disclosed herein are a mechanism and method to easily register a mobile station at csg ( closed subscriber group ) of hnb ( home node b ) that restricts access so that only a mobile station registered in advance is permitted to access the csg . embodiments of the present invention are described in detail with reference to the accompanying drawings . fig1 is a block diagram illustrating a configuration of a mobile communication system of the present invention . as illustrated in fig1 , a user 10 can operate a mobile station 20 , and can also operate an hnb 30 in the installation facility of the hnb 30 . the mobile station 20 and the hnb 30 can transmit and receive radio signals therebetween . a home subscriber server ( hereinafter referred to as hss ) 40 is a database that manages subscriber information in the mobile communication system . the hss 40 manages a list of csg which can access the hnb 30 . the hnb 30 of the present invention includes a button 31 that is operated by the user 10 and a lamp 32 that is used by the user 10 to confirm displaying . however , these elements are illustrated for exemplary purposes only . as long as the button 31 has a function of receiving an instruction in any form from the user 10 and the lamp 32 has a function of displaying any status to the user 10 , these elements satisfy the spirit of the present invention . in order to register a mobile station 20 that has not been registered at the csg yet , a user first operates the button 31 of the hnb 30 to set the hnb 30 to a particular operation mode to register the mobile station 20 . the hnb 30 normally receives no access from the mobile station 20 that has not been registered as a csg , but in this operation mode , the hnb 30 receives a call at a special telephone number corresponding to a registration function in the hnb 30 . upon receiving the call at the special telephone number predetermined at the particular operation mode for registration of the mobile station 20 , the hnb 30 extracts , from the access , mobile station information including a mobile station id of the mobile station 20 and registers at the hss 40 the mobile station information together with base station information . fig2 is a sequence chart illustrating a procedure example to register a mobile station 20 at hss 40 in accordance with a first embodiment of the present invention . in order to register at the hnb 30 the mobile station 20 that has not been registered yet at the csg , the user 10 first operates the button 31 of the hnb 30 and configures the hnb 30 to be in the particular operation mode for registration of the mobile station 20 ( step s 101 ). the hnb 30 normally receives no access from the mobile station 20 that has not been registered as a csg , but in this operation mode , the hnb 30 receives the call at the special telephone number prepared for the registration function . in order to indicate that the hnb 30 enters this mode , the hnb 30 lights the lamp 32 , thereby displaying the particular mode to the user 10 ( step s 103 ). note that the particular operation mode may time out if a call to be discussed later is not received within a constant period of time , and that the hnb 30 may resume a standard operation status . upon confirming lamp lighting ( step s 103 ) occurring in response to a button operation ( step s 101 ), the user 10 performs a call operation ( step s 105 ) at a specific telephone number predetermined by the mobile station 20 . the specific telephone number predetermined is simply different from a telephone number for ordinary communication . any telephone number may be designated by the hnb 30 , but “# 11 ” may be set herein for discussion . upon receiving the call operation ( step s 105 ) on the specific telephone number , the mobile station 20 places a call to the hnb 30 ( step s 107 ). it is contemplated that the call of the call operation ( step s 105 ) includes as a key an id unique to the hnb 30 written on the housing of the hnb 30 or an accompanying manual of the hnb 30 . upon receiving the call ( step s 107 ) at the specific telephone number predetermined in the particular mode for the registration of the mobile station 20 , the hnb 30 extracts from the access the mobile station information including the mobile station id of the mobile station 20 ( step s 109 ). the hnb 30 also prepares base station information including a base station id and the like of the hnb 30 itself ( step s 111 ), constructs registration information addressed to the hss 40 by combining the base station information with the mobile station information ( step s 113 ), and registers the registration information ( step s 115 ). upon completing this series of operations , the hnb 30 shifts to the standard mode and extinguishes the lamp 32 . upon receiving the registration information , the hss 40 updates a subscriber information database therewithin to add thereto the mobile station 20 having the mobile station id given in a csg list of the hnb 30 of a given base station id . the hnb 30 references the subscriber information database and receives an access from the mobile station 20 after the subscriber information database is updated . in the first embodiment , the hnb 30 includes the button 31 to cancel the access restriction when the mobile station 20 accesses for registration . in order to newly register the mobile station 20 , the call is placed at the specific telephone number corresponding to the registration function of the hnb 30 with the access restriction canceled