United States Patent
`Ise
`Oct. 26, 1993
`[45] Date of Patent:
`
`[11] Patent Number:
`
`5,257,307
`
`[191
`
`llllll|l||||l|lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll
`USO05257307A
`
`OTHER PUBLICATIONS
`
`Electronics International, Paging System Broadcasts
`Nationwide on FM Radio Channel, Jan. 1979, p. 68.
`“NTT Paging System” by Masahiro Wada, May 1, 1989
`NTT Review pp. 45-53.
`
`Primary Examiner—Jin F. Ng
`Assistant Examim-:r—George J. Oehling
`[57]
`ABSTRACT
`
`A radio pager system and pager terminal apparatus used
`in the system are disclosed. A pager signal to be trans-
`mitted includes destination information‘ and message
`specifying information for specifying a message to be
`transmitted. The pager terminal apparatus includes a
`receiver for receiving an incoming pager signal, a detec-
`tor for detecting that the received pager signal is a
`signal destined for the pager terminal apparatus, an
`extracting circuit
`for extracting message specifying
`information from the pager signal transmitted to the
`pager terminal apparatus and message displaying appa-
`ratus responsive to the extracted message specifying
`information for displaying a message corresponding to
`the extracted message specifying information in a visu-
`ally recognizable manner. The radio pager system in-
`cludes the above pager terminal apparatus, a station for
`transmitting via radio a pager signal, and transmission
`terminal apparatus for supplying the destination infor-
`mation and the message information to the station. The
`data to be transmitted is not the body of the message but
`message specifying information, so that the amount of
`data to be transmitted is reduced and the communica-
`tion is kept secret.
`
`15 Claims,'4 Drawing Sheets
`
`[54] RADIO PACER SYSTEM WHICH
`TRANSMITS SECRET CODED MESSAGES
`FROM A CALLER TO A PAGER TERMINAL
`APPARATUS
`
`[75]
`
`Inventor: Masahiro Ise, Kashihara, Japan
`
`[73] Assignee:
`
`Sharp Kabushiki Kaishu, Osaka,
`Japan
`
`[21] Appl. No.2 650,094
`
`[22] Filed:
`
`Feb. 4, 1991
`
`Foreign Application Priority Data
`[30]
`Feb. 7, 1990 [JP]
`Japan .................................... 2-28684
`Feb. 7, 1990 [JP]
`Japan .................................. .. 2-28685
`Feb. 7, 1990 [JP]
`Japan .................................... 2-28686
`
`Int. Cl.5
`[51]
`.............................. .. H04M 11/00
`
`[52] U.S. Cl. . . . . . . . . . .. .
`. . . . . . .. 379/57; 340/825.44
`[58] Field of Search .............. .. 379/56, 57; 340/825.44
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3/1987 Sebestyen ....................... .. 340/3ll.l
`Re. 32,365
`6/1982 Levine .. . . . . . . .
`. . . . .. 379/57
`4,336,524
`4,490,579 12/1984 Godoshian
`.... .. 379/57
`4,994,797
`2/1991 Breeden ..... ..
`379/57 X
`5,049,874 9/199]
`Ishida et al.
`340/825.44
`5,066,949 11/1991 Breeden et al.
`................ .. 379/57 X
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`8/1983 European Pat. Off.
`0086255
`1/1988 European Pat. Off.
`0251477
`3/1990 European Pat. Off.
`0360228
`60-220632 11/1985 Japan .
`61-274527 12/1986 Japan .
`
`.
