Terminal position managing server, access point, and call control server

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2006-094367, filed on Mar. 30, 2006, the entire contents of which are incorporated herein by reference.

1. Field of the Invention

The present invention relates to a position control server, an access point, and a call control server, and more particularly to a position managing server that manages a position of a mobile terminal in an internet protocol (IP) telephone service, an access point, and a call control server.

2. Description of the Related Art

In recent years, IP telephone services have been prevailing. In a common IP telephone system, IP telephones are fixed terminals similarly to an ordinary wired subscriber telephone service. A call control server that controls calls is usually called “SIP server” because the server utilizes a session initiation protocol.

An SIP server utilizes an SIP uniform resource indicator (SIP-URI) as an identifier of a user. However, the position of a user, that is, the installation site of an IP telephone, can not be identified from the SIP-URI. When position information of an IP telephone needs to be utilized at the time of a call process, a table in which the SIP-URI and the installation site are correlated in a static relation is required. However, because this approach only statically manages the position of the IP telephone, this approach can support the case where the IP telephone does not move, however, this approach can not support the case where the telephone moves.

Wireless IP telephone systems using wireless local area networks (LANs) have started to be used as extension lines in companies. If wireless IP telephone services are offered not only inside the companies but also in public wireless LANs and ordinary houses by communication business entities (carriers), it will be possible for a user to use an IP telephone moving freely among a company, a public wireless LAN, and his/her home.

As a consolidated use of public communication networks and private communication networks, the following communication system is known. The communication system includes a mobile switching system (MSC), a first base station subsystem (BSS) having at least one base station (BTS) that communicates through an air interface using a mobile terminal (MS), and a second subsystem (wireless intranet office (WIO), BTS), that has at least one base transceiver station (BTS) that communicates with the mobile terminal (MS) through an air interface, and is accessible by a first group of mobile communication subscribers of the communication system (for example, Japanese Patent Application Laid-Open Publication No. 2002-507869).

However, as described above, dynamic management of the positions of terminals cannot be achieved in the conventional IP telephone system. Therefore, various problems arise when the service area of the wireless IP telephone service is expanded and when a user moves carrying a terminal. For example, in each of areas such as a company, a public wireless LAN, and home, the maximum number of terminals that can be connected at the same time is limited according to the environment such as a band. However, when a terminal can freely move among those areas, the SIP server can not recognize which area the terminal is making a call from with the SIP-URI, and therefore, it is impossible to limit the number of terminals to be connected at the same time from each of the areas.

When a terminal is connected through a LAN in a company or is connected through a public wireless LAN, the usage fee rate may be varied. However, the SIP server can not recognize the area from which a moving terminal is connected with the SIP-URI, and therefore, the usage fee can not be charged according to the usage fee rate corresponding to the location of the terminal. In addition, even if the terminal that has been connected in one area of one usage fee rate moves to another area of a different usage fee rate, the SIP server can not recognize the destination, and therefore, the usage fee can not be charged according to the location change.

To determine the position of a terminal using the IP address thereof can be contemplated as a means to cope with the location change of a terminal. However, generally, private IP addresses that are available only in the LAN within the company are used in companies. A private IP address is dynamically converted into a global IP address by an application level gateway (ALG) installed in a carrier network of the communication carriers. Therefore, the position of a terminal can not be uniquely identified with the IP address in such environment that private IP addresses are used.

It is an object of the present invention to at least solve the above problems in the conventional technologies.

A position managing server according to one aspect of the present invention manages a position of a mobile terminal wirelessly connected to an access point of a network. The position managing server includes an access point group table in which a plurality of access points are grouped into a plurality of groups each including at least one access point; a terminal position table in which the groups and the mobile terminal are correlated; and a registering unit that registers a current position of the mobile terminal in the terminal position table based on an identifier of the mobile terminal and an identifier of a connected access point that is an access point to which the mobile terminal is connected.

An access point according to another aspect of the present invention relays between a terminal and a network in wireless connection. The access point includes a notifying unit that notifies a server managing a current position of the terminal of a set of an identifier of the access point and an identifier of the terminal being connected to the access point.

A call control server according to still another aspect of the present invention controls connection between a terminal and a network, the terminal wirelessly connected to an access point in the network. The call control server includes an acquiring unit that inquires of a server managing a position of the terminal about the current position of the terminal, and that acquires information on the current position from the server.

