JP2005057518A - Roaming call control system of mobile terminal, and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a user to select a desired provider out of traders with which the user makes roaming contracts by himself or herself as much as possible without the need for alterations of a current system on provider sides. <P>SOLUTION: Provided is a contract provider table 15 in which priority levels to be used are set by wireless communication networks in a wireless network 901 that the provider provides, and a control part 11 confirms, at the time of origination, whether the user is in a service area of the wireless communication network in order from the service area having the top priority set in the contract trader table 15 and selects the wireless communication network wherein the presence in the service area is confirmed in such a case to make a call connection request. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a roaming call control method and method for a mobile terminal, and more particularly to a mobile terminal that selects a plurality of providers that provide a wireless communication network according to the priority set for each wireless communication network when making a call. The present invention relates to a roaming call control method and method thereof.

  For example, Japanese Unexamined Patent Application Publication No. 09-018963 discloses a mobile phone system for switching a wireless communication network provided by a conventional business operator. That is, the system described in Japanese Patent Application Laid-Open No. 09-018963 uses a single wireless communication network, which is a normal method for transmission in a PHS system, and selects an operator in response to the base station side. Yes.

  Further, as a mobile phone system for switching a wireless communication network provided by a conventional business operator, for example, it is disclosed in Japanese Patent Application Laid-Open No. 2000-300653. That is, according to this Japanese Patent Laid-Open No. 2000-300653, the mobile terminal apparatus receives the received electric field strength / error rate of the received electric field strength / received signal error rate of the wireless communication network provided by each of a plurality of contractors. Select a wireless communication network with a higher received field strength or lower received signal error rate from wireless communication networks provided by multiple contractors based on the detected received field strength and error rate. It is described that a connection request is made.

JP 09-018963 A

Japanese Patent Laid-Open No. 2002-300653

  However, according to Japanese Unexamined Patent Publication No. 09-01863, which is the above-mentioned prior art, for example, in the case of PDC, since the operator is selected on the base station side at the start of transmission, the user himself / herself selects the operator during the transmission procedure. There is a problem that it cannot be switched. In addition, in the current system, there is no method for notifying the base station of the selection of the operator, and therefore there is a problem that the system needs to be changed when realized by the PDC system.

  In addition, according to Japanese Patent Application Laid-Open No. 2002-300653, which is the above-described prior art, in order to unconditionally select a wireless communication network with a high received electric field strength or a low error rate of a received signal at the time of transmission from a mobile terminal device, There is a problem that even if the user wants to use the wireless communication network of a business operator that does not affect the call, the user cannot select it.

  In view of the above-described problems, the object of the present invention is to perform wireless communication of a business operator desired by the user himself as much as possible among business operators who have a roaming contract without requiring any change on the business operator side in the current system. It is to realize the selection of the network.

  Another object of the present invention is to improve operability by automatically switching roaming operations in view of the above problems.

  In order to achieve the above object, a roaming call control method in a first portable terminal according to the present invention is a roaming call control method in a portable terminal contracted with a plurality of operators providing respective wireless communication networks. Setting means for setting the priority order to be used for each wireless communication network provided by the article trader, and whether there is in order from the service area of the wireless communication network having the highest priority set by the setting means at the time of outgoing call Confirmation means for confirming, and connection means for making a call connection request by selecting the wireless communication network first confirmed to be present within the service area if it exists within the service area in the process of sequentially confirming by the confirmation means, It is characterized by having.

  Furthermore, the roaming call control system in the first portable terminal is characterized by comprising display means for displaying a name of a provider providing the wireless communication network selected by the connection means.

  Also, the roaming call control method in the second portable terminal of the present invention is a roaming call control method in a portable terminal contracted with a plurality of providers providing respective wireless communication networks, and the wireless provided by the provider is provided. A setting means for setting a priority order to be used for each communication network, a first confirmation means for confirming whether a service area of a wireless communication network currently in use exists at the time of transmission, and the first confirmation means. A second confirmation unit for confirming whether the priority of the wireless communication network currently in use is the highest if present in the vicinity, and the setting unit if the priority is not the highest in the second confirmation unit The third confirmation means for confirming whether or not the wireless communication network having the highest priority set in the service area is in the service area in order, and in the process of confirming in turn by the third confirmation means It is characterized by having a first selecting the wireless communication network is detected to be present within the first connection means for performing a call connection request, a do.