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`
`U.S. Patent
`
`Oct. 26, 1993
`
`Sheet 1 of 4
`
`5,257,307
`
`FIG. 1 PRIOR ART
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`FIG. 2
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`PRIOR ART
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`U.S. Patent
`
`Oct. 25, 1993
`
`Sheet 4 of 4
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`5,257,307
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`FIG. 5
`
`DISPLAY
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`SIGNAL
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`5
`
`

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`1
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`5,257,307
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`RADIO PAGER SYSTEM WHICH TRANSMITS
`SECRET CODED MESSAGES FROM A CALLER TO
`A PACER TERMINAL APPARATUS
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`
`The invention relates generally to radio pager sys-
`tems and, more particularly, it relates to improvements
`in a radio pager system and a pager terminal apparatus
`used in this system, in which a registered caller accesses
`a pager base station over the public telephone line, and
`calls a desired pager terminal via the pager base station.
`2. Description of the Related Art
`A pager system is one of the systems for calling a
`person who is absent. A radio pager system particularly
`provides a service of calling a person by radio who is
`absent, and transmitting a message to him. One example
`is “pocket bell service” provided by Nippon Telegraph
`& Telephone Corporation (NTT) in Japan.
`FIG. 1 is a typical diagram showing the configuration
`of a conventional pager system. Referring to FIG. 1, the
`radio pager system includes a public telephone line 1
`used by a caller, an exchange 2, a pager base station 3
`for transmitting a pager signal, and a pager terminal
`apparatus 4, which a callee carries about, for receiving
`a pager signal from the pager base station 3.
`The system shown in FIG. 1 operates as follows. The
`registered caller accesses the pager base station 3 over
`the public telephone line 1. The pager base station 3
`gives the caller instructions as to the procedure of call-
`ing in accordance with a predetermined program. The
`caller inputs a calling code assigned in advance, and
`stored in the pager terminal apparatus carried by the
`callee of concern by way of push-buttons of a telephone
`and the like, in accordance with the given instructions.
`The calling code is temporarily stored in the pager base
`station. The caller further inputs a message which he
`intends to transmit to the callee. The pager base station
`3 radio-transmits the given calling code and message in
`a predetermined communication format.
`The input of the message from the caller is conducted
`as follows. In a control computer of the pager base
`station 3, there are stored standardized sentences to
`each of which a code is assigned for specifying the
`sentence, and a table for converting the given code to
`character‘ strings of the standardized sentence. The
`caller selects a desired standard sentence referring to a
`table identical with this converting table, and assigns a
`code corresponding to the selected standard sentence
`by way of push-buttons and so on. The pager base sta-
`tion 3 converts the inputted code to a character string in
`accordance with the converting table. The base station
`3 further radio-transmits the message including the
`character strings obtained by conversion along with the
`assigned calling code.
`FIG. 2 shows one example of a communication for-
`mat. Referring to FIG. 2, data to be transmitted in-
`cludes a synchronous signal bit string “SYNC”, a call-
`ing code “ADDRESS”, and a transmission message
`“MESSAGE” including character strings from the
`caller.
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`In such a radio pager system, a short calling code
`inputted is converted to a message at the base station, so
`that it is possible to cut down the amount of key manip-
`ulation by the caller. However, a pager radiowave
`transmitted from the base station includes data con-
`verted to character strings. Therefore, in spite of the
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`2
`fact that there is a need to limit the amount of data in
`order to keep the traffic in an appropriate range for
`smooth communication, the amount of data transmitted
`is large. As character strings of a message are transmit-
`ted, as they are, by a radiowave which anyone can
`pickup, it is impossible to keep communication secret.
`The table for converting the fixed form of sentence
`code to character strings of a message is stored within
`the computer of the pager base station. Therefore, a
`large amount of work is needed for making converting
`tables fully corresponding to the needs of a multiplicity
`of subscribers. Even the message frequently used be-
`tween a caller and a callee needs to have the whole
`sentence inputted as stated above if it is not included in
`the converting table of the base station. While it seems
`possible that this problem may be solved using an indi-
`vidual converting table with respect to a respective
`subscriber,
`it is technically impossible to prepare an
`individual converting table for each subscriber in the
`conventional pager base station.
`If each user inputs all the messages without using
`such a converting table, he can transmit any messages.
`In this case, however, not only the amount of operation
`by the caller is increased, but also secret communication
`is prevented.
