Abstract:
Information on the area occupied by a receiving terminal is present is passed to the sending terminal, prior to setup a call, in units of CAs (Cell Areas) that are smaller than LAs (Local Areas). Accordingly, the position occupied by the sending terminal can be specified, so that calls that are unnecessary due to that position do not have to be made, whereupon unnecessary tolls are avoided.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a mobile communications system, and communications method therein, for setup communications between terminals where at least the terminals on the receiving end are mobile communications terminals (hereinafter “mobile terminals”), and particularly to a mobile communications system and communications method wherein, when there are communications between mobile terminals, notification of the area occupied by a mobile terminal on the receiving end is made to the terminal on the sending end. 
     2. Description of the Related Art 
     FIG. 11 presents an example configuration of a common mobile communications system. In FIG. 11, a situation is presumed wherein a mobile terminal la on the sending end (hereinafter “sending terminal”) performs a call-up request to a mobile terminal  1   b  on the receiving end (hereinafter “receiving terminal”). A call-up request signal from the sending terminal la is routed through a base station  2   a  controlling the area occupied by the sending terminal  1   a , and through a base station controller  3 a controlling a plurality of base stations  2   a , and arrives at a switch  4   a . The area controlled by a base station  2   a  is called a cell area (CA), while an area comprising a plurality of CAs under the control of a base station controller  3   a  is called a location area (LA). The switch  4   a  controls a plurality of base station controllers  3   a.    
     The switch  4   a  accesses an HLR (home location register), finds the switch  4   b  that controls the area occupied by the receiving terminal  1   b , and sends a call-up request signal to the switch  4   b . The HLR is a storage device that stores area information in LA units occupied by mobile terminals. That area information is updated every time any of the mobile terminals move between LAs. 
     Thus the switch  4   a  finds the switch  4   b  controlling the And area occupied by the receiving terminal  1 b, and performs processing to establish communications between the sending terminal  1   a  and the receiving terminal  1   b , following a common ISDN protocol. 
     Conventionally, however, notification of the position occupied by the receiving terminal  1   b  is not made to the sending terminal  1   a  prior to setup the call. Hence a sending party using the sending terminal  1   a  is unable to know beforehand the position of the receiving party using the receiving terminal  1   b . That being so, in cases, for example, where the position occupied by the receiving party is not where the sending party assumes it to be, and there is no need to establish a call, a problem arises in that a call is established, and a toll is paid, even in cases where the position of the receiving party is far removed from the position of the sending party, and where there is no need to communicate at such a high cost. 
     It is also conceivable, on the other hand, that the switch  4   a  will make notification of the LA of the receiving terminal  1   b  obtained from the HLR. However, since an LA is a broad area roughly equivalent to a prefecture, that is too broad an area for determining the position occupied by the receiving terminal  1   b.    
     SUMMARY OF THE INVENTION 
     An object of the present invention, therefore, is to provide a mobile communications system and communications method for notifying a sending terminal, prior to setup a call, of area information capable of specifying the position occupied by the receiving terminal. 
     In order to achieve the object stated above, one aspect of the present invention is that information on the area occupied by a receiving terminal is passed to the sending terminal, prior to setup a call, in units of CAs that are smaller than the LAs described earlier. Accordingly, the position occupied by the sending terminal can be specified, so that calls that are unnecessary due to that position do not have to be made, whereupon unnecessary tolls are avoided. 
     In order to achieve the object stated above, another aspect of the present invention is a mobile communications system comprising: a first switch; a first terminal accommodated in the first switch; a second switch; a plurality of base stations accommodated in the second switch; and a second terminal that is a mobile terminal present inside (occupying) an area controlled by one base station of the plurality of base stations, wherein the second switch acquires information on the area occupied by the second terminal, from a response of the second terminal to a call based on a call establishment request to the second terminal from the first terminal, and sends the area information to the first switch; and the first switch passes the area information to the first terminal during call setup processing. 
     In the invention described above, the first switch determines whether or not the first terminal has display functions. When the first terminal does have display functions, the first switch passes signals for displaying the area information to the first terminal, and when the first terminal does not have display functions, the first switch may pass signals for audio-outputting the area information to the first terminal. 
     In the invention described above, moreover, in a preferable mode thereof, the second switch puts the call setup processing on standby for a prescribed time period following the sending of the area information. 