by the function of the button 31 . the mobile station 20 having made the call operation is thus added to the list of the mobile stations 20 that are permitted to access the hnb 30 on the hss 40 within a network . since the hss 40 is then provided with information including the id of the calling mobile station 20 and the base station id of the hnb 30 through which the call has passed , the user 10 is free from the necessity of setting these pieces of information . since the button 31 that is arranged on the housing of the hnb 30 needs to be controlled in accordance with the procedure , the user is free from performing the security setting using a password or the like in the registration of the mobile station 20 . as a result , user friendliness is increased . in accordance with the first embodiment , the user 10 performs the button operation on the hnb 30 to set the hnb 30 to be in the particular operation mode for the registration of the mobile station 20 . the registration of the mobile station 20 at the csg is thus facilitated . in accordance with a second embodiment , the button operation by the user 10 on the hnb 30 is interpreted as authentication for the registration operation . more specifically , the function of the button 31 on the hnb 30 of fig1 is different from the function of the button 31 in the first embodiment . fig3 is a sequence chart illustrating a procedure example to register the mobile station 20 at the hss 40 in accordance with the second embodiment of the present invention ( an example with a button operation for registration verification ). the user 10 performs a call operation on the hnb 30 at a specific telephone number predetermined first by the mobile station 20 ( step s 201 ). the hnb 30 is a csg cell and does not receive a standard access from the mobile station 20 , but usually receive an access at the specific telephone number . it is contemplated that the call of the call operation ( step s 201 ) includes as a key an id unique to the hnb 30 written on the housing of the hnb 30 or an accompanying manual of the hnb 30 . in response to the reception of the call ( step s 203 ), the hnb 30 lights the lamp 32 to prompt the user 10 to perform the button operation ( step s 205 ) and thus causes the user 10 to verify that the user 10 accepts the registration of the mobile station 20 . the hnb 30 also extracts from the access from the mobile station 20 the mobile station information including the mobile station id of the mobile station 20 ( step s 207 ). the hnb 30 prepares the base station information including the base station id of the hnb 30 itself ( step s 209 ), and thus constructs the registration information addressed to the hss 40 by combining the base station information and the mobile station information ( step s 211 ). in order to verify the registration of the mobile station 20 , the user 10 performs the button operation ( step s 213 ). if no button operation is performed within a constant period of time ( step s 213 ), and the verification of the registration of the mobile station 20 by the user 10 is not confirmed , the hnb 30 may time out in a verification period , quit the registration , and resume a standard operation status . subsequent to the button operation by the user 10 ( step s 213 ), the hnb 30 registers the registration information on the hss 40 ( step s 215 ). upon completing this series of operations , the hnb 30 shifts to the standard mode and extinguishes the lamp 32 . in accordance with the second embodiment , the button operation performed by the user 10 on the hnb 30 is interpreted as verification of the registration operation . in this way , the registration verification necessitates the user &# 39 ; s controlling the button 31 arranged on the housing of the hnb 30 and the user 10 is freed from performing the security setting using the password or the like in the registration of the mobile station 20 . as a result , user friendliness to the user 10 is increased . security seems to be sufficiently ensured in the first and second embodiments by taking steps including operating the button 31 or the like arranged on the hnb 30 in a building having the hnb 30 installed therewithin . furthermore , it is also contemplated that additional verification steps include a step of transmitting a mail , a voice communication , or the other means to the management subscriber 50 associated with the hnb 30 to verify whether to accept the registration . more specifically , the functions of the button 31 , the lamp 32 and the like in a third embodiment are substantially identical to those of the second embodiment . fig4 is a sequence chart illustrating a procedure example to register the mobile station 20 at the hss 40 in accordance with the third embodiment of the present invention ( an example inclusive of a verification procedure of the management subscriber 50 ). fig4 illustrates an example in which an additional step by the management subscriber 50 is included in the second embodiment . the user 10 performs a call operation to the hnb 30 at a specific telephone number predetermined by the mobile station 20 ( step s 301 ). upon receiving the call ( step s 303 ), the hnb 30 lights the lamp 32 to prompt the user 10 to perform the button operation in order to verify whether the user 10 accepts the registration of the mobile station 20 ( step s 305 ). the hnb 30 also extracts from the access from the mobile station 20 the mobile station information including the mobile station id of the mobile