`~
`SUMMARY
`
`Therefore, an object of the present invention is to
`provide a pager terminal apparatus and a radio pager
`system which reduces the amount of data transmitted
`and which subsequently allow for increase in the num-
`ber of subscribers.
`
`Another object of the present invention is to provide
`a pager terminal apparatus and a radio pager system
`which reduces the amount of data transmitted and the
`amount of key operation required for message transmis-
`sion.
`
`Still another object of the invention is to provide a
`pager terminal apparatus and a radio pager system
`which permits secret communication as well as reduc-
`ing the amount of data transmitted and the number of
`key operations.
`The pager terminal apparatus in accordance with the
`present invention includes a receiver for receiving an
`incoming pager signal. The pager signal includes desti-
`nation information representing the destination, and
`message specifying information for specifying a mes-
`sage to be transmitted to the destination. The pager
`terminal apparatus further includes a detector for de-
`tecting that the pager signal received by the receiver is
`a signal transmitted to itself, and outputting a predeter-
`mined detection signal, an extracting circuit responsive
`to the detection signal for extracting message specifying
`information from the pager signal received by the re-
`ceiver, and a message displaying apparatus responsive
`to the message specifying information extracted by the
`extracting circuit for displaying the message specified
`by the message specifying information in a visually
`recognizable manner.
`In the pager terminal apparatus above, the receiver
`receives the pager signal, and the detector detects that
`the pager signal is a signal transmitted to itself and out-
`puts a predetermined detection signal. The extracting
`circuit extracts the message specifying information from
`the pager signal received and supplies the same to the
`message displaying apparatus in response to the detec-
`tion signal. The message displaying apparatus displays
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`5,257,307
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`the message specified by the message specifying infor-
`mation in a visually recognizable manner in response to
`the message specifying information. The pager signal
`employed in accordance with the present
`invention
`includes message specifying information for specifying
`a message along with destination information, which is
`different from the pager signal employed in a conven-
`tional apparatus including destination information and a
`message itself. The message specifying information in-
`cludes a less number of characters compared with the
`body of the message. Therefore, in accordance with the
`pager terminal apparatus,
`the amount of data to be
`transmitted may be reduced. During transmission, the
`message specifying information only may be inputted,
`while the body of the message itself does not need to be
`entered. Therefore,
`the amount of operation by the
`caller may also be reduced. Furthermore, the page sig-
`nal does not include the body of the message, so that
`secret the communication can be accomplished.
`In accordance with another aspect of the invention,
`the radio pager system includes a station for transmit-
`ting a pager signal
`including destination information
`representing the destination and message information to
`be transmitted to the destination, a transmission termi-
`nal apparatus for supplying the destination information
`and the message information to the station, and a pager
`terminal apparatus for presenting a message based on
`the message information included in a received pager
`signal when it receives the pager signal and it deter-
`mines that the received pager signal is destined for itself.
`The pager terminal apparatus includes a receiver for
`receiving an incoming pager signal, a detector for de-
`tecting that the pager signal received by the receiver is
`a signal transmitted to itself and for outputting a prede-
`termined detection signal, an extracting circuit respon-
`sive to the detection signal for extracting message speci-
`fying information for specifying a message, from the
`message information of the pager signal received by the
`receiver, and a message displaying apparatus responsive
`to the message specifying information extracted by the
`extracting circuit for displaying the message specified
`by the message specifying information in a visually
`recognizable manner.