     At this time, for example, the first switch will send a call release instruction to the second switch when a call disconnect request is received from the first terminal. The second switch will restart call setup processing when no call release instruction is received within the prescribed time period, and will execute call release processing when a call release instruction is received. 
     Alternatively, for example, the first switch will send a call setup processing continuation instruction to the second switch when a call setting processing continuation request is received from the first terminal. The second switch will restart call setup processing when a call setup processing continuation instruction is received from the first switch within the prescribed time period, and will execute call release processing when no call setup processing continuation instruction is received. 
     In the invention described above, furthermore, in another preferable mode thereof, the second switch places call setup processing on standby until a call setup processing continuation instruction is received from the first switch after sending the area information. 
     At this time, for example, the first switch will send a call setup processing continuation instruction to the second switch when no call disconnect request is received from the first terminal, and will send a call release instruction to the second switch when a call disconnect request is received. The second switch will restart call setup processing when a call setup processing continuation instruction has been received from the first switch, and will execute call release processing when a call release instruction has been received from the first switch. 
     Alternatively, for example, the first switch will send a call setup processing continuation instruction to the second switch when a call setup processing continuation request has been received from the first terminal, and will send a call release instruction to the second switch when no call setup processing continuation request has been received. The second switch will restart call setup processing when a call setup processing continuation instruction has been received from the first switch, and will execute call release processing when a call release instruction has been received from the first switch. 
     Furthermore, in order to achieve the object stated above, yet another aspect of the present invention is a method for communicating between a first terminal accommodated in a first switch and a second terminal that is a mobile terminal present inside (occupying) an area controlled by one of a plurality of base stations accommodated in a second switch, comprising the steps of: acquiring information on the area occupied by the second terminal from the response of the second terminal to a call from the second switch based on a call setup request to the second terminal from the first terminal; sending the area information from the second switch to the first switch; and passing the area information from the first switch to the first terminal during call setup processing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A,  1 B and  1 C are diagrams for explaining the theory of the present invention; 
     FIGS. 2A and 2B are diagrams of example configurations of switches configuring a mobile communications system in an embodiment aspect of the present invention; 
     FIG. 3 is a diagram of an example of a conversion table; 
     FIG. 4 is a sequence diagram for a call establishment processing method when continuing call setup processing in a first embodiment aspect of the present invention; 
     FIG. 5 is a sequence diagram for a call establishment processing method when suspending call setup processing in the first embodiment aspect of the present invention; 
     FIG. 6 is a sequence diagram for a call establishment processing method when continuing call setup processing in a second embodiment aspect of the present invention; 
     FIG. 7 is a sequence diagram for a call establishment processing method when suspending call setup processing in the second embodiment aspect of the present invention; 
     FIG. 8 is a sequence diagram for a call establishment processing method when continuing call setup processing in a third embodiment aspect of the present invention; 
     FIG. 9 is a sequence diagram for a call establishment processing method when suspending call setup processing in the third embodiment aspect of the present invention; 
     FIG. 10 is a sequence diagram for a call establishment processing method in a fourth embodiment aspect of the present invention; and 
     FIG. 11 is a configuration diagram of a common mobile communications system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment aspects of the present invention are now described. The technical scope of the present invention, however, is not limited to these embodiment aspects. 
     FIGS. 1A,  1 B, and  1 C are diagrams for explaining the theory of the present invention. FIG. 1A illustrates an example case where a sending terminal  1   a  performs a call-up request to a receiving terminal  1   b . The call-up request, routed through a base station  2   a  that controls the position occupied by the terminal a and through a base station controller  3   a  that controls a plurality of base stations including the base station  2   a , is sent to a receiving-end switch  4   a  that accommodates that base station controller  3   a . The switch  4   a , following signal procedures established by ISUP (ISDN User Part), sends an IAM signal to the receiving-end switch  4   b  accommodating the base station controller  3   b  that controls the position occupied by the receiving terminal  1   b . The switch  4   b , upon receiving the IAM signal, makes a general call-up request to the base station controller  3   b . The base station controller  3   b  sends a general call-up signal to all of the base stations in the area (LA=location area) controlled thereby. Then each of the base stations sends that general call-up signal to the area (CA=cell area) controlled thereby. 