station 20 ( step s 307 ), prepares the base station information including the base station id of the hnb 30 itself ( step s 309 ), and constructs the registration information addressed to the hss 40 by combining the base station information with the mobile station information ( step s 311 ). in order to verify the registration of the mobile station 20 , the user 10 performs the button operation ( step s 313 ). if no button operation is performed within a constant period of time ( step s 313 ), and the verification of the registration of the mobile station 20 by the user 10 is not confirmed , the hnb 30 may time out in a verification period , quit the registration , and resume the standard operation status . subsequent to the button operation by the user 10 ( step s 313 ), the hnb 30 notifies the management subscriber 50 that a mobile station 20 has been newly registered and checks with the management subscriber 50 to verify whether the registration is to be accepted ( step s 315 ). if the management subscriber 50 returns an acceptance reply ( step s 317 ), the hnb 30 transmits the registration information to the hss 40 and registers the mobile station 20 at the csg ( step s 319 ). upon completing this series of operations , the hnb 30 shifts to the standard mode and extinguishes the lamp 32 . it is also contemplated that the hss 40 performs the verification process on the management subscriber 50 in the third embodiment of the present invention . fig5 is another sequence chart illustrating a procedure example to register the mobile station 20 at the hss 40 in accordance with the third embodiment of the present invention ( an example inclusive of a verification procedure of a management subscriber 50 ). fig5 illustrates an example in which the hss 40 performs the verification procedure of the addition by the management subscriber 50 subsequent to the registration procedure of the second embodiment . after the hnb 30 registers at the hss 40 in the second embodiment ( step s 401 ), the hss 40 notifies the management subscriber 50 that a new mobile station 20 has been registered and requests the management subscriber 50 to verify that the management subscriber 50 accepts the registration ( step s 403 ). if the management subscriber 50 returns an acceptance reply ( step s 405 ), the hss 40 determines that the verification has been completed , and then receives the registration , and updates the database of the hss 40 in accordance with the registration from the hnb 30 in step s 401 ( step s 407 ). if no acceptance reply has been received from the management subscriber 50 for a specific period of time , the registration from the hnb 30 in step s 401 is discarded , and the database is not updated . furthermore , the third embodiment further includes as an additional verification step a step of transmitting a mail , a voice communication , or the other means to the management subscriber 50 associated with the hnb 30 to request the management subscriber 50 to verify whether the management subscriber 50 accepts the registration . in this way , security level is increased . in the discussion of the procedure of the first , second , and third embodiments , a mobile station 20 that has not belonged to the csg is registered at the csg . the mobile station 20 that has already been registered at the csg may be deleted from the csg in a similar procedure . in such a case , a telephone number corresponding to each function , different from the specific telephone number corresponding to the registration function of the hnb 30 as the calling telephone number to the hnb 30 , may be used . these telephone numbers predetermined may be simply different from a telephone number for ordinary communication . any telephone number may be designated by the hnb 30 , and “# 11 ” may be set for the registration and “# 12 ” may be set for the deletion , for example . a fourth embodiment is different from the first through third embodiments in the functions of the button 31 and the lamp 32 in the configuration of the hnb 30 of fig1 . fig6 is a sequence chart illustrating a procedure example to delete the mobile station 20 registered at the csg in accordance with the fourth embodiment of the present invention . fig6 illustrates an example in which the hnb 30 deletes the mobile station 20 from the csg in a procedure similar to the procedure of the second embodiment . the user 10 performs a call operation on the hnb 30 at a specific telephone number predetermined first by the mobile station 20 ( step s 501 ). in response to the reception of the call ( step s 503 ), the hnb 30 lights the lamp 32 to prompt the user 10 to perform the button operation ( step s 505 ) to request the user 10 to verify whether the user 10 deletes the registration of the mobile station 20 . the hnb 30 also extracts from the access from the mobile station 20 the mobile station information including the mobile station id of the mobile station 20 ( step s 507 ). the hnb 30 prepares the base station information including the base station id of the hnb 30 itself ( step s 509 ), and thus constructs the registration information addressed to the hss 40 by combining the base station information and the mobile station information ( step s 511 ). if the mobile station 20 is to be deleted , the user 10 performs the button operation ( step s 513 ). if no button operation is performed within a constant period of time ( step s 513 ), and the verification of the deletion of the mobile station 20 by the user 10 is not