The other objects, features, and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings.

FIG. 1 illustrates a wireless IP telephone system using a position managing server, an access point, and a call control server according to embodiments of the present invention;

FIG. 2 illustrates configurations of the position managing server, the access points, an SIP server, a usage fee server, and a terminal;

FIG. 3 illustrates an access point group table;

FIG. 4 illustrates a terminal position table;

FIG. 5 illustrates a terminal position table to which a change of the current position of a terminal T has been made;

FIG. 6 illustrates a simultaneous connection table;

FIG. 7 illustrates a usage fee rate table;

FIG. 8 is a flowchart (Part I) of an initial position registering process;

FIG. 9 is a flowchart (Part II) of the initial position registering process;

FIG. 10 is (Part I) a flowchart of a moving position registering process;

FIG. 11 is (Part II) a flowchart of the moving position registering process;

FIG. 12 is (Part III) a flowchart of the moving position registering process;

FIG. 13 is a flowchart (Part I) of a simultaneous connection control process;

FIG. 14 is a flowchart (Part II) of the simultaneous connection control process;

FIG. 15 is a flowchart (Part I) of a usage fee calculating process; and

FIG. 16 is a flowchart (Part II) of the usage fee calculating process.

Exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 illustrates a wireless IP telephone system using a position managing server, an access point, and a call control server according to embodiments of the present invention. As shown in FIG. 1 , the wireless IP telephone system includes a SIP server 1 that is a call control server, an ALG 2 , a position managing server 3 , a usage fee server 4 , and a carrier network 5 to which a DHCP server (not shown), an authenticating server (not shown), etc., are installed.

The wireless IP telephone system includes user networks such as a company network 7 a to which one or more access points (APs) 6 a , 6 b , 6 c , and 6 d are installed and a home 7 b , a public wireless LAN 7 c of a communication carriers, to which one or more access points (APs) 6 e , 6 f , and 6 g are installed, and a terminal 8 that can move freely among the company network 7 a , the home 7 b , and the public wireless LAN 7 c . The reason why three terminals 8 are depicted in FIG. 1 is to show that the terminal 8 can move between the company network 7 a , the home 7 b , and the public wireless LAN 7 c.

The terminal 8 has a wireless LAN function according to IEEE802.11a/b/g, etc., and communicates with the networks by connecting to the access points 6 a to 6 g . The access points 6 a to 6 g offer communication with the networks to the terminal 8 connected by wireless. Each of the access points 6 a to 6 g notifies the position managing server 3 of information to identify the terminal 8 being connected.

The access points 6 a to 6 g are grouped and managed as an access point group. The unit of the group can be arbitrary set as the company network 7 a for the whole company or for each base, the home 7 b , or the public wireless LAN 7 c . Generally, in the company network 7 a or the home 7 b , a private IP address is given to each of the access points 6 a to 6 h . In the public wireless LAN 7 c , a global IP address is given or a private IP address is given to each of the access points 6 a to 6 g . In the embodiment, either of a global IP address or a private IP address may be given to each of the access points 6 a to 6 g.

The ALG 2 converts IP addresses and ports of IP packets transmitted and received among the company network 7 a , the home 7 b , or the public wireless LAN 7 c , etc., and the communication carrier network 5 and exchanges information in SIP messages. When a private IP address is given to each of the terminal 8 and the access points 6 a to 6 g , the ALG 2 converts a private IP address into a global IP address. Thereby, communication is enabled among each of the terminal 8 and the access points 6 a to 6 g each being given a private IP address, and each apparatus in the carrier network each being given a global IP address.

The SIP server 1 executes session control based on the SIP protocol. The SIP server 1 inquires of the position managing server 3 about the position of the terminal 8 and receives a response to the inquiry from the position managing server 3 . The SIP server 1 notifies the usage fee server 4 of usage fee information of the terminal 8 . The usage fee server 4 calculates the fee to be charged to the user of the terminal 8 based on the usage fee information notified of from the SIP server 1 .

The position managing server 3 manages which group each of the access points 6 a to 6 g belongs to and which access point the terminal 8 is currently being connected to. The position managing server 3 receives the information on the terminal 8 being connected that is notified of from each of the access points 6 a to 6 g . The position managing server 3 responds to the inquiry from the SIP server 1 about the position of the terminal 8 .

