Abstract:
An apparatus and method for secured redialing in a telephone is disclosed. The redial feature is made secure by establishing a prescribed time for storing in memory a last number dialed. Once the prescribed time has elapsed, the number is erased from the telephone memory. The apparatus and method can also prevent storing in memory the last dialed number.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to telephone apparatus and an associated method of secured redialing in a telephone. 
     2. Description of the related art 
     Redial is a well-known telephone function that automatically recalls from memory and redials the last number called. This function is usually invoked by pressing a redial button. While this feature provides convenience to a user, there is a serious drawback in that the last number called is stored in the memory of the phone, so that any person with access to the phone can redial it, or learn the number through a display provided in the phone. Hence, it often occurs that even secret numbers such as those required for tele-banking, for example, may be inadvertently displayed. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a method of secured redialing in a telephone. 
     It is another object of the present invention to provide a method of setting a predetermined time during which the redial function will redial the last number called, and automatically delete the last number called from memory when the predetermined time elapses. 
     According to the present invention, a method of secured redialing in a telephone including a memory, generally comprises the steps of setting a predetermined time during which a last number called will be retained in the telephone memory, and storing the last number called into the memory for the predetermined time. 
     The present invention will now be described more specifically with reference to the drawings attached only by way of example. 
    
    
     BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS 
     FIG. 1 is a block diagram for illustrating the structure of a telephone for the present invention; 
     FIG. 2 is an illustration of a switch for setting the time to retain the last number called according to the present invention; 
     FIG. 3 is a flow chart for illustrating the steps of setting the predetermined time to retain the last number called according to the present invention; and 
     FIG. 4 is a flow chart for illustrating the steps of storing the last number called in the telephone memory according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Throughout the drawings detailed descriptions of the conventional components of a telephone are omitted as they are not essential to the invention and would therefore detract from describing the present invention. 
     Referring to FIG. 1, the telephone includes a CPU  100 , memory  110 , key input part  120 , dialing device  130 , ring generator  140 , voice transceiver  150  and power supply  160 . The CPU  100  controls all telephone functions including the inventive secured redial function. The telephone also includes a timer to check the time set for redialing the last stored number. The memory  110  stores the program and data necessary to execute the procedures according to FIGS. 3 and 4. In addition, the memory  110  stores the last number called for a prescribed time under the control of the CPU  100 . The key input part  120  includes a plurality of numeric keys for dialing together with a redial key. In one embodiment, the key input part  120  may also include a switch for setting the prescribed time to retain the last number called in the memory, as shown in FIG.  2 . In this embodiment, the switch has three modes, which include a redial-off mode for suppressing the redialing function, a prescribed retaining mode for retaining the last number called in the memory  110  only for a prescribed time, and a permanent retaining mode for continuously retaining the last number called in the memory  110  until another number is inputted. 
     The dialing device  130  dials the number inputted through the key input part  120  or retrieved by the redial key from the memory  110  under the control of the CPU  100 . The ring generator  140  generates a ring signal. The voice transceiver  150  transmits and receives voice signals. The power supply  160  supplies power to the CPU  100 , memory  110 , key input part  120 , dialing device  130 , ring generator  140 , and voice transceiver  150 . The power supply  160  may be a commercial source obtained through the telephone line or a battery for a cordless or mobile phone. 
     The setting of the prescribed time to retain the last number called will be described with reference to FIGS. 1 and 3. The CPU  100  determines in step  310  whether the program mode is selected by the key input part  120 . When the program mode is selected, it is then determined in step  320  whether the function of setting the prescribed time to retain the last number called is selected by the key input part  120 . If it is not selected, the CPU  100  performs the corresponding function selected by the key input part  120  in step  330 . However, if it is selected, it is determined in step  340  whether the time to retain the last number called is inputted by the key input part  120 . When the time for retaining the last number called is inputted, it is set by the CPU  100 . For example, if the inputted data is “00”, the last number called will not be stored in the memory. If, however, the inputted data is “**”, the last number called is retained in the memory until another number is inputted. 
     The process of secured redialing will be described with reference to FIGS. 1 and 4. The CPU  100  determines in step  410  whether a phone number is dialed through the key input part  120 . When a phone number is dialed, determining whether a predetermined redial time for retaining the last number called is set in step  420 . When the predetermined redial time is set, the dialed phone number is stored into the memory  110  in step  430 . The CPU  100  checks by the internal timer whether the predetermined redial time has elapsed in step  440 . When the predetermined redial time has elapsed, the CPU  100  deletes the last number called from the memory  110  in step  450 . That is, the last number called is retained in the memory  110  only for a prescribed time. 
     Thus, the user may advantageously retain the last number called in the memory for only a desired time in order to prevent it from being inadvertently exposed. In addition, if the predetermined time is set to “0” for security reasons, the last number called is never stored in the memory. 
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and have been described herein in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.