confirmed , the hnb 30 may time out in a verification period , quit the deletion , and resume the standard operation status . subsequent to the button operation by the user 10 ( step s 513 ), the hnb 30 transmits deletion information to the hss 40 and deletes the mobile station 20 from the csg ( step s 515 ). upon completing this series of operations , the hnb 30 shifts to the standard mode and extinguishes the lamp 32 . in accordance with the fourth embodiment , the mobile station 20 that has been registered at the csg can be deleted in the procedure of the second embodiment . in this way , the hnb 30 not only registers the mobile station 20 to the csg but also deletes the mobile station 20 from the csg in a simple operation . as a result , user friendliness to the user 10 is increased . in the discussion of the procedures of the first , second and third embodiments , a mobile station 20 that has not belonged to the csg is registered at the csg . the verification of the registration status of the current csg and the modification of part of the current csg may be carried out in a similar procedure . in such a case , a telephone number corresponding to each function , different from the specific telephone number corresponding to the registration function of the hnb 30 as the calling telephone number to the hnb 30 , may be prepared . these telephone numbers predetermined may be simply different from a telephone number for ordinary communication . any telephone number may be designated by the hnb 30 , and “# 11 ” may be set for the registration and “# 13 ” may be set for the verification and modification , for example . a fifth embodiment is different from the first through fourth embodiments in the functions of the button 31 and the lamp 32 in the configuration of the hnb 30 of fig1 . fig7 is a sequence chart illustrating a procedure example to verify and correct registration information of the csg in accordance with the fifth embodiment of the present invention . fig7 illustrates an example in which the hnb 30 verifies or corrects the registration information of the mobile station 20 at the csg in a procedure similar to the procedure of the second embodiment . the user 10 performs a call operation on the hnb 30 at a specific telephone number predetermined first by the mobile station 20 ( step s 601 ). in response to the reception of the call ( step s 603 ), the hnb 30 lights the lamp 32 to prompt the user 10 to perform the button operation ( step s 605 ) to request the user 10 to confirm whether the user 10 verifies or corrects the registration information of the mobile station 20 . the hnb 30 also extracts from the access from the mobile station 20 the mobile station information including the mobile station id of the mobile station 20 ( step s 607 ). the hnb 30 prepares the base station information including the base station id of the hnb 30 itself ( step s 609 ), and thus constructs information for use in displaying and modifying the registration information addressed to the hss 40 by combining the base station information with the mobile station information ( step s 611 ). when the registration information of the mobile station 20 is to be verified or corrected , the user 10 performs the button operation ( step s 613 ). if no button operation is performed within a constant period of time ( step s 613 ), and the authentication related to the verification and the correction of the registration information of the mobile station 20 by the user 10 is not confirmed , the hnb 30 may time out in a verification period , quit the verification or correction of the registration information , and resume the standard operation status . subsequent to the button operation by the user 10 ( step s 613 ), the hnb 30 performs a verification operation and a correction operation on the registration content . in response to a display request of the registration status from the user 10 ( step s 615 - 1 ), the hnb 30 references the registration information of the hss 40 ( step s 617 - 1 ). the hss 40 transmits the registration status to the hnb 30 ( step s 619 - 1 ), and the hnb 30 notifies the user 10 of the registration status ( step s 621 - 1 ). also , in response to a content modification request from the user 10 ( step s 615 - 2 ), the hnb 30 transmits modification information to the hss 40 ( step s 617 - 2 ), and the hss 40 modifies the registration content , and transmits a modification result to the hnb 30 ( step s 619 - 2 ). the hnb 30 displays modified registration content to the user 10 ( step s 621 - 2 ). a variety of methods , including an audio guidance or a mail , is considered to display the updated registration content to the user 10 . in accordance with the fifth embodiment , the verification of the registration status of the current csg and the modification of part of the content of the current csg may be performed in the same procedure as the second embodiment . the user 10 can thus easily verify and modify the registration information of the mobile station 20 at the csg . as a result , user friendliness to the user 10 is increased . it is also contemplated that the procedure to verify or correct the registration information of the csg is performed by the hss 40 in the fifth embodiment . fig8 is another sequence chart illustrating a procedure example to verify and correct the registration information with the mobile station 20 enabled to access a database of the hss 40 in accordance with the fifth embodiment of the present invention . subsequent