FIG. 2 illustrates configurations of the position managing server, the access points, the SIP server, the usage fee server, and the terminal. As shown in FIG. 2 , the terminal 8 includes a terminal information notifying unit 81 that notifies an access point of the connection destination of the identifier of the terminal 8 . The SIP-URI of the terminal 8 is used as the identifier of the terminal 8 . Otherwise, a global IP address may be used as the identifier of the terminal 8 when each of all the terminals 8 has a global IP address.

Though not especially limited, it is assumed that a first access point group (# 1 ) 7 d and a second access point group (# 2 ) 7 e are set as the access point groups, and that a first access point (# 1 ) 6 b , a second access point (# 2 ) 6 j , and a third access point (# 3 ) 6 k belong to the first access point group 7 d , and a fourth access point (# 4 ) 6 m , a fifth access point (# 5 ) 6 n , and a sixth access point (# 6 ) 6 p belong to the second access point group (# 2 ) 7 e.

The first access point 6 h includes a terminal information acquiring unit 61 and an identification information notifying unit 62 . The terminal information acquiring unit 61 receives the identifier of the terminal 8 from the terminal 8 being connected to. The identification information notifying unit 62 notifies the position managing server 3 of the identifier of the terminal 8 itself and a combination of the identifiers of the terminals 8 being connected to that is acquired from the terminal information acquiring unit 61 , using simple network management protocol (SNMP), SIP, etc. The identification information notifying unit 62 may use another communication protocol. The configuration and the operation of each of the second to the sixth access points 6 j to 6 p are same as those of the first access point 6 h , and therefore, the description thereof is omitted.

As the identifier of each of the access points 6 h to 6 p , an identifier with which each of the access points 6 h to 6 p can be uniquely identified among communication carriers is used. For example, a basic service set identification (BSSID) or a name specific to an access point is used. Otherwise, a global IP address may be used as the identifier of each of the access points 6 h to 6 p when a global IP address is given to each of all the access points 6 h to 6 p.

The position managing server 3 includes an identification information acquiring unit 31 , an access point group table 32 , a terminal position table 33 , a position information registering unit 34 , a position information changing unit 35 , a position information notifying unit 36 , and a connection information notifying unit 37 . The identification information acquiring unit 31 receives the identifier of each of the access points 6 h to 6 p and a combination of the identifiers of the terminals 8 being connected to each of the access points 6 h to 6 p , from each of the access points 6 h to 6 p.

The access point group table 32 is a database that manages the correlation between the access point groups 7 d and 7 e , and access points 6 h , 6 j , 6 k , 6 m , 6 n , and 6 p that belong to the groups. FIG. 3 illustrates the access point group table. A name uniquely identifiable among communication carriers is given to each of access point groups 7 d and 7 e.

As one example in this case, it is assumed that the names of the first access point group 7 d and the second access point group 7 e are respectively G# 1 and G# 2 , and that the identifiers of the first, the second, the third, the fourth, the fifth, and the sixth access points 6 h , 6 j , 6 k , 6 m , 6 n , and 6 p are respectively AP# 1 , AP# 2 , AP# 3 , AP# 4 , AP# 5 , and AP# 6 .

The terminal position table 33 is a database that manages the correlation between the names of the access point groups 7 d and 7 e , and the terminal 8 being connected to the access point group 7 d or 7 e . The position information registering unit 34 registers the identifier of the terminal 8 in the column for “access point group that the access point of the connection destination belongs to” in the terminal position table 33 based on the identifiers of the access points 6 h to 6 p acquired from the access points 6 h to 6 p and the combination of the identifiers of the terminals 8 being connected to access points 6 h to 6 p.

FIG. 4 illustrates the terminal position table. In FIG. 4 , the case is shown in which a terminal T is connected to an access point that belongs to the first access point group 7 d and no terminal is connected to any access point that belongs to the second access point group 7 e , as an example. In the column for “terminal” of the terminal position table 33 , a SIP-URI that is an identifier of a terminal is registered, however, “terminal T” is represented herein for simplicity.

