KR100905534B1 - System and method for supporting roaming call through automatic call forwarding - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for supporting roaming calls through automatic conversion of called party numbers.

A roaming station transmitter for processing location registration of a calling terminal and receiving a call request message including a called number from a calling terminal; and a roaming station transmitter for transmitting a calling number included in the call request message received through the roaming station transmitter to an international To a called number of a mobile station identification number system. In addition, the present invention uses a country code and a network code stored in a location registration of a calling terminal, or a network code and a network code included in a call request message, to transmit a call destination number included in a call request message to a destination number And then sends it to the home network mobile communication network.

According to the present invention, when a user located at a roaming station transmits a call to a home country, it is possible to use a telephone number or an abbreviated number stored in a terminal without having to input a country code, a network code, have.

Roaming, called number, MCC, MNC, IMSI, country code, network code, international call

Description

TECHNICAL FIELD [0001] The present invention relates to a system and a method for supporting roaming call through automatic call forwarding,

1 is a schematic view of a roaming call support system according to an embodiment of the present invention;

FIG. 2 is a flowchart for explaining a method for automatically converting a called number using subscriber information of a calling terminal according to a first embodiment of the present invention; FIG.

3 is a diagram illustrating a format of an origination request message transmitted from a calling terminal to a roaming station mobile communication network according to an embodiment of the present invention;

4 is a flowchart illustrating a method of automatically converting a called number using a telephone number of a calling terminal according to a second embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for supporting roaming calls through automatic conversion of called party numbers. More specifically, when a call request is received from a subscriber terminal that is roaming abroad to a called terminal located at a home station, even if a destination number that does not include a country code and a network code is transmitted, And more particularly, to a system and method for supporting roaming calls.

Telecommunication service providers providing mobile communication services are classified by country or city, and the system is also variously configured. However, according to the international mobile telecommunication-2000 (IMT-2000) mobile communication service, which is referred to as the third generation, internationally standardized mobile communication standards are being used.

Accordingly, mobile communication providers provide a roaming service for supporting mobile communication services to users who have moved from other countries while sharing and using mobile communication base stations.

The roaming service is provided with an automatic roaming service and a rental roaming service. The automatic roaming is a service type in which a subscriber terminal used by a user is used as it is in a roaming country (hereinafter, referred to as a roaming station) Is a service type in which a subscriber terminal available in the roaming station is rented, and a user's telephone number is input to the rented subscriber terminal.

Particularly, since the third generation mobile communication standard is unified internationally and the standard of the subscriber terminal is also internationally standardized, an automatic roaming service in which a user provides mobile communication service using his / her subscriber terminal in a roaming station is mainly used . However, even if an automatic roaming service is provided, in order for a roaming station to make an international call to a mobile communication service subscription country (hereinafter, referred to as a "home country") prior to roaming, Country code, and network code.

Accordingly, the subscriber can not use the shortcut number or the telephone directory stored in the subscriber terminal, manually inputs the international telephone identification number, the country code, the network code, and the telephone number of the called terminal (hereinafter referred to as the " There is an inconvenience to do.

In order to solve such a problem, according to the present invention, when a subscriber terminal located in a roaming station requests a call to a called terminal located in a home station, even if a subscriber terminal inputs only a called number not including a country code and a network code, The present invention provides a roaming call support system and method for supporting call connection to a home station by converting the telephone number into a telephone number of a mobile station identification number system.

According to a first aspect of the present invention, there is provided a system for supporting a roaming call by converting a called number transmitted from a roaming calling terminal, the system comprising: A roaming station transmitter for receiving a call request message including a called number from an originating terminal; A roaming station home location register or a roaming station visitor location register for temporarily storing subscriber information confirmed through location registration; And if the call request message received from the calling terminal is an international telephone call request message, it transmits the country code and the network code of the calling terminal stored in the roaming station home location register or the roaming terminal visitor location register to the called number To a called number of the international mobile station identification number system.
In addition, the roaming call support system according to the second embodiment of the present invention is a system for supporting roaming call by converting a called number transmitted from a roaming calling terminal, which processes the location registration of the calling terminal, A roaming station transmitter for receiving a call request message including the call request message; When the call request message received from the calling terminal is confirmed to be an international telephone call request message, the country code and the network code included in the telephone number of the calling terminal are confirmed through the call request message and combined with the called number, And a roaming station exchange for converting to the called number of the system.