to the button operation by the user 10 ( step s 613 ), the hnb 30 notifies the hss 40 that the mobile station 20 has requested a secure database access ( step s 701 ). the hss 40 permits the mobile station 20 to access the database through means , such as transmitting via a mail a url for use in the secure database access ( step s 703 ). the mobile station 20 displays the url to the user 10 ( step s 705 ). the user 10 then accesses the url provided for the secure database access and is thus enabled to directly access the database ( step s 707 ), and the hss 40 displays the registration status to the user 10 ( step s 709 ). in response to a content modification request from the user 10 ( step s 711 - 1 ), the hss 40 modifies the registration content ( step s 713 - 1 ), and transmits a modification result to the user 10 ( step s 715 - 1 ). upon receiving a display request to display the registration status from the user 10 ( step s 711 - 2 ), the hss 40 displays the registration information thereof ( step s 713 - 2 ). the mobile station 20 accessible to the csg is dynamically managed by facilitating the registration of the mobile station 20 to the csg as described above . in that case , however , an upper limit to the number of mobile stations that can be registered at a single csg becomes a problem . the number of mobile stations 20 already registered may have reached the upper limit in the registration procedure in the first , second , and third embodiments . in such a case , as described below , a sixth embodiment provides additional procedures including discontinuing a new registration , and selecting a mobile station 20 to be deleted from among the registered mobile stations 20 . in a new registration with the registration count reaching the upper limit of the registerable number of mobile stations , a step first contemplated is ( 1 ) discontinuing registration of new mobile stations 20 . the following steps may also be contemplated to cancel a registered mobile station 20 from registration . ( 2 ) prioritizing the mobile stations 20 in the order with a higher priority placed on a mobile station 20 having used the hnb 30 more recently and deleting a mobile station 20 having a lower priority . ( 3 ) prioritizing the mobile stations 20 in the order of registration , for example , with a higher priority placed on an older registration than on a younger registration , or with a higher priority placed on a younger registration than on an older registration , and then deleting a mobile station 20 having a lower priority . ( 4 ) prioritizing the mobile stations 20 in the order with a higher priority placed on a mobile station 20 having a higher count of registrations and then deleting a mobile station 20 having a lower priority . ( 5 ) classifying the mobile stations 20 into two classes , cancelable mobile stations 20 and uncancelable mobile stations 20 , and performing the above step ( 3 ) or ( 4 ). for example , the two classes may be determined during the registration , by preparing two different types of telephone numbers for registration . in accordance with the sixth embodiment , if the number of mobile stations 20 already registered has reached the upper limit in the registration procedure , the additional procedures are performed including discontinuing a new registration or selecting a mobile station 20 to be deleted from among the registered mobile stations 20 . the mobile stations 20 are thus appropriately registered on the hss 40 in view of the upper limit to the registerable number of mobile stations . a program running on the mobile station 20 , the hnb 30 , and the hss 40 of the present invention is a program that controls a cpu ( a program for causing a computer to function ) in a manner such that the functions of the embodiments of the present invention are implemented . information handled by the devices may be temporarily stored on a ram during process , and then stored on a variety of roms or hdd . the information may be read , corrected , or written by the cpu as necessary . recording media storing the program may include semiconductor memories ( such as a rom or a non - volatile memory card ), optical recording media ( such as dvd , mo , md , cd , or bd ), and magnetic recording media ( such as a magnetic tape or a flexible disk ). the functions of the embodiments are implemented by executing the loaded program . the functions of the invention may also be implemented in conjunction with an operating system or another application program in response to an instruction of the program . to circulate the program in the market , the program may be supplied in a stored state on a portable recording medium , or is transferred to a server computer via a network such as the internet . in such a case , a storage device in the server computer also falls within the scope of the present invention . whole or part of the mobile station 20 , the hnb 30 , and the hss 40 may be implemented as lsi as a typical integrated circuit . each function block in the mobile station 20 , the hnb 30 , and the hss 40 may be individually integrated into a chip . alternatively , all or some of the function blocks may be integrated into a chip . the integrated form may not be limited to lsi . the integrated form may be a dedicated circuit , or a general - purpose processor . if a technique of circuit integration replacing the lsi appears with the advance of semiconductor technique , an integrated circuit resulting from the technique may also be used .