     Now, when the receiving terminal  1   b  occupies the cell area CA controlled by base station  2   b , if the receiving terminal  1   b  receives a general call-up request and sends out a call-up response signal therefor, the call-up response signal from the base station  2   b  is sent via the base station controller  3   b  to the switch  4   b . This call-up response signal contains identification information for the cell area CA controlled by the base station  2   b . The switch  4   b , following the signal procedure established by ISUP, sends out both an ACM signal and an area information signal containing area information corresponding to the CA identification information for the base station  2   b  to the switch  4   a . The switch  4   a , upon receipt of that area information signal, generates either an info signal for displaying the area information for the receiving terminal  1   b  on the display screen of the sending terminal  1   a  or a guidance signal for outputting audio, and sends it via the base station controller  3 a and the base station  2   a  to the sending terminal  1   a.    
     When the sending terminal  1   a  receives the info signal noted above, area information for the receiving terminal  1   b  is displayed on the screen of the sending terminal  1   a  as diagrammed in FIG.  1 B. Or, when it receives the guidance signal noted above, area information from the sending terminal  1   a  is audio-output, as diagrammed in FIG.  1 C. Based on that information, the sending party having the sending terminal  1   a  can choose whether or not to continue processing for connecting to the receiving terminal  1   b.    
     FIGS. 2A, and  2 B are diagrams of example configurations of switches configuring a mobile communications system in an embodiment aspect of the present invention. FIG. 2A is a diagram of an example configuration of the receiving-end switch  4   b , and FIG. 2B is a diagram of an example configuration of the sending-end switch  4   a . In FIG. 2A, the receiving-end switch  4   b  receives a call-up response signal from the receiving terminal  1   b  with a message receiver  401 . Then a CA information extraction unit  402  extracts the CA identification information from the call-up response signal. An area conversion processor  403  references a conversion table  404  and converts the extracted CA identification information to area information. The conversion table  404  is a table containing area information corresponding to the CA identification information for the plurality of base stations controlled by the base station controller. 
     FIG. 3 is a diagram of an example conversion table. In FIG. 3, the conversion table contains area information indexed to CA identification information. For example, in a case where the CA identification information is given by a number, and the CA identification information extracted is CA=10, the 10th area information from the top is selected, for example. 
     A message editing processor  405  edits ISUP-signal messages based on the call-up response signal. In this embodiment aspect of the present invention, the area information is contained in a CHG signal in the ISUP signal. The CHG signal is a message introduced for the purpose of implementing a so-called standard inter-vendor settlement scheme. A standard inter-vendor settlement scheme is a scheme that standardizes interconnections between different vendors, for the purpose of coping with the complexities of mobile-unit communications involving interconnections between a plurality of vendors, by making mutual notifications of vendor information, toll area information, and toll information when the vendor differs between the sending-end switch and the receiving-end switch. The edited ISUP signal (CHG signal containing area information and ACM signal) is sent from an ISUP signal transmitter  406 . is In FIG. 2B, the ISUP signal sent from the ISUP signal transmitter  406  in the receiving-end switch  4   b  is received by an ISUP signal receiver  411  in the sending-end switch  4   a . The ISUP signal receiver  411 , following the ISUP protocol, analyzes the ISUP signal. A subscriber data checking processor  412  examines the subscription conditions of the sending terminal  1   a  subscriber for the service provided by the communications vendor. This checking processor  412  acquires those subscriber conditions from subscriber data in the HLR (home location register; cf. FIG. 1) commonly owned by the mobile communications networks. If the sending terminal  1   a  subscriber is not subscribed to a service (receiving terminal area information notification service) that implements the receiving terminal area information notification method of the present invention, the subscriber data checking processor  412  terminates processing of this service. If the sending terminal  1   a  subscriber is subscribed to this service but the sending terminal  1   a  does not have area information display functions, the subscriber data checking processor  412  passes the area information to a guidance generator connection processor  413 . If the sending terminal  1   a  has area information display functions, the subscriber data checking processor  412  passes the area information to an info signal generating processor  414 . 
     The guidance generator connection processor  413  extracts a guidance control number corresponding to the area information passed to it, from an area information/guidance control number conversion table  415 , and passes that to a guidance generator  416 . The area information/guidance control number conversion table  415  is a table containing guidance (signals for audio output) control numbers corresponding to area information. The guidance generator  416 , which contains pre-loaded guidance data corresponding to the control numbers, sends guidance corresponding to notified control numbers to the sending terminal  1   a  via the base station controller  3   a  and base station  2   a . When that is done, as diagrammed in FIG. 1C, the area information for the receiving terminal  1   b  is audio-output. 