A method for supporting roaming calls according to a first exemplary embodiment of the present invention is a method for supporting roaming calls by automatically converting a called number transmitted from a roaming calling terminal, Extracting and storing a country code and a network code from the number; (b) confirming whether the destination code includes a country code and a network code when it is confirmed that the call request message is an international telephone call request by confirming whether or not the international call identifier is included; (c) combining the country code of the calling terminal and the network code into the called number included in the call request message and converting the combined code into the called number of the international mobile station identification number system; And (d) sending a call request message including the called number of the international mobile station identification number system to the home network mobile communication network.

According to another aspect of the present invention, there is provided a method of supporting a roaming call by converting a called number transmitted from a roaming calling terminal, the method comprising the steps of: (a) Confirming the country code and the network code of the origination number; (b) converting the country code and the network code into a destination number of the international mobile station identification number system by combining the country code and the network code with the destination number included in the call request message; And (c) transmitting a call request message including the called number of the international mobile station identification number system to the home network mobile communication network.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Also, when a part is referred to as " including " an element, it does not exclude other elements unless specifically stated otherwise.

FIG. 1 is a schematic diagram of a roaming call support system according to an embodiment of the present invention. Referring to FIG.

The roaming call support system according to an embodiment of the present invention includes a calling terminal 110, a roaming mobile communication network 120, an international roaming gateway 130, a home mobile communication network 140, and a called terminal 150.

In order to clarify the explanation, the call request message transmitted from the calling terminal 110 to the roaming mobile communication network 120 is referred to as a 'origination request message', and the roaming mobile communication network 120 transmits an international roaming The call request message transmitted to the gateway 130 is called an origination request signal and the call request message transmitted from the international roaming gateway 130 to the home mobile communication network 140 is called an incoming call request signal, The call request message transmitted from the call terminal 140 to the called terminal 150 will be referred to as an 'incoming request message'.

The roaming station mobile communication network 120 is a network for providing a mobile communication service in a roaming station and performs location registration of the roaming origination terminal 110. The roaming station mobile communication network 120 identifies a home station through an origination request message from the originating terminal 110 And requests a call to the home network mobile communication network 140 through the international roaming gateway 130. In addition, the roaming mobile communication network 120 determines whether the called terminal number included in the origination request message received from the calling terminal 110 includes a mobile country code (MCC) and a mobile network code (MNC) It inserts the country code and the network code, which are confirmed when receiving the origination request message from the originating terminal 110 or the originating terminal 110, and transmits the inserted country code and network code to the international roaming gateway 130.

To this end, the roaming station mobile communication network 120 includes a roaming station transmitter 1210, a roaming station controller 1220, a roaming station switch 1230, a roaming home location register (HLR) A visitor location register 1240, and a roaming station visitor location register (VLR) 1250.

The roaming station transmitter 1210 performs location registration for identifying the location of a subscriber station existing in a cell area to which the mobile station is to be controlled, receives a call request message from the calling terminal 110 via a traffic channel, And then transmits the resultant data to the controller 1220. That is, the roaming station transmitter 1210 is a network end point device that performs baseband signal processing, wired / wireless conversion, and wireless signal transmission and reception and is directly connected to the calling terminal 110.

Here, the location registration is a processing procedure for informing the roaming station switch 130 through the roaming station transmitter 1210 of the location, state, identifier, slot period, and other characteristics of the calling terminal 110. The terminal information of the calling terminal 110 is stored in the roaming station VLR 1250. When the roaming station transmitter 1210 attempts to set an incoming call to the calling terminal 110, The calling terminal 110 can be effectively called using the subscriber information of the calling terminal 110 stored in the calling terminal 1250.

The roaming station controller 1220 controls the roaming station transmitter 1210 and performs a function of allocating a radio channel for providing a mobile communication service to the calling terminal 110. In addition, the roaming station controller 1220 transmits the subscriber information and the origination request message of the calling terminal 110, which are transmitted at the time of location registration, to the roaming station switch 1230.

The roaming station switch 1230 performs various service processing and call processing provided by the roaming station mobile communication network 120 and controls the roaming station controller 1220, the roaming station HLR 1240, the roaming station VLR 1250 And management. Accordingly, the roaming station switch 1230 receives the subscriber information transmitted through the roaming station controller 1220 according to the location registration of the subscriber terminal, and temporarily stores the subscriber information in the roaming station VLR 1250 or the roaming station HLR 1240 Role.

