Abstract:
A cellular telephone apparatus capable of establishing and maintaining a call even in case of a failure in call establishment or a call due to a busy state of a called party or a communications channel disorder such as congestion or received wave level shortage. In response to a request for a call origination for a destination telephone number, a call is originated for the destination telephone number. In case of a failure in the call origination, a call termination process is executed and then the call origination is retried. Once a call is established after the call origination, in response to a detection of disconnection of the call caused not by a user but by a channel disorder, a call termination process executed. A call is originated for the same telephone number as a destination telephone number of the disconnected call. In an embodiment, the retrying is put off while a received wave level is less than a predetermined level. If a count of said call origination reaches a predetermined count value, then the retrying is stopped.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a mobile telephone and, more specifically, to a technique for establishing and maintaining a call by automatic redialing in case of a failure in call establishment or a call due to a communications channel disorder such as congestion or weak wave (i.e., received wave level shortage).  
           [0003]    2. Description of the Prior Art  
           [0004]    There are a variety of telephone sets that can automatically dial one of telephone numbers previously stored in memory by the user. Some of them redial the last called phone number in response to a predetermined input. Some others dial a phone number either specified by a predetermined operation by the user or associated with an abbreviated number input by the user. Also, U.S. Pat. No. 5,742,666 discloses an emergency mobile telephone. In this system, automatic dialing of an emergency telephone number is initiated by the user pressing a dedicated push button on the cellular telephone handset, or alternatively, upon the occurrence of an accident which is detected by the cellular telephone.  
           [0005]    However, there has not been such a cellular telephone as utilizes the automatic redialing function to cope a failure in call establishment such as a busy state of the called party, a congestion or weak wave and to cope with a failure in connection during a call due to congestion or weak wave.  
           [0006]    Therefore, it is an object of the invention to provide a technique for establishing and maintaining a call by automatic redialing in case of a failure in call establishment or a call due to a busy state of the called party or a communications channel disorder such as congestion or weak wave.  
         SUMMARY OF THE INVENTION  
         [0007]    The problems of a failure in call establishment or a call due to a busy state of the called party or a communications channel disorder are overcome in accordance with an aspect of the invention. In response to a request for a call origination for a destination telephone number, a call is originated for the destination telephone number. In case of a failure in the call origination, a call termination process is executed and then the call origination is retried.  
           [0008]    In a preferred embodiment, the retrying of the call origination is put off while a received wave level is less than a predetermined level.  
           [0009]    If a count of said call origination reaches a predetermined count value, then the retrying is stopped.  
           [0010]    If the failure is due to a busy state of a called telephone terminal identified by the destination telephone number, a call is originated for a substitution telephone number as the retrying operation. The substitution telephone number is one of telephone numbers associated with a called party identified by the destination telephone number in a telephone directory table. The substitution telephone number is different from the last called telephone number.  
           [0011]    If a count of said call origination reaches a predetermined count value, then the retrying is stopped.  
           [0012]    Once a call is established after the call origination, in response to a detection of disconnection of the call caused not by a user but by a channel disorder, a call termination process executed. A call is originated for the same telephone number as a destination telephone number of the disconnected call.  
           [0013]    According to another aspect of the invention, a cellular telephone apparatus capable of establishing and maintaining a call even in case of a failure in call establishment or a call due to a busy state of a called party or a communications channel disorder is provided in the same way as described above.  
           [0014]    According to further aspect of the invention, there is provided a portable system including a cellular telephone means capable of establishing and maintaining a call even in case of a failure in call establishment or a call due to a busy state of a called party or a communications channel disorder. The cellular telephone means has the same features as the cellular telephone apparatus described above. The portable system may include a GPS (global positioning system) or navigation system. The portable system may be a laptop computer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0015]    The features and advantages of the present invention will be apparent from the following description of an exemplary embodiment of the invention and the accompanying drawings, in which:  
         [0016]    [0016]FIG. 1 is a schematic block diagram showing an arrangement of a cellular telephone set according to an illustrative embodiment of the invention;  
         [0017]    [0017]FIG. 2 is a diagram showing an example of a telephone directory table stored in the nonvolatile memory  80  of FIG. 1;  
         [0018]    [0018]FIG. 3 is a flowchart showing an operation of the controller  30  under the control of programs (not shown) stored in ROM  32  and executed when a call is initiated and continues according to the principles of the invention;  
         [0019]    [0019]FIG. 4 is a part of flowchart which is executed in place of any of steps  112 ,  126  and  145 ; and  
         [0020]    [0020]FIG. 5 is a flowchart showing an operation of the controller  30  under the control of a program (not shown) stored in ROM  32  and executed in response to a request for data transfer from an internal or external host system.  