`This radio pager system operates as follows. The -
`45
`caller provides the destination information and the mes-
`sage information to the station, using the transmission
`terminal apparatus. The station transmits via radio a
`pager signal including the destination information and
`the message information provided. The radio-transmit-
`ted pager signal is received by the receiver of the pager
`terminal apparatus. If the detector detects that this
`pager signal is destined for itself, the extracting circuit
`extracts the message specifying information from the
`message information of the pager signal. The message
`displaying circuit displays the message specified by the
`message specifying information in a visually recogniz-
`able manner in response to the extracted message speci-
`fying information. The body of the message need not be
`necessarily included in the pager signal. If the message
`specifying information is included, it is possible to dis-
`play the message to the callee. The caller may provide
`only the message specifying information to the station if
`the correspondence between the message specifying
`information and the messages have been previously
`specified between the caller and the callee and included
`in the message displaying circuit. There is no need to
`provide a long message to the station, nor to transmit
`the body of message from the station. Further scope of
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`applicability of the present invention will become ap-
`parent from the detailed description given hereinafter.
`However,
`it should be understood that the detailed
`description and specific examples, while indicating pre-
`ferred embodiments of the invention, are given by way
`of illustration only, since various changes and modifica-
`tions within the spirit and scope of the invention will
`become apparent to those skilled in the art from this
`detailed description.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other objects, features, aspects
`and advantages of the present invention will become
`more apparent from the following detailed description
`of the present invention when taken in conjunction with
`the accompanying drawings, which are given by way of
`illustration only, and thus are not limitative of the pres-
`ent invention, and wherein:
`FIG. 1 is a typical diagram showing the structure of
`a conventional radio pager system;
`FIG. 2 is a typical diagram showing a communication
`format of a pager signal in a conventional radio pager
`system;
`FIG. 3 is a typical diagram showing the structure of
`a first preferred embodiment of the present invention;
`FIG. 4 is a block diagram of a pager terminal appara-
`tus in accordance with the first preferred embodiment
`of the present invention; and
`FIG. Sis a block diagram of a pager terminal appara-
`tus in accordance with a second preferred embodiment
`of the present invention.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`FIG. 3 is a typical diagram showing the structure of
`a radio pager system in accordance with the preferred
`invention. Referring to FIG. 3, this radio pager system
`includes a so—called electronic pocketbook carried
`about by the caller. A memory card MC may be detach-
`ably provided in the electronic pocketbook M, which
`stores a table including a plurality of paired messages
`predetermined by the caller and the callee and a mes-
`sage code corresponding to it. The table is hereinafter
`referred to as a “message table”. The radio pager system
`further includes a pager base station P capable of being
`connected to a telephone T over a public telephone line
`and an exchange L, a transmitting station S for transmit-
`ting a pager signal supplied from the pager base station
`P, and an electronic pocketbook PT carried about by
`the callee, having a pager receiver for receiving a pager
`signal. The electronic pocketbook PT carried by the
`callee can also be provided detachably with a memory
`card MC in which is stored a message table identical to
`that of the electronic pocketbook M carried about by
`the caller.
`
`The pager system shown in FIG. 3 operates as fol-
`lows. The caller and the callee, as stated above, prepare
`a common message table in advance. Both the caller and
`the callee have memory cards MC in which the message
`tables are stored and which are carried along with the
`electronic pocket books. A table for a calling code
`assigned to each electronic pocketbook is also stored in
`the memory card MC. The caller first obtains a calling
`code of the callee by referring to the calling code table
`stored in the memory card MC using the electronic
`pocketbook M. The caller then chooses the message
`which he intends to transmit to the callee from the
`message table stored in the memory card MC using the V
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`5,257,307
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`electronic pocketbook M. The caller determines the
`message code assigned to the desired message. The
`caller calls the pager base station P over the public
`telephone line and the exchange L, operating the tele-
`phone T. At this time, if the electronic pocketbook M
`has an automatic calling function, the function of the
`electronic pocketbook M may be utilized.
`The pager base station P, like in the conventional
`system, instructs the caller to input a call number of the
`pager terminal and a message code in accordance with
`a predetermined program. The caller, following the
`instruction from the pager base station P, inputs a call
`number of the pager terminal i.e., the electronic pocket-
`book PT carried about by the callee, and a message
`code of a desired message to the pager base station P by
`manipulating the push-buttons of the telephone T. The
`pager base station P transmits via radio the call number
`of the electronic pocketbook PT and the given message
`code in a predetermined format, from the transmitting
`station S.