When the position of the terminal 8 registered in the terminal position table 33 is different from the current position of the terminal 8 , the position information changing unit 35 changes the position of the terminal 8 registered in the terminal position table 33 to the current position. For example, it is assumed that the terminal T has connected to an access point belonging to the first access point group 7 d at the previous time and, therefore, the identifier of the terminal T is registered in the column for the first access point group 7 d in the terminal position table 33 (see FIG. 4 ).

In this state, when the terminal T is connected to an access point belonging to the second access point group 7 e , the position information changing unit 35 deletes the identifier of the terminal T from the column for the first access point group 7 d in the terminal position table 33 and registers the identifier of the terminal T in the column for the second access point group 7 e . FIG. 5 depicts the terminal position table to which the change of the current position of the terminal T has been made.

When the current position of the terminal 8 is inquired about from the SIP server 1 , the position information notifying unit 36 , in response to the inquiry, refers to the terminal position table 33 and notifies the SIP server 1 of the access point group to which the terminal 8 is connected (in the example of FIG. 4 , the first access point group 7 d ). When the terminal 8 has changed the connection destination thereof, for example, from an access point belonging to the first access point group 7 d to an access point belonging to the second access point group 7 e during one connection, the connection information notifying unit 37 notifies the SIP server 1 of the second access point group 7 e after the change and the time of the day of the change.

The SIP server 1 includes a position information acquiring unit 11 , a simultaneous connection control table 12 , a connection control unit 13 , a connection information recording unit 14 , and a usage fee information notifying unit 15 . The position information acquiring unit 11 inquires of the position managing server 3 about the current position of the terminal 8 , and as a response to the inquiry, acquires from the position managing server 3 the information on the access point group to which the access point connected to the terminal 8 belongs (in the example of FIG. 4 , the first access point group 7 d ).

The simultaneous connection control table 12 stores the number of terminals that can be connected at the same time to each of the access point groups 7 d and 7 e , and the number of terminals actually connected thereto, for each of the access point groups 7 d and 7 e . FIG. 6 depicts an example of the simultaneous connection number managing table. FIG. 6 depicts an example that is the case where the simultaneous connectable number (the contracted number) of the first access point group 7 d is 10 and the total of the number of terminals that are actually connected to the access points 6 h , 6 j , and 6 k of the first access point group 7 d is five and the simultaneous connectable number (the contracted number) of the second access point group 7 e is 15 and the number of terminals that are actually connected to the access points 6 m , 6 n , and 6 p of the second access point group 7 e is 0.

When a call making request is issued from the terminal 8 , the connection control unit 13 acquires from the position managing server 3 information on the access point group to which the access point of the connection destination of the terminal 8 belongs. The connection control unit 13 refers to the simultaneous connection control table 12 and, when the number of actual connections of the access point group is less than the simultaneous connectable number, accepts the call making request and continues the call process. When the number of actual connections is equal to the simultaneous connectable number, the connection control unit 13 stops the call process.

The connection information recording unit 14 records as connection information the starting time of the call process in response to the call-making request of the terminal 8 and the name of the access point group that the access point at that time of the connection destination belongs to; when an access point belonging to a different access point group is connected during the connection, the name of the access point group of the new connection destination acquired from the position information notifying unit 36 of the position managing server 3 and the time of the change; and the ending time of the series of call process steps. The usage fee information notifying unit 15 notifies the usage fee server 4 of the connection information recorded by the connection information recording unit 14 as usage fee information.

The usage fee server 4 includes a usage fee table 41 . The usage fee table 41 is a database that manages the correlation between the access point groups 7 d and 7 e and usage fee rates. FIG. 7 depicts an example of the usage fee table. FIG. 7 depicts an example that is the case where the usage fee rate of the first access point group 7 d is 10 yen per three minutes and the usage fee rate of the second access point group 7 e is eight yen per three minutes. The configurations and the operations thereof that realize the functions other than the position administration of the terminal 8 such as a transmitting process, a receiving process, a confidentiality process of data are omitted as to the SIP server 1 , the ALG 2 , the access points 6 h , 6 j , 6 k , 6 m , 6 n , and 6 p , and the terminal 8 .