When the telephone number of the called terminal that does not include the country code and the network code is transmitted through the origination request message according to the embodiment of the present invention, the roaming station switching center 1230 transmits the roaming station VLR 1250 or the roaming station HLR 1240 using the country code and the network code of the calling terminal 110 transmitted through the country code and the network code of the calling terminal 110 stored in the calling terminal 110 or the calling terminal 110, Converts it into an International Mobile Station Identity (IMSI), and transmits it to the international roaming gateway 130.

The roaming station HLR 1240 is a database for storing subscriber information registered in the roaming station mobile communication network 120.

When the subscriber terminal located in the roaming station mobile communication network 120 performs location registration, the roaming station VLR 1250 temporarily stores the received subscriber information and transmits the subscriber information via the subscriber information exchange with the roaming station HLR 1240, Position control, call processing, and external operation processing.

Accordingly, the subscriber information transmitted according to location registration performed by the calling terminal 110 roaming from another country other than the subscriber of the roaming station mobile communication network 120 may be transmitted to the roaming station HLR 1240 or the roaming station VLR 1250, Lt; / RTI >

The international roaming gateway 130 is a gateway for interconnecting mobile communication networks served in a plurality of countries. That is, the roaming mobile communication network 120 and the home mobile communication network 140 are connected to each other through the international roaming gateway 130, thereby providing a call service between the roaming mobile communication network 120 and the home mobile communication network 140 .

At this time, the international roaming gateway 130 confirms the country code of the international mobile station identification number system transmitted from the roaming mobile communication network 120, and connects the mobile communication network of the identified country to the roaming mobile communication network 120 . Also, it can check the network code and connect to the confirmed network.

The home country mobile communication network 140 includes a home country exchange 1410, a home country HLR 1420, a home country controller 1430, and a home country transmitter 1440, which are mobile communication networks operated in a country where the calling terminal 110 is a mobile communication service subscriber. do.

The home country exchange 1410 processes various services and calls provided by the home network mobile communication network 140. Accordingly, when an incoming call request signal is transmitted through the international roaming gateway 130 according to the embodiment of the present invention, after confirming the called number included in the incoming call request signal, the subscriber information is confirmed through the home HLR 1420, And transmits a call reception request message to the parent station controller 1430 responsible for the cell in which the called terminal 150 is located.

The home station HLR 1420 is a database for storing subscriber information registered in the home network mobile communication network 140 and stores subscriber information of the calling terminal 110 and the called terminal 150.

The parent station controller 1430 controls the parent station transmitter 1440 and transfers the call request message transmitted from the parent station exchange 1410 to the parent station transmitter 1440.

The parent station transmitter 1440 transmits the call request message received from the parent station controller 1430 to the called terminal 150 located in the cell area to which the parent station controller 1430 belongs and supports the call through the wireless signal transmission / It is a network termination device.

Through the roaming call support system having the above-described structure, the routing information including the country code and the network code transmitted through the origination request message from the roaming calling terminal 110 can be referred to as a destination number of the international mobile station identification number system (IMSI) Can be automatically converted.

In this case, a method of automatically converting a called number by inserting a country code and a network code included in subscriber information transmitted at the time of location registration of the calling terminal 110 in converting to a called number of the international mobile station identification number system, A method of automatically converting the called number by inserting the country code and the network code included in the calling number transmitted together with the message may be used.

2 is a flowchart illustrating a method of automatically converting a called number using subscriber information of a calling terminal according to a first embodiment of the present invention.

When the user who has moved to the roaming station applies power to the calling terminal 110 to receive the mobile communication service, the calling terminal 110 transmits subscriber information to the roaming mobile communication network 120 and performs location registration do.

The telephone number of the calling terminal 110 is transmitted to the subscriber information transmitted at the time of location registration. In this case, the telephone number of the originating terminal 110 to be transmitted is a telephone number of the international mobile station identification number system including the country code and the network code, and the roaming station mobile communication network 120 transmits the country code included in the telephone number, Country mobile communication network 140 of the calling terminal 110 through the code. The received subscriber information is temporarily stored in the roaming station HLR 1240 or the roaming station VLR 1250 (S200).