`
`The pager signal receiver of the electronic pocket-
`book PT receives the pager signal transmitted via radio
`from the transmitting station S of the pager base station,
`and supplies the same to the pager terminal PT. The
`pager terminal PT compares the call number included
`in the received pager signal with the call number as-
`signed to the pager terminal itself. When both of the
`numbers coincide with each other, the electronic pock-
`etbook PT determines that the pager signal is destined
`for it. In that case, the electronic pocketbook PT ex-
`tracts a message code from the pager signal which it
`received. The pager terminal PT further searches the
`message table stored in the memory card MC attached
`to the pager terminal PT with the obtained message
`code as a key. The message having a corresponding
`message code is thereby retrieved from the message
`table. The pager terminal PT displays the retrieved
`message on a display such as a liquid crystal display
`device. Accordingly, the owner of the pager terminal
`PT may readily be aware of the incoming call message
`for him via the pager terminal PT and the contents of
`the message.
`In this system, the information included in the pager
`signal transmitted from the transmitting station S in-
`cludes a call number of the pager terminal PT carried
`about by the callee and a message code for specifying a
`message to be transmitted. In general, a message code is
`represented by much less characters compared with the
`body of the message. The amount of the traffic of the
`signal transmitted from the transmitting station S is by
`far decreased compared with the case in which the
`body of the message is transmitted without using a mes-
`sage code. The caller may transmit a considerably long
`message to the callee simply by searching the message
`table prepared in advance, choosing a desired message,
`and supplying a message code corresponding to the
`message to the pager base station P. It is not necessary
`to operate the telephone T for a long period of time in
`order to input a long message. The message table is
`prepared in the memory card MC, not in the pager base
`station P. Therefore, transmission and reception of a
`necessary and sufficient message between the caller and
`the callee may be effected only by making a common
`message table in advance between the caller and the
`callee and preparing the same in a memory card MC.
`The information transmitted, as stated above is a call
`number and a message code only. The body of the mes-
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`6
`sage is not transmitted, so that secret communication is
`provided.
`FIG. 4 is a block diagram of an embodiment of the
`pager terminal apparatus PT used in the radio pager
`system of the present invention. Referring to FIG. 4,
`this pager terminal apparatus includes a pager signal
`receiver 5 for receiving a pager signal transmitted from
`the transmitting station S, a call number memory 7 for
`in advance a call number assigned to this pager terminal
`apparatus and a call number detector 6 for detecting
`whether the call number stored in the call number mem-
`ory 7 is included in the received pager signal which the
`pager signal receiver 5 supplies. Further included is a
`message code extracting circuit 8 responsive to the call
`number detector detecting that the call number stored
`in the call number memory 7 is included in the pager
`signal for extracting a message code from the received
`pager
`signal,
`standardized sentence code-character
`string converting table 9 for converting the message
`code extracted by the message code extracting circuit 8
`to a predetermined message information, and a display
`10 for displaying character strings representing the
`message supplied from the converting table 9.
`The pager terminal apparatus further includes a con-
`trol circuit 11 for controlling the operations of the call
`number detector 6, the message code extracting circuit
`8, the standardized sentence code-character string con-
`verting table (message table) 9 and the display 10 in
`accordance with a program prepared in advance. Also
`included is a ROM (Read-Only Memory) 13 in which a
`program to be executed by the control circuit 11 is
`stored in advance, a RAM (Random- Access Memory)
`14 which the program uses as a working region, a
`speaker 15 driven by the control circuit 11 for generat-
`ing a beep sound representing that there has been an
`incoming call in the pager terminal from the transmit-
`ting station S, a printer 16 for printing the information
`stored in the RAM 14 and the information of the stan-
`dardized sentence code-character string converting
`table 9, under the control of the control circuit 11, and
`a manually operable keyboard 12 for generating a de-
`sired signal sequence in response to operation by the
`operator and for supplying the same to the control
`circuit 11.