Description will be given for the operation executed when the terminal 8 (hereinafter, “terminal T 8 ”) is connected to the first access point 6 h of the first access point group 7 d . In this case, it is assumed that the information of the terminal T 8 is not registered in the position managing server 3 because the terminal T 8 is connected to any one access point for the first time, or a specific time period has passed since the terminal T 8 was connected to the access point at the previous time and, therefore, the registered information of the terminal T 8 has been deleted from the position managing server 3 . Therefore, a process to register the initial position of the terminal T 8 is executed caused by the connection of the terminal T 8 .

FIGS. 8 and 9 are flowcharts of an initial position registering process. Processes shown in FIG. 9 are continued from that shown in FIG. 8 . As shown in FIG. 8 , the terminal T 8 starts a wireless connection to the first access point 6 h (step A 1 ). When the connection is established (step A 2 : YES), the terminal T 8 starts registration to the SIP server 1 using a SIP REGISTER (step A 3 ). When the registration has been completed (step A 4 : YES), the first access point 6 h reads the SIP-URI of the terminal T 8 from the SIP REGISTER (step A 5 ).

When the terminal T 8 can not be connected to the first access point 6 h (step A 2 : NO) or when the terminal T 8 is not registered in the SIP server 1 (step A 4 : NO), an error process is executed and the initial position registering process is ended. Following step A 5 , as shown in FIG. 9 , the first access point 6 h notifies the position managing server 3 of the SIP-URI of the terminal T 8 and the identifier of the first access point 6 h itself as position information (step A 6 ).

The position managing server 3 searches the access point group table 32 using the identifier of the first access point 6 h as a key of the information received from the first access point 6 h and retrieves the access point group that the first access point 6 h belongs to (step A 7 ). When the retrieval can not be completed (step A 8 : NO), an error process is executed and the initial position registering process is ended. When the retrieval is completed (step A 8 : YES), the first access point 6 h turns out to belong to the first access point group 7 d and, therefore, the position managing server 3 searches the terminal position table 33 using the identifier (the SIP-URI) of the terminal T 8 as a key and retrieves the presence or absence of an entry of the terminal T 8 (step A 9 ).

As a result, when the entry of the terminal T 8 can be retrieved (step A 10 : YES), the initial position registering process is ended. When no entry of the terminal T 8 is found (step A 10 : NO), the identifier of the terminal T 8 is added into the column for “terminal” corresponding to the first access point group 7 d of the terminal position table 33 (step A 11 ), and the series of initial position registering process steps are ended.

Description will be given for the case where the terminal T 8 moves after the terminal TB has been connected to an access point belonging to the first access point group 7 d , is located in the area of the second access point group 7 e , and is connected to the fourth access point 6 m . In this case, it is assumed that the identifier of the terminal T 8 is registered in the column for “terminal” corresponding to the first access point group 7 d of the terminal position table 33 . Therefore, a process to register the position of the terminal T 8 during the move thereof is executed caused by the connection of the terminal T 8 to the fourth access point 6 m after the move thereof.

FIGS. 10 to 12 are flowcharts of a moving position registering process. Processes shown in FIGS. 11 and 12 are respectively continued portions of FIGS. 10 and 11 . As shown in FIG. 10 , the terminal T 8 starts a wireless connection to the fourth access point 6 m (step B 1 ). When the connection has been established (step B 2 : YES), the terminal T 8 starts registration thereof to the SIP server 1 using the SIP REGISTER (step B 3 ). When the registration has been completed (step B 4 : YES), the fourth access point 6 m reads the SIP-URI of the terminal TB from the SIP REGISTER (step B 5 ).

When the terminal T 8 can not be connected to the fourth access point 6 m (step B 2 : NO) or when the terminal T 8 is not registered in the SIP server 1 (step B 4 : NO), an error process is executed and the moving position registering process is ended. Following step B 5 , as shown in FIG. 11 , the fourth access point 6 m notifies the position managing server 3 of the SIP-URI of the terminal T 8 and the identifier of the fourth access point 6 m itself as position information of the terminal T 8 (step B 6 ).

The position managing server 3 searches the access point group table 32 using the identifier of the fourth access point 6 m as a key of the information received from the fourth access point 6 m and retrieves the access point group to which the fourth access point 6 m belongs (step B 7 ). When the retrieval can not be completed (step B 8 : NO), an error process is executed and the moving position registering process is ended. When the retrieval is successfully completed (step B 8 : YES), the fourth access point 6 m turns out to belong to the second access point group 7 e and, therefore, the position managing server 3 searches the terminal position table 33 using the identifier (the SIP-URI) of the terminal T 8 as a key and retrieves the presence or absence of an entry of the terminal T 8 (step B 9 ).