When the calling terminal user located at the roaming station inputs the telephone number and the call request button of the called terminal 150 for the call with the called terminal 150 located in the home station, an origination request message is transmitted to the roaming station transmitter 1210 And the origination request message received at the roaming station transmitter 1210 is transmitted to the roaming station switch 1230 through the roaming station controller 1220. [

At this time, according to the embodiment of the present invention, the calling terminal user can input the called number not including the country code and the network code. That is, the calling terminal user may select a telephone directory stored in the calling terminal 110 or a preset dialing number for use in the home network mobile communication network 140, and accordingly, a 7-digit Or an 8-digit destination number, or a 10-digit or 11-digit destination number that does not include a country code, may be included in the origination request message and transmitted.

When the origination request message is received from the originating terminal 110 in step S210, the roaming station switch 1230 determines whether the origination request message is an international call request signal for requesting a call to the destination terminal 150 located in the home station do.

The originating request message includes an identifier (hereinafter, referred to as an 'international telephone identifier') indicating whether the requested call request is an international telephone call. The roaming station switch 1230 confirms the international telephone identifier, It is possible to confirm whether or not the request message requests an international call. Here, the international telephone identifier is generated when an international telephone connection number set in advance (e.g., 001, 002, 00345, 00700, etc.) or an international telephone connection code (e.g., '+' or the like) is input (S220).

If it is determined that the received international call identifier is included in the received origination request message at step S230, the country code and the network code of the subscriber information temporarily stored in the roaming station HLR 1240 or the roaming station VLR 1250 (S240).

In step S250, when the country code and the network code of the calling terminal 110 are confirmed, the called party number is combined with the received country code or network code in step S210 to generate a called number of the international mobile station identification number system.

Then, the roaming station mobile communication network 120 transmits an origination request signal together with the called number of the international mobile station identification number system to the international roaming gateway 130 (S260).

Upon receipt of the origination request signal, the international roaming gateway 130 confirms the country code of the called number, confirms the home network mobile communication network 140, and transmits the arrival request signal to the confirmed home mobile communication network 140 (S270).

The home network mobile communication network 140 receiving the call request signal from the international roaming gateway 130 confirms the subscriber information of the called terminal 150 having the called number using the home HLR 1420. At this time, the location of the called terminal 150 can be checked using the home country VLR (not shown) of the home country mobile communication network 140.

When the location of the destination terminal 150 is confirmed, a call setup is requested to the destination terminal using the parent station controller 1430 and the parent station transmitter 1440, and a session for the call is established, (Step S280).

However, if it is confirmed in step S230 that the received international call identifier is not included in the origination request message, it is confirmed that the origination request message is in the roaming station, and the subscriber information of the called terminal using the roaming HLR 1240 And provides a call service by setting up a call (S290).

In step S270, the international roaming gateway 130 extracts the country code from the origination request signal before transmitting the call origination request signal to the home country mobile communication network 140, It is also possible to set an incoming call request signal to be transmitted to the home network mobile communication network 140.

3 is a diagram illustrating a format of an origination request message transmitted from a calling terminal to a roaming station mobile communication network according to an embodiment of the present invention.

An origination request message transmitted from the calling terminal 110 to the roaming mobile communication network 120 according to an embodiment of the present invention includes a preamble 310, an access channel message field 320, and a padding 330.

The preamble 310 and the padding 330 are fields in which information is not included. The preamble 310 is located in the front part of the message and prevents data loss due to transmission delay. The padding 330, Is a field that is positioned at the rear of the message and serves to adjust the message length to a specific length.

The access channel message field 320 includes the contents of the transmitted origination request message and includes a message size MSG_Length field 330, a data field MSG_Body field 340 and a cyclic redundancy checking (CRC) .

The message size field 330 indicates the size of the transmitted request message or the size of the data field 340.

The data field 340 includes the data to be transmitted through the origination request message and includes an originating telephone number field 360, an incoming telephone number field 370, a pilot information field 380 and a mandatory message field 390 .

The originating telephone number field 360 is a field for displaying the telephone number of the calling terminal 110 transmitting the origination request message and includes a country code display field 3610, a network code display field 3620, and a calling MSIN Number) display field 3630. FIG.

The country code display field 3610 is a field for displaying the country code assigned to the parent country. The country code is composed of three digits in front of the originating telephone number according to the international mobile station identification number system, and the country code display field 3610 may have a size of 10 bits.