`
`FIG. 2 is typical diagram showing the structure of the
`outline of the communication format used in the radio
`pager system in accordance with the present invention.
`Referring to FIG. 2,
`this communication format in-
`cludes a synchronous signal bit string “SYNC” which is
`a special signal sent for establishing and maintaining a
`fixed relationship in a synchronous system such as one
`between the pager terminal PT and the pager base sta-
`tion P, a calling code “ADDRESS” representing an
`address for specifying a station and so on in the commu-
`nication network, and a message code “MESSAGE
`NO.” for specifying a message transmitted from the
`caller to the callee.
`
`Referring to the Table 1, in the present invention the
`message code and the message are prepared in advance
`in a form such as the message table as shown in Table 1.
`The message code is a 2-digit number, and takes 100
`patterns of 0 to 99. A message as "shown in the right
`section of the Table 1 is assigned to each message code
`in advance. This message converting table is prepared
`by the caller and the callee, converted to data which
`can be electronically processed, and stored in the mem-
`ory card MC.
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`8
`ting station S. and supplies it to the call number detector
`6 and the message code extracting circuit 8.
`The call number detector 6 checks if the call number
`included in the pager signal received coincides with the
`number stored in the call number memory 7. When
`there is one which coincides with the call number
`stored in the call number memory 7 in the pager signal,
`the call number detector 6 supplies a signal to the con-.
`trol circuit 11 indicating the detection of a pager signal
`destined for itself.
`The control circuit 11 causes the message extracting
`circuit 8 to operate in response to the signal applied
`from the call number detector 6. The message extract-
`ing circuit 8 extracts a message code “MESSAGE
`NO.” directly following the call number identical with
`the call number stored in the call number memory 7,
`and supplies it
`to the standardized sentence code-
`character string converting table 9. The standardized
`sentence code-character string converting table 9 re-
`trieves a message corresponding to the message code
`supplied from the message code extracting circuit 8
`from the converting table shown in Table l in accor-
`dance with the instruction of the control circuit 11. The
`retrieved character string is displayed on the display 10.
`The control circuit 11 also drives the speaker 15 in
`response to the signal from the call number detector 6,
`and causes it to generate a beep sound reporting that
`there has been an incoming call. The callee is warned
`that there has been an incoming call by this beep sound,
`and hereinafter inspects the display 10 of the pager
`terminal PT and to read the message displayed thereon.
`In the embodiment above, the standardized sentence
`code-character string converting table 9 is described as
`a memory which is rewritable. The invention, however,
`is not limited to this, and the converting table may be
`prepared in advance in a ROM and the like which can-
`not be rewritten. The standardized sentence code-
`character string converting table 9 need not be stored in
`the memory card MC, and it may be prepared in an
`RAM or an ROM incorporated in the terminal.
`FIG. 5 is a block diagram of another embodiment of
`the pager terminal apparatus used in the radio pager
`system of the present invention. Referring to FIG. 5,
`this pager terminal apparatus includes a pager signal
`receiver 31 for receiving a pager signal transmitted
`from the transmitting station S (FIG. 3) of the pager
`base station P, a call number memory 33 in which the
`call number assigned to this pager terminal is prestored
`a call number detector 32 for detecting if a received call
`number coincides with the call number stored in the call
`number memory 33 in the pager signal received by the
`pager signal receiver 31, a message code extracting
`circuit 34 responsive to the call number detector 32
`detecting that there is included a call number which
`coincides with that stored in the call number memory
`33 in the received pager signal, for extracting a message
`code associated with the call number from the pager
`signal, and an IC card 35 which is a memory card where
`there is stored a message table for converting a message
`code extracted by the circuit 34 to a character string
`representing a message specified by the message code.