     The info signal generating processor  414 , meanwhile, generates information (info signals) needed to display area information on the display screen of the sending terminal  1   a . The generated info signals are sent from an info signal transmitter  417  via the base station controller  3   a  and base station  2   a  to the sending terminal  1   a . When that is done, as diagrammed in FIG. 1B, area information for the receiving terminal  1   b  is displayed on the display screen of the sending terminal  1   a.    
     Thus, when the area information for the receiving terminal  1   b  is passed to the sending terminal  1   a , in the embodiment aspect of the present invention, time is provided for choosing whether or not to continue call setup processing between the sending terminal  1   a  and receiving terminal  1   b . When continue-processing is instructed by the subscriber within that time, or when nothing is instructed, the sending terminal  1   a  continues call setup processing. When a disconnect instruction is received within that time from the subscriber, the sending terminal  1   a  suspends call setup processing. 
     Hence the sending terminal  1   a  subscriber can obtain area information on where the receiving terminal  1   b  is before setup a call with the receiving terminal  1   b , and can choose, based on that area information, whether or not to establish the call with that receiving terminal  1   b.    
     A concrete description is now given of call setup processing methods in embodiment aspects of the present invention. FIG.  4  and FIG. 5 are sequence diagrams of a call setup processing method in a first embodiment aspect of the present invention. FIG. 4 is a sequence diagram for a case where call setup processing is to be continued. FIG. 5 is a sequence diagram for a case where call setup processing is to be suspended. In the following sequence diagrams, the base stations and base station controllers between the terminals and the switches are omitted, but the signal exchanges between the terminals and the switches are conducted via these entities as described earlier. 
     In FIG. 4, when the sending terminal  1   a  sends a call setup request (SETUP) signal to the switch  4   a , the switch  4   a  sends an address (IAM=initial address message) signal to the switch  4   b . The switch  4   b , upon receipt of the IAM signal, sends an address complete (ACM=address complete) signal to the switch  4   a , and simultaneously sends a general call-up (paging) signal. The receiving terminal  1   b , upon receiving that paging signal, sends a general call-up (paging) response signal to the switch  4   b . When that is done, a base station (not shown) that relays that paging response signal from the receiving terminal  1   b  adds its own CA (cell area) identification information to that paging response signal. 
     The switch  4   b , upon receipt of the paging response signal, sends a CHG signal containing area information to the switch  4   a , as diagrammed in FIG.  2 A. The switch  4   a  that receives that CHG signal, as diagrammed in FIG. 2B, performs subscriber data checking processing, and sends a guidance signal or information signal to the sending terminal  1   a  in accordance with the subscriber conditions. The switch  4   b , upon receiving the CHG signal, activates an internal timer. When a time set in this timer elapses, the setup processing is continued, but when a release instruction (REL=release) signal is received within the set time, call setup processing is suspended. 
     The switch  4   b , after the timer has been activated, executes the authorization and verification processing and radio channel allocation processing that are ordinary call setup procedures. That is, the switch  4   b  sends an authorization request signal to the receiving terminal  1   b , and the receiving terminal  1   b  sends an authorization response signal in response thereto to the switch  4   b . The switch  4   b  also sends a radio channel allocation request signal to the receiving terminal  1   b , and the receiving terminal  1   b  sends a radio channel allocation response signal in response thereto to the switch  4   b.    
     The switch  4   b  does not immediately send the call setup (SETUP) signal upon completion of the authorization and verification processing and radio channel allocation processing, but waits for the time set in the timer to elapse and then sends the call setup (SETUP) signal to the receiving terminal  1   b . The receiving terminal  1   b  that receives the SETUP signal outputs a call-up tone, and sends a calling-up (ALERT) signal to the switch  4   b . The switch  4   b , upon receiving the ALERT signal, sends a call-in-progress (CPG=call progress) signal to the switch  4   a , and the switch  4   a  sends an ALERT signal to the sending terminal  1   a . The switch  4   b , upon receiving a response (CONN=connect) signal from the receiving terminal  1   b , sends a response (ANM) signal to the switch  4   a  and also sends a response acknowledged (CONN ACK=connect acknowledgement) signal to the receiving terminal  1   b . The switch  4   a , upon receiving the response (ANM=answer message) signal, sends a response (CONN) signal to the sending terminal  1   a . Upon receipt thereof, the sending terminal  1   a  sends a response acknowledged (CONN ACK) signal to the switch  4   a . Thus one series of call setup processes is completed, and a call-established state ensues between the sending terminal  1   a  and the receiving terminal  1   b.    
