100 A transmits a ‘call transfer request’ signal to the first base station  200 A in step S 312 , which then forwards the ‘call transfer request’ signal to the first mobile switching center  300 A in step S 313 . 
     The calling user may manipulate a ‘call transfer’ menu displayed on the screen of the first mobile terminal  100 A with direction keys to issue the ‘call transfer’ request. 
     The first mobile switching center  300 A delivers the ‘call transfer request’ signal, via the second mobile switching center  300 B and second base station  200 B, to the second mobile terminal  100 B in a call with the first mobile terminal  100 A in step S 314 . The second mobile terminal  100 B determines whether a ‘call transfer accept’ signal is input by the called user in reply to the delivered ‘call transfer request’ signal in step S 315 . 
     If a ‘call transfer accept’ signal is not input, the second mobile terminal  100 B performs step S 311 . 
     If the ‘call transfer accept’ signal is input, the second mobile terminal  100 B transmits a ‘call transfer accept’ signal to the second base station  200 B in step S 316 , which then forwards the ‘call transfer accept’ signal to the second mobile switching center  300 B in step S 317 . Upon reception of the ‘call transfer accept’ signal, the second mobile switching center  300 B transmits a ‘call termination’ signal to the first mobile terminal  100 A via the first mobile switching center  300 A and first base station  200 A in step S 318 A, and also transmits a ‘call termination’ signal to the second mobile terminal  100 B via the second base station  200 B in step S 318 B. After reception of the ‘call termination’ signal, the second mobile terminal  100 B terminates the current call, and transmits the phone number of the first mobile terminal  100 A to the second base station  200 B in step S 319 , which then transmits a ‘call setup request’ signal to the second mobile switching center  300 B in step S 320 . On the basis of the ‘call setup request signal, the second mobile switching center  300 B assigns a channel for the call to the second mobile terminal  100 B via the second base station  200 B in step S 321 , and the second mobile terminal  100 B reports preparation of the channel to the second base station  200 B in step S 322 . To setup a call connection with the first mobile terminal  100 A, the second mobile switching center  300 B transmits the ‘call setup request’ signal to the first mobile switching center  300 A in step S 323 , which forwards the ‘call setup request’ signal to the first mobile terminal  100 A via the first base station  200 A in step S 324 . Upon reception of the ‘call setup request’ signal, the first mobile terminal  100 A transmits in reply a ‘call setup accept’ signal to the first base station  200 A in step S 325 , which then forwards the ‘call setup accept’ signal to the first mobile switching center  300 A in step S 326 . The first mobile switching center  300 A assigns a channel for the call to the first mobile terminal  100 A via the first base station  200 A in step S 327 , and the first mobile terminal  100 A reports preparation of the channel to the first base station  200 A in step S 328 . 
     In the call connection for the call charge transfer, the call connection may be made without a call waiting tone. Guide messages are preferably displayed on the screens to indicate the progress of the call transfer. 
     After the preparation procedure described above, a call connection is established between the first mobile terminal  100 A and second mobile terminal  100 B in step S 329 , enabling conversation between the calling and called users. A calling party indicator may be displayed on the second mobile terminal  100 B and a called party indicator may be displayed on the first mobile terminal  100 A. 
       FIGS. 5A to 5K  are screen representations illustrating steps of call transfer between mobile terminals according to exemplary embodiments of the present invention. 
     After establishment of a call connection, a calling party indicator  301  and a ‘call transfer’ menu item  303  are displayed on a screen  300  of a calling mobile terminal as shown in  FIG. 5A , and a called party indicator  201  and a ‘call transfer’ menu item  203  are displayed on a screen  200  of a called mobile terminal as shown in  FIG. 5B . When the calling user selects the ‘call transfer’ menu item  303 , a message asking whether to issue a call transfer request is displayed on the screen  300  as shown in  FIG. 5C . If the calling user issues a call transfer request, the calling mobile terminal transmits a ‘call transfer request’ signal to the called mobile terminal, and displays on the screen  300  a message indicating a wait for a reply corresponding to the ‘call transfer request’ signal as shown in  FIG. 5D . Upon reception of the ‘call transfer request’ signal, the called mobile terminal displays on the screen  200  a message asking whether to accept the call transfer request as shown in  FIG. 5E . If the called user accepts the call transfer request, the called mobile terminal transmits a ‘call transfer accept’ signal, and displays on the screen  200  a message indicating a wait for call transfer as shown in  FIG. 5F . 
     The calling mobile terminal also displays on the screen  300  a message indicating a wait for call transfer as shown in  FIG. 5G . Upon completion of the call transfer, the calling and called mobile terminals display on the screens  300  and  200  messages indicating call transfer completion as shown in  FIGS. 5H and 5I , respectively. In addition, the roles of the calling and called mobile terminals are exchanged with each other. That is, a calling party indicator  207  is displayed on the screen  200  of the new calling mobile terminal as shown in  FIG. 5J , and a called party indicator  307  is displayed on the screen  300  of the new called mobile terminal as shown in  FIG. 5K . 
     As apparent from the above description, exemplary embodiments of the present invention provide a method of call charge transfer between mobile terminals wherein calling/called party information is displayed on each screen during a call so that users can visually identify which is the calling party and which the called party. 
     In addition, during a call between mobile terminals, the called user can accept a call transfer request of the calling user to transfer call-related charges to the called party, thereby enabling flexible and efficient billing. For example, when the calling user pays 30 units of money per 10 seconds and the called user pays 9 units per 10 seconds, the users can reduce call-related charges by selecting a call transfer menu item without termination of an ongoing call and a subsequent call by the called user. 
     While exemplary embodiments of the present invention have been shown and described in this specification, it will be understood by those skilled in the art that various changes or modifications of the embodiments are possible without departing from the spirit and scope of the invention as defined by the appended claims including the full scope of equivalents thereof.