`The pager terminal apparatus further includes a dis-
`play 36 including a liquid crystal display device and so
`on for displaying a message obtained by the message
`table of the IC card 35 and a CPU (Central Processing
`Unit) 37 which is control means for controlling the
`operations of the call number detector 32, the message
`code extracting circuit 34, the IC card 35, and the dis-
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`
`
`TABLE 1
`Message Code Message
`#00
`Please give a telephone call to the office
`#01
`Please come back to the oiiice immediately
`#02
`Your client has been here to see you
`
`#99
`
`The radio pager system and the pager terminal appa-
`ratus in accordance with the invention operates as fol-
`lows with reference to FIGS. 2 to 4.
`
`Initialization
`
`When the pager system in accordance with the pres-
`ent invention is used, it is necessary for the caller and
`the callee and change “make” to prepare to make a
`message converting table as shown in Table 1 including
`a plurality of paired message codes and a corresponding
`message. Furthermore, it is necessary to convert the
`message converting table into data which can be elec-
`tronically processed and stored in the standardized
`sentence code-character string converting table 9 of the
`pager terminal PT.
`In order to create this converting table within the
`memory card MC,
`the operator inputs the message
`converting table shown in Table l in the pager terminal
`PT, and has the table stored in the standardized sen-
`tence code-character string converting table 9 in accor-
`dance with the command of the control circuit 11,
`which operates according to the program stored in
`advance in the ROM 13, utilizing the numeric key and
`the alphabetic key (not shown) of the keyboard 12.
`During input, the data inputted is displayed on the dis-
`play 10 for confirmation by the operator.
`The standardized sentence code-character string con-
`verting table 9 needs to be prepared in advance in the
`memory card MC carried about by the caller and the
`memory card MC carried about by the callee. In gen-
`eral, the memory cards MC which store two identical
`data may be obtained by making this converting table in
`either one of the memory cards MC, and then copying
`this converting table in the other.
`
`Operation of Transmission
`
`Suppose that the caller is to transmit a message to a
`person who carries a pager terminal apparatus. The
`caller first, calls the pager base station P over the tele-
`phone T and the exchange L, and then inputs a call
`number of the callee and a message code corresponding
`to the message to be transmitted from the pager base
`station P in accordance with the instruction of the con-
`
`trol corriputer of the pager base station T. The pager
`base station P radio-transmits via radio the inputted call
`number and the message code from the transmitting
`station S in accordance with a communication format
`shown in FIG. 2, as described with respect to Table 1.
`As is apparent from the description above, the data
`transmitted from the transmitting station S does not
`include the body of the message. Even if other person
`should pick up this radio communication, all that he can
`obtain is the call number and the message code only, so
`that the body of the message cannot be obtained.
`
`Operation of Receiving
`
`The pager signal receiver 5 of the pager terminal
`receives the pager signal transmitted from the transmit-
`
`9
`
`

`
`5,257,307
`
`9
`play 36 in accordance with a program prepared in ad-
`vance. Also included is a manually operable keyboard
`39 for generating a desired signal sequence and supply-
`ing it to the CPU 37 in response to the operation of the
`operator, a speaker 41 driven by a speaker driver 45 for
`generating a beep sound corresponding to the signal
`applied from the CPU 37, a ROM 38 where a program
`which the CPU 37 executes is written in advance, an
`RAM 40 which the CPU 37 uses as a working region,
`and a printer 42 controlled by the CPU 37 for printing
`the data stored in the RAM 40 and the IC card 35.
`The pager terminal apparatus further includes a trans-
`mission buffer 43 connected to the CPU 37 for tempo-
`rarily storing a call number of the callee and a message
`code supplied from the CPU 37, a transmission control
`circuit 44 for supplying the transmission data which has
`been temporarily stored in the transmission buffer 43 to
`the speaker driver 45 based on the command given by
`the operator over the keyboard 39, thereby causing the
`speaker 41 to generate a beep sound corresponding to
`the transmission data, and an incoming call signal gener-
`ating circuit 46 connected t