     FIG. 5 is explained next. In FIG. 5, the procedures up to and including the authorization and verification processing and radio channel allocation processing following timer activation by the switch  4   b  are the same as in FIG. 4, and hence are not further described here. When the sending terminal  1   a  subscriber has obtained area information for the receiving terminal  1   b  and judged it unnecessary to continue call setup processing, a disconnect request (DISC=disconnect) signal is sent from the sending terminal  1   a  to the switch  4   a  during the time set in the timer. The switch  4   a  also sends a release instruction (REL=release) signal to the switch  4   b . The switch  4   b , upon receiving the REL signal, performs processing to release the channel established by the radio channel allocation processing noted earlier. That is, the switch  4   b  sends a channel disconnect request signal to the receiving terminal  1   b , and the receiving terminal  1   b  sends a channel disconnect response signal in response thereto to the switch  4   b . The switch  4   b , upon receipt of the channel disconnect response signal, sends a release complete (RLC=release complete) signal to the switch  4   a . Then, upon receipt thereof, the switch  4   a  sends a UA signal to the sending terminal  1   a . Thus call setup processing is suspended, and no call is established between the sending terminal  1   a  and the receiving terminal  1   b.    
     FIG.  6  and FIG. 7 are sequence diagrams of call setup processing in a second embodiment aspect in the present invention. FIG. 6 is a sequence diagram for a case where call setup processing is continued, and FIG. 7 is a sequence diagram for a case where call setup processing is suspended. In FIGS. 6 and 7, unlike in FIGS. 4 and 5, a timer is activated in the switch  4   a . More specifically, in FIGS. 6 and 7, the call setup procedures up until the switch  4   b  sends a CHG signal containing area information to the switch  4   a  are the same as in FIGS. 4 and 5, respectively, and so are not further described here. In FIG.  5  and FIG. 7, the switch  4   a , upon receiving the CHG signal from the switch  4   b , sends either an info signal or guidance signal, according to the subscriber conditions, to the sending terminal  1   a , and also starts an internal timer. This timer terminates, as does the timer in FIGS. 4 and 5, when the prescribed time set has elapsed or when a disconnect request (DISC) signal is received during the set time. 
     In the case where call setup processing is to be continued, in FIG. 6, the switch  4   a , when no disconnect request (DISC) signal has been received within the set time, waits until the time set in the timer has elapsed, and then sends a call setup processing continuation instruction (PRG) to the switch  4   b . The switch  4   b , having received that PRG signal, sends a call setup (SETUP) signal to the receiving terminal  1   b . The call setup procedures following thereupon are the same as in FIG. 4, and so are not further described here. 
     When call setup processing is to be suspended, in FIG. 7, a disconnect request (DISC) signal is sent from the sending terminal  1   a  within the time set in the timer. The call establishment suspension procedures thereafter are the same as in FIG. 5, so are not further described here. Furthermore, although not shown in the diagrams, a PRG signal is also sent from the switch  4   a  to the switch  4   b  in cases where neither an info signal nor a guidance signal is sent. 
     FIG.  8  and FIG. 9 are sequence diagrams for call setup processing in a third embodiment aspect of the present invention. FIG. 8 is a sequence diagram for the case where call setup processing is to be continued and FIG. 9 is a sequence diagram for the case where call setup processing is to be suspended. In this embodiment aspect of the present invention, in FIG.  6  and FIG. 7, the timer in the switch  4   a  is activated. In this embodiment aspect of the present invention, moreover, which is unlike the first and second embodiment aspects described earlier, call setup processing is suspended when the time set in the timer has elapsed, and call setup processing is continued when a call setup processing continuation request (PRG) signal has been received within the set time. 
     Accordingly, in FIG. 8, during the time set in the timer, the switch  4   a , upon receipt of the call setup processing continuation request (PRG) signal from the sending terminal  1   a , sends a call setup processing continuation instruction (PRG) to the switch  4   b  also. The switch  4   b , upon receiving the call setup processing continuation instruction (PRG), sends a SETUP signal to the receiving terminal  1   b  as soon as the authorization and verification processing and radio channel allocation processing described earlier have been completed. Subsequent call setup processing procedures are the same as in FIG. 4, and so are not further described here. 