When no entry of the terminal T 8 is found (step B 10 : NO), an initial registering process is executed that adds the identifier of the terminal T 8 into the column for “terminal” corresponding to the second access point group 7 e of the terminal position table 33 (step B 11 ). When the entry of the terminal T 8 can be retrieved (step B 10 : YES), the terminal T 8 is turned out to be registered in the column for “terminal” corresponding to the first access point group 7 d.

As shown in FIG. 12 , the name of the access point group (G# 1 ) turned out by searching the access point group table 32 at step B 7 is compared with the name of the access point group (G# 2 ) turned out by searching the terminal position table 33 at step B 9 (step B 12 ). When both group names match (step B 13 : YES), the moving position registering process is ended.

When the group names do not match (step B 13 : NO), the identifier of the terminal T 8 registered in the column for “terminal” corresponding to the first access point group 7 d of the terminal position table 33 is deleted. The identifier of the terminal T 8 is added to the column for “terminal” corresponding to the second access point group 7 e of the terminal position table 33 . Such updating of the terminal position table 33 is executed (step B 14 ) and the series of moving position registering process steps are ended.

By executing the moving position registering process, the position managing server 3 can manage at real time the information on the access point group to which the terminal T 8 belongs. The moving position registering process can cope with both of the case where the terminal T 8 moves during one connection and is located in the areas of a plurality of access point groups and the case where the terminal T 8 makes a call in the area of an access point group that is different from that of the previous time.

Description will be given for a process that limits the number of terminals connected at the same time for each access point group. It is assumed that the correlation between the access point groups and the terminal T 8 is known due to the above initial position registering process and the moving position registering process. When the terminal T 8 issues a call making request, the process that limits the number of simultaneously connected terminals is executed.

FIGS. 13 and 14 depict a flowchart of the simultaneous connection control process and FIG. 14 is a continued portion of FIG. 13 . As shown in FIG. 13 , when the terminal T 8 issues a call making request to the SIP server 1 using SIP INVITE (step C 1 ), the SIP server 1 inquires of the position managing server 3 which access point group the terminal T 8 is located in (step C 2 ). In response to the inquiry from the SIP server 1 , the position managing server 3 responds with the name of the access point group in which the terminal T 8 is located (step C 3 ).

The SIP server 1 refers to the simultaneous connection control table 12 and compares the number of current actual connections with the number of simultaneously connectable terminals (the contracted number) for the access point group responded with from the position managing server 3 (step C 4 ). As a result, when the number of current actual connections is equal to the number of simultaneously connectable terminals (the contracted number) (step C 5 : YES), the SIP server 1 discontinues the call process and responds to the terminal T 8 that the SIP server 1 is busy (step C 6 ) and the series of simultaneous connection control process steps are ended, as shown in FIG. 14 .

When the number of current actual connections is not equal to the number of simultaneously connectable terminals (the contracted number) (step C 5 : NO), the number of current actual connections is less than the number of simultaneously connectable terminals (the contracted number). Therefore, as shown in FIG. 14 , the SIP server 1 adds one to the value in the column for “number of current actual connections” corresponding to the access point group concerned in the simultaneous connection control table 12 (step C 7 ). The SIP server 1 continues a call connecting process (step C 8 ) and the series of simultaneous connection control process steps are ended. By executing the simultaneous connection control process, for example, a service can be executed that limits the number of terminals actually connected simultaneously to a number less than the contracted number for each base by setting the number of simultaneously connected terminals for each base in a company.

Description will be given for a process to charge the fee at a usage fee rate that differs depending on each access point group when a usage fee rate is set for each access point group and the terminal T 8 moves among the areas of access point groups each having a usage fee rate different from each other during one connection thereof. It is assumed that the correlation between the access point groups and the terminal T 8 is known due to the above initial position registering process and the moving position registering process. When the terminal T 8 issues a call making request, a usage fee calculating process is executed.