The network code display field 3620 is a field for displaying the network code allocated to the home network mobile communication network 140. [ The network code is composed of 2 to 3 digits after the country code according to the international mobile station identification number system. For this purpose, the network code display field 3620 may have a size of 7 bits or 10 bits.

The calling MSIN display field 3630 is a field for displaying a directory number uniquely assigned to the calling terminal 110. [ The directory number is a unique designation number assigned to each terminal, and is configured to be within 10 digits. For this purpose, the MSIN display field 3630 may be implemented with a size of 34 bits or less.

The called telephone number field 370 is a field for displaying the telephone number of the called terminal 150 as a call request subject. The incoming telephone number field 380 according to the present invention includes an international telephone ID field 3710, Field 3720. [

When the calling terminal 110 inputs an international telephone connection number or an international telephone connection symbol that is input in front of the destination number in order to attempt an international telephone call, the international telephone ID field 3710 is used to make an international telephone call to the roaming station mobile communication network 120 Including the international call identifier that is generated to notify that the call has been received. The international call identifier field 3710 may be implemented with a size of 1 bit to indicate only an international call or may be implemented with a plurality of bits to include an international call connection number or a symbol.

The incoming MSIN display field 3720 is a field including the directory number of the called terminal 150 input by the calling terminal 110. [

Here, when the calling terminal 110 inputs the telephone number of the called terminal 150, only the directory number may be input using the address number or telephone directory, the network code and the directory number may be input, , You can enter both network code and directory number.

To this end, an incoming country code display field and a destination network code display field may additionally be configured between the international telephone identifier field 3710 and the incoming MSIN display field 3720 of the incoming telephone number field 370.

Alternatively, when one or more of the country code and the network code is additionally input in the calling terminal 110, the calling terminal may be included in the incoming MSIN indication field 3720 together with the directory number. At this time, the size of the incoming MSIN indication field 3720 can be implemented up to 56 bits.

Here, according to the setting in the calling terminal 110 or the setting in the roaming mobile communication network 120, a call request to the home network communication network 140 can be transmitted even if there is no input of an international telephone connection number or an international telephone connection symbol May be set. In such a case, it is also possible to omit the international telephone identifier field 3710 in the incoming telephone number field 370.

The pilot information field 380 is a portion including pilot information such as transmission / reception power and delay time exchanged with the roaming mobile communication network 120 through the pilot signal at the calling terminal 110.

The mandatory message field 390 is a part including various information necessary for transmission of the origination request message. The essential message field 390 includes various information except for information transmitted and received through the pilot signal such as a protocol revision level, a system IDentification (SID), a network ID (NID) A Pilot PN Offset Index, a System Time, and a Paging Channel Data Rate (PRAT).

The CRC field 350 is a field included for error detection for reliability verification of the transmitted origination request message.

Upon receiving the origination request message having such a structure, the roaming mobile communication network 120 can automatically convert the called number using the country code and the network code included in the origination phone number field 360.

4 is a flowchart illustrating a method of automatically converting a called number using a telephone number of a calling terminal according to a second embodiment of the present invention.

The roaming station mobile communication network 120 confirms the called number included in the data field 340 of the origination request message through the roaming station switch 1230 (step S400) when the origination request message is transmitted from the calling terminal 110 S410).

Then, in the incoming call number field 370, it is determined whether or not the international call identifier exists in the international call identifier field 3710, and it is determined whether the requested call request is an international call (S420).

If it is confirmed that the received ID message is included in the received origination request message at step S430, the calling terminal 110 transmits the ID code to the calling terminal 110 through the country code display field 3610 and the network code display field 3620 of the origination phone number field 360 (Step S440).

The called country code, the network code, and the directory number of the called terminal 150 identified in the called telephone number field 370 are combined to generate the called number of the international mobile station identification number system.

At this time, if the incoming telephone number includes the network code in step S420, it is possible to generate the called number of the international mobile station identification number system by combining only the country code identified in step S440 with the confirmed incoming telephone number. If the incoming telephone number includes both the network code and the country code through step S420, the step of combining with the incoming telephone number may be omitted (S450).

When the called number of the international mobile station identification number system is generated, the roaming station mobile communication network 120 transmits an origination request signal together with the called number of the international mobile station identification number system to the international roaming gateway 130 (S460).