     
    
       [0021]    Throughout the drawing, the same elements when shown in more than one figure are designated by the same reference numerals.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    [0022]FIG. 1 is a schematic block diagram showing an arrangement of a cellular telephone set according to an illustrative embodiment of the invention. In FIG. 1 the cellular telephone set  1  comprises an antenna  10 , a radio transceiver  12 , a speech portion  20  for processing speech signals between the user of this telephone set  1  and the communication opponent during a call, a controller  30  for controlling the overall operation of the telephone set  1 , an input device  40  for permitting the user to input control data, a display device  50  for displaying information passed from the controller  30 , a loudspeaker  60  for providing an audio output according to an audio signal from the speech portion  20 , a microphone  70  for converting a user&#39;s voice into an audio signal passed to the speech portion  20  and a nonvolatile memory  80  for storing data such as a telephone directory table (detailed later). The radio transceiver  14  includes an electromagnetic wave level detector  14  for detecting the level of received electromagnetic wave signal. The speech portion  20  may optionally include a speech synthesizer  22  for synthesizing one of prepared messages for the user to inform the user of the current state of the cellular telephone set  1 . If the cellular telephone set  1  is intended for mounting in a vehicle, the speech portion  20  preferably comprises a hands-free speech communication system.  
         [0023]    The cellular telephone set  1  may further comprise a data communication interface (IF)  90  for enabling the telephone set  1  to communicate with an internal or external host system such as a microcomputer (not shown). The cellular telephone set  1  may be a part of a portable or laptop computer (not shown). If the telephone set  1  is not incorporated in such a laptop computer, the external interface (the opposite side of the side connected with the controller  30 ) of the data communication IF  90  is preferably a standard interface such as an RS-232C port. The controller  30  includes a read only memory (ROM)  32  for storing programs under the control of which the controller  30  operates.  
         [0024]    The cellular telephone set  1  may further comprises an interface (IF)  95  through which the telephone set  1  can input data from, for example, a sensor (not shown) for detecting an operation of an air bag and/or a GPS (global positional system) receiver (not shown) or a car or personal navigation system (not shown). The cellular telephone set  1  and a GPS receiver or personal navigation system may be incorporated into a single system.  
         [0025]    [0025]FIG. 2 is a diagram showing an example of a telephone directory table stored in the nonvolatile memory  80  of FIG. 1. In FIG. 2, the telephone directory table at least comprises an ID field that contains an ID (identifier) for identifying a person or party listed in the table and a telephone number field that contains at least one corresponding telephone number.  
         [0026]    [0026]FIG. 3A is a flowchart showing an operation of the controller  30  under the control of a call-origination program (not shown) stored in ROM  32  and executed when a call is initiated according to the principles of the invention. FIG. 3B is a flowchart showing an operation of the controller  30  under the control of a call-maintenance program (not shown) stored in ROM  32  executed during a call according to the principles of the invention. The call-origination program is invoked in response to a call-origination request for a specified address (or telephone number) from the input device  40 , the not-shown sensor for detecting the operation of a not-shown air bag or the communication IF  90  (i.e., the host system connected with the IF  90 ). In FIG. 3, the flow ends terminated with an encircled letter “A” and “B” are to be interconnected with one another.  
         [0027]    In FIG. 3A, step  100  sends a call-origination command for the specified (or destination) telephone number to the radio transceiver  12 . Then, decision step  102  wait for a response from the transceiver  12 . If a call success signal is received, the control is passed to step  104 , where the controller  30  stores the destination telephone number, the origination time and date, and a code indicative of the call success in the nonvolatile memory  80 . In this case, the controller  30  may display the stored information on the display device  50 . Thereafter, the control is passed to step  140  of FIG. 3B.  
         [0028]    If the controller  30  receives a busy signal from the radio transceiver  12  in step  102 , then the control is passed to step  108 , where the controller  30  stores the destination telephone number, the origination time and date, and a code indicative of the busy state in the nonvolatile memory  80 . In this case, the controller  30  may display the stored information on the display device  50 . Then, step  110  terminates the call-origination process. Step  112  makes a test to see if the received wave level is enough for a call (i.e., not less than a predetermined level), and wait till the received wave level becomes enough. If so, step  114  sends an origination command for a substitution telephone number, if any, or for the same telephone number, if not. Specifically, the controller  30  searches the telephone number field of the telephone directory table of FIG. 2 for the destination telephone number used in step  100  (the last called telephone number). If there are two or more telephone numbers in the found telephone number field (as shown in a record “BCDE” of the directory table of FIG. 2), then the controller  30  sends a call-origination command for a telephone number located next to the last called telephone number in the found telephone number field. Then, step  116  makes a test to see if a retrial counter (not shown) Cr equals a first preset retrial count Cr 1 . If so, then the call origination operation ends. Otherwise, the controller  30  increments the retrial counter Cr in step  118  to return to step  102 .  
         [0029]    In this way, if a destination or a called party has two or more telephone terminals and a called one of the telephone terminals is busy, the cellular telephone set  1  scans the telephones terminals one after another, which enable the user to be connected to a first released telephone terminal of the called party effectively.  
         [0030]    It should be noted that step  112  may be omitted. It is especially true if the cellular telephone set  1  is of a type not mounted in a vehicle but carried by a person. This is because the radio wave reception conditions around the telephone set of such a type will change gradually.  