FIGS. 15 and 16 depict a flowchart of the usage fee calculating process and FIG. 16 is a continued portion of FIG. 15 . As shown in FIG. 15 , when the terminal T 8 issues a call making request to the SIP server 1 using SIP INVITE (step D 1 ), the SIP server 1 inquires of the position managing server 3 which access point group the terminal T 8 is located in (step D 2 ).

In response to the inquiry from the SIP server 1 , the position managing server 3 responds with the name of the access point group in which the terminal 8 is located (step D 3 ). In this case, it is assumed that the terminal T 8 is connected to the first access point 6 h and “G# 1 ” that is the name of the first access point group 7 d is responded with from the position managing server 3 to the SIP server 1 . The SIP server 1 connects the call (step D 4 ), starts recording of usage fee information, and records the starting time of the call process and the name of the connection destination access point group (step D 5 ).

When the terminal T 8 moves during the connection and, as a result, the connection destination is changed from the first access point 6 h to the fourth access point 6 m (step D 6 ), the above moving position registering process is executed and the terminal position table 33 is updated (step D 7 ). As shown in FIG. 16 , the position managing server 3 notifies the SIP server 1 of the name of the access point group including an access point that is the new connection destination of the terminal T 8 and the time at which the connection destination is changed as terminal move information (step D 8 ). In this case, G# 2 is responded with that is the name of the second access point group 7 e from the position managing server 3 to the SIP server 1 .

The SIP server 1 records the information received from the position managing server 3 as usage fee information (step D 9 ). When the call is ended, the SIP server 1 ends the call process (step D 10 ), records the ending time, and ends the recording of the usage fee information (step D 11 ). The SIP server 1 transmits the usage fee information recorded therein to the usage fee server 4 (step D 12 ).

The transmitted usage fee information includes the call starting time, the call ending time, and the name of the access point group including the access point of the connection destination. When the connection destination of the terminal T 8 is changed to another access point belonging to a different access point group during one connection, the name of the access point group to which the access point of the new connection destination and the time of the change are also transmitted as usage fee information. Not limiting to the above pieces of information, the usage fee information is updated as necessary, according to the difference in the usage fee calculating scheme.

The usage fee server 4 refers to the usage fee table 41 and calculates the fee corresponding to the rate of each access point group based on the usage fee information received from the SIP server 1 (step D 13 ) and ends the series of usage fee calculating process steps. By executing the usage fee calculating process, fee charging corresponding to the transmission area of a user is enabled. For example, it is possible to vary the usage fee rate between the case where the user transmits from the public wireless LAN 7 c and the case where the user transmits from the home 7 b.

As described above, according the embodiment, the identifier of the terminal 8 and the identifier of the first access point 6 h that the terminal 8 is being connected to are notified of from the first access point 6 h to the position managing server 3 and, based on the notified combination of the identifiers, the position managing server 3 manages the correlation between the access points and the access point groups and the correlation between the access point groups and the terminal 8 using the access point group table 32 and the terminal position table 33 . Therefore, the location of the terminal 8 that is moving can be dynamically managed. Thereby, a subscriber can receive seamlessly the wireless IP telephone service from the communication carriers without noticing his/her location in a company, a public wireless LAN, or a home.

By managing the actual connection number and the contracted number of terminals using the simultaneous connection control table 12 , the number of simultaneous connections of the terminals can be limited for each access point group. By setting a usage fee rate for each access point group using the usage fee table 41 , the fee can be charged at usage fee rates that are different respectively for the access point groups.

The maximum number of simultaneously connectable terminals can be dynamically varied corresponding to the number of users in an access point group. A user can be restrained from transmitting from an access point group, that is, a network. The usage fee rate can be varied according to the number of users in an access point group.

Because a communication carrier can grasp at real time the location of a subscriber, the communication carrier can offer a new service utilizing the position information of the subscriber such as a service of sending information of the area, corresponding to the area of the access point group in which the terminal is located. Corresponding to the area of the access point group that the terminal is located in, the communication carriers can also limit the networks, services, etc., that the terminal can access and offer a service that changes the transfer destination of a call, etc.

According to the embodiments described above, dynamic management of the position of a moving terminal can be realized. Moreover, the number of simultaneously-connected terminals can be limited for each area. Furthermore, the usage fee can be calculated at usage fee rates depending on the area.

Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.