     In FIG. 9, moreover, when the time set in the timer in the switch  4   a  has elapsed without a call setup processing continuation request (PRG) being received, the switch  4   a  sends a release instruction (REL) to the switch  4   b . The call establishment suspension procedures thereafter are the same as in FIG.  5  and so are not further described here. 
     In FIG.  4  and FIG. 6, furthermore, it is permissible to begin call setup processing by a call setup processing continuation request (PRG) from the sending terminal  1   a  without waiting for the time set in the timer to elapse. In FIG. 9, alternatively, when call setup processing is to be suspended, it is permissible to suspend call setup processing by a disconnect request (DISC) signal from the sending terminal  1   a  without waiting for the time set in the timer to elapse. 
     In FIG.  4  and FIG. 6, moreover, even in cases where the sending terminal  1   a  is not subscribed to the receiving terminal area information notification service, call setup processing will be temporarily suspended until the time set in the timer in either the switch  4   b  (FIG. 4) or  4   a  (FIG. 6) has elapsed, wherefore much time is required to complete the call setup processing. Accordingly, in the case of a sending terminal  1   a  not being subscribed to this notification service, it is permissible that the switch  4   a , upon receipt of a CHG signal, send a call setup processing continuation instruction (PRG) to the switch  4   b . In that way call setup processing will continue without waiting for the time set in the timer to elapse. 
     FIG. 10 is a sequence diagram for a call setup processing method in a fourth embodiment aspect of the present invention. In this embodiment aspect of the present invention, a function is added which enables the receiving terminal  1   b  to refuse to pass its own area information to the sending terminal  1   a . In FIG. 10, the receiving terminal  1   b  sends a special preset number for registering the refusal function to the switch  4   b . When that is done, the switch  4   b  performs an area information notification disabling registration for the receiving terminal  1   b  in the HLR (home location register). The HLR, when that registration is completed, sends a response signal to the switch  4   b . The switch  4   b  then sends a registration verification message as an info signal or guidance signal to the receiving terminal  1   b . Receiving terminals  1   b  that have not been area-information-notification-disable-registered in the HLR are treated as area information notification permitted terminals. Alternatively, the area information notification permission may be registered to the HLR. In those cases, non-registered receiving terminals  1   b  are treated as area information notification disabled terminals. 
     As in FIG. 4, moreover, when the sending terminal  1   a  sends a call setup request (SETUP) signal to the switch  4   a , the switch  4   a  sends an address (IAM=initial address message) signal to the switch  4   b . The switch  4   b , upon receiving the IAM signal, sends an address complete (ACM=address complete) signal to the switch  4   a  and, at the same time, sends a general call-up (paging) signal. The receiving terminal  1   b , upon receiving that paging signal, sends a general call-up (paging) response signal to the switch  4   b . The switch  4   b , upon receiving the paging response signal, accesses the HLR and references the registration respecting area information notification disablement or permission. The switch  4   b , when the receiving terminal  1   b  is an area information notification disabled terminal, sends CHG signal wherein the notification disablement information is added to the area information. The switch  4   a , when notification disabling information is included in the received CHG signal, sends a notification disabled message as an info signal or guidance signal to the sending terminal  1   a . Call setup processing thereafter is the same as in FIG.  4  and so is not further described here. 
     The registration pertaining to area information notification disablement or permission may be effected at the time of subscribing to the communications services of the communications vendor. Alternatively, the configuration may be made so that the registration content can be changed at any time, so that registration may be established or released by transmitting a special number as described earlier. 
     In the embodiment aspects described in the foregoing, the sending terminal  1   a  need not be a mobile terminal; it may instead be a stationary terminal. Also, the signal used in sending area information from the switch  4   b  to the switch  4   a  is not limited to a CHG signal, but may be some other signal (such as an ACM signal, for example), or, alternatively, a signal dedicated to sending area information may be newly established. 
     As based on the present invention, a sending terminal can ascertain the position occupied by a receiving terminal in CA (cell area) units. Accordingly, calls need not be established in cases where, because of the position occupied by the receiving terminal, they are unnecessary, wherefore unnecessary tolls are avoided. 
     The scope wherein the present invention is protected is not limited to the embodiment aspects described in the foregoing, but extends to the inventions described in the claims and their equivalents.