The international roaming gateway 130 having received the origination request signal confirms the country code of the called number to confirm the home country mobile communication network 140 and transmits an incoming call request signal to the confirmed home country mobile communication network 140 at step S470.

The home network mobile communication network 140 which has received the reception request signal from the international roaming gateway 130 establishes a session with the called terminal to provide a call service between the calling terminal 110 and the called terminal 150 S480).

If it is determined in step S430 that the international call identifier is not included in the received origination request message as a result of checking the international call identifier field 3710, it is confirmed that the origination request message is in the roaming station, 1240), and sets up a call to provide a call service (S490).

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

As described above, according to the present invention, when a user who has moved to another country makes a call to a specific recipient of the home country, it is possible to transmit the telephone number or the shortcut number The convenience of using the roaming service is provided.

Also, there has been provided a technique of converting a self-inputted called number into an international mobile station identification number system in a calling terminal. However, according to the embodiment of the present invention, by converting the called number entered in the roaming mobile communication network into the international mobile station identification number system, it is possible to reduce the radio resources used in transmitting the call request signal from the calling terminal to the roaming station mobile communication network , And performs a telephone number conversion operation in an exchange having better performance than the terminal, so that a quick conversion operation can be performed.

In addition, since it is not easy to charge a battery of a terminal in a foreign country, a technique of reducing battery consumption is required. According to the embodiment of the present invention, battery operation can be reduced by minimizing the operation performed in the terminal.

Claims (17)

A system for supporting a roaming call by converting a called number transmitted from a roaming calling terminal, A roaming station transmitter for processing the location registration of the calling terminal and receiving a call request message including the called number from the calling terminal; A roaming station home location register or a roaming station visitor location register for temporarily storing subscriber information confirmed through the location registration, wherein the subscriber information temporarily stores the country code and the network code of the calling terminal; And When it is determined that the call request message received from the calling terminal is an international telephone call request message, transmits the country code and the network code of the calling terminal stored in the roaming station home location register or the roaming terminal visitor location register to the call request message A roaming station exchange, which, in combination with the included called number, converts it to the called number of the international mobile station identification number system The roaming call support system comprising: delete The method according to claim 1, The roaming station exchange includes: Wherein whether the call request message is an international call request message is checked through whether or not the call request message includes an international call identifier. delete delete The method according to claim 1, The roaming station exchange includes: Wherein the base station mobile communication network transmits the call request message including the called number of the converted international mobile station identification number scheme to the home mobile communication network, wherein the home mobile communication network is a mobile communication service subscription state of the calling terminal. Roaming call support system. The method according to claim 6, And an international roaming gateway for confirming the home country mobile communication network using the country code included in the reconfigured call request message and connecting the mobile communication network of the region where the confirmed home country mobile communication network and the called terminal are roaming, Wherein the roaming call support system further comprises: A method for supporting a roaming call by automatically converting a called number transmitted from a roaming calling terminal, (a) extracting and storing the country code and the network code from the telephone number of the calling terminal received through the location registration of the calling terminal, where the telephone number of the calling terminal is the telephone number of the international mobile station identification number system step; (b) confirming whether the called number includes the country code and the network code when it is confirmed that the call request message is an international telephone call request by checking whether the international call identifier is included; (c) combining the country code of the calling terminal and the network code into the called number included in the call request message, and converting the called number into the called number of the international mobile station identification number system; And (d) sending a call request message including the called number of the international mobile station identification number system to the home country mobile communication network, wherein the home country mobile communication network is a mobile communication service subscription country of the calling terminal; The method comprising the steps of: delete delete 9. The method of claim 8, If the destination number does not include both the country code and the network code in step (b), the step (c) Calling the stored country code and network code, and combining the stored country code and network code with the called number to convert the called number into the called number of the international mobile station identification number system. 9. The method of claim 8, If the called number does not include only the country code in step (b), the step (c) Calling the stored country code and combining with the called number to convert the called number into the called number of the international mobile station identification number system. 9. The method of claim 8, The step (d) (d1) transmitting a call request message including the called number of the international mobile station identification number system to an international roaming gateway; (d2) checking the country code in the international roaming gateway to identify the home country mobile communication network; (d3) transmitting the call request message to the home network mobile communication network; And (d4) establishing a call session with the called terminal located in the home network mobile communication network Wherein the roaming call support method comprises the steps of: delete delete delete delete

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