         [0031]    If the controller  30  receives a channel disorder signal from the radio transceiver  12  in step  102  or if the controller  30  receives no response from the radio transceiver  12  for a time period exceeding an allowable time period in step  120 , then the control is passed to step  122 . The channel disorder signal is either a congestion signal indicative of the congestion of the communication channel leading to the destination or a weak wave signal indicative of the received wave signal being too weak for a call. In step  122 , the controller  30  stores the destination telephone number, the origination time and date, and a code indicative of either the congestion or the weak wave (i.e., received wave level shortage) in the nonvolatile memory  80 . Again, the controller  30  may display the stored information on the display device  50 . Then, step  124  terminates the call-origination process. Step  126  makes a test to see if the received wave level is enough for a call (i.e., not less than the predetermined level), and wait till the received wave level becomes enough. If so, step  128  sends an origination command for the same telephone number as used in step  100 . Then, step  130  makes a test to see if a retrial counter (not shown) Cr equals a second preset retrial count Cr2. If so, then the call-origination operation ends. Otherwise, the controller  30  increments the retrial counter Cr in step  132  to return to step  102 .  
         [0032]    In this way, if communication channels leading to the telephone terminal of the called telephone number is congested or if the level of the received wave signal is too weak to establish a connection, the cellular telephone set  1  waits till the wave signal level becomes enough for connection, and retries to originate a call to the same telephone number when the wave signal level becomes enough for connection.  
         [0033]    It should be noted that the level checking step  126  might be omitted in case of the congestion of communication channels. It is also noted that the first and second preset retrial counts Cr1 and Cr2 may be either equal to or different from each other.  
         [0034]    Once a call is established at step  104 , then the control is passed to step  140  of FIG. 3B. Step  140  makes a test to see if a call termination signal is issued by the user pressing a predetermined button (not shown) of the input device  40 . If so, then step  141  sends a control signal indicative of a call termination to the radio transceiver  12 , executes a call termination process and ends the operation of FIG. 3B. Otherwise, step  142  makes another test to see if a waiting signal is received from the radio transceiver  12 . If not, the control is passed to step  140 . If a waiting signal is received in step  142 , Then step  143  stores the destination telephone number, the origination time and date, and a code indicative of the call waiting state in the nonvolatile memory  80 . Again, the controller  30  may display the stored information on the display device  50 . Then, step  144  terminates the call-origination process. Step  145  makes a test to see if the received wave level is enough for a call (i.e., not less than a predetermined level), and wait till the received wave level becomes enough. If so, step  146  sends an origination command for the same telephone number as the last called telephone number, and ends the operation of FIG. 3B. Otherwise, the controller  30  waits till the received wave level becomes enough for a call.  
         [0035]    In this way, if the connection between the user and the destination telephone terminal is disconnected due to weak wave, the cellular telephone set  1  waits till the wave signal level becomes enough for connection, and retries to originate a call to the same telephone number when the wave signal level becomes enough for connection.  
         [0036]    In the above description, each of wave level checking steps  112 ,  126  and  145  may be replaced with steps  150  and  152  of FIG. 5. That is, as any of steps  112   a,    126   a  and  145   a,  the controller  30  may obtain data indicative of the received wave signal level and store the data in the memory  80  in step  150 ; and make a test in step  152  to see if the received wave signal level is enough for a call (i.e., not less than the predetermined level), to proceed the following step if so or to return to step  150  otherwise.  
         [0037]    The received wave signal level can be obtained from the wave level detector  14  in the radio transceiver  12 . If the cellular telephone set  1  is incorporated with a GPS system or a navigation system, the decision of whether the received wave signal level is enough for a call may be made not by using the wave level detector  14  but by using the GPS or navigation system.  
         [0038]    Specifically, if the GPS system is used, the controller  30  receives information on the number of satellites, satellite numbers, reception time and date, the position by longitude and latitude, etc. (and stores the information in memory  80  in step  150 ). The controller  30  makes the above decision according to the reception condition of the GPS system in step  112 ,  126 ,  145  or  152 .  
         [0039]    If the navigation system is used, the controller  30  receives information on the kind of the ground facility or the topography where the user is located (and stores the information in memory  80  in step  150 ). The controller  30  makes the above decision according to the received information and a list of kinds of ground facilities or topographies where radio waves are hard and/or easy to receive in step  112 ,  126 ,  145  or  152 .  
         [0040]    Alternatively, if the cellular telephone set  1  is of a vehicle-carried type that is not provided with a GPS or navigation system, then the cellular telephone set  1  may use an external GPS or navigation system.  
         [0041]    The cellular telephone set  1  may be incorporated in a portable or laptop computer or host system (not shown). If a data transmission is to be achieved to or from an external or internal host system, the controller  30  preferably transfers requested data stored in the memory  80  to the external or internal host system as shown in steps  160  and  162  of FIG. 5 instead of displaying or storing the requested data in steps  104 ,  108 ,  122 ,  143  and  160 .  
         [0042]    The speech portion  20  may be provided with a speech synthesizer  22 . This enables the call status-displaying and/or storing steps  104 ,  108 ,  122  and  143  to inform the user of the call status in voice.  
         [0043]    After call termination steps  110 ,  124  and  144 , timer routines may be inserted. In this case, the timer routines are preferably arranged such that the expiration time of each timer routine can be preset by the user.  
         [0044]    Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.