  Further, in the roaming call control system in the second portable terminal, if the wireless communication network that is currently in use does not exist even if the third confirmation means sequentially confirms, a call connection request is made by selecting the currently used wireless communication network. It has the 2nd connection means to perform, It is characterized by the above-mentioned.

  Furthermore, the roaming call control system in the second portable terminal is characterized by comprising display means for displaying a name of a provider providing the wireless communication network selected by the first connection means.

  Further, in the roaming call control method in the first or second portable terminal, the determination as to whether the wireless communication network is within range is made if the received electric field strength of the wireless communication network is equal to or higher than a specified value. It is characterized by being out of range if it exists in the area and is less than the specified value.

  The roaming call control method in the first portable terminal of the present invention is a roaming call control method in a portable terminal that has contracted with a plurality of carriers that provide respective wireless communication networks, and is provided by a carrier that has contracted for roaming. Preparing a table in which a wireless communication network to be set for each business operator is set in the mobile terminal, and setting a priority order to be used for each wireless communication network provided by the business operator in the table; Sequentially searching for the wireless communication network with the highest priority set in the above, and checking in order whether the service area of the searched wireless communication network exists in the service area, and checking the order by searching the table Selecting a wireless communication network that is first confirmed to be in the service area if it exists in the service area, and making a call connection request. It is characterized by a door.

  Also, the roaming call control method in the second portable terminal of the present invention is a roaming call control method in a portable terminal contracted with a plurality of providers providing respective wireless communication networks, provided by the provider who has made a roaming contract. Preparing a table in which the wireless communication network to be set for each operator is set in the mobile terminal, setting the priority to be used for each wireless communication network provided by the operator in the table, Checking whether the service area of the currently used wireless communication network exists within the service area, and if the service area of the currently used wireless communication network exists within the service area, the priority order of the currently used wireless communication network is A step of confirming whether the priority is the highest, and the highest priority set in the table if the priority of the wireless communication network currently in use is not the highest A step of sequentially searching the wireless communication network and confirming in order whether the service area of the searched wireless communication network exists within the range, and first checking if there is a range within the process of checking the table in order Selecting the wireless communication network that has been confirmed to exist in the vicinity and making a call connection request.

  Further, in the roaming call control method in the second mobile terminal, the wireless communication network that is currently in use is selected if there is nothing in the range in the process of sequentially checking the table by searching the table. Then, a call connection request is made.

  The roaming call control method in the first or second portable terminal further includes a step of displaying a name of a provider providing the wireless communication network when the wireless communication network is selected and a call connection request is made. It is characterized by.

  Furthermore, in the roaming call control method in the first or second portable terminal, the determination as to whether the wireless communication network is within range is made if the received electric field strength of the wireless communication network is equal to or higher than a specified value. It is characterized by being out of range if it exists in the area and is less than the specified value.

  On the other hand, according to the present invention, the mobile terminal prepares a table in which the priority of selection of the operator who has a roaming contract is set, and according to the priority, the received electric field strength is set at the time of transmission of the mobile terminal itself. Since the wireless communication network of the carrier with the highest priority is automatically selected from the wireless communication networks of the carrier that has obtained a certain reception strength by comparing with the specified value, the carrier in the current system There is an effect that there is no need to change the side. Further, there is an effect that the wireless communication network of the business operator desired by the user can be selected as much as possible among the business operators that have roaming contracts.

  Further, according to the present invention, the mobile terminal prepares a table in which the priority of selection of the operator who has roaming contract is set, and according to the priority, the received electric field strength is set to the specified value at the time of transmission of the mobile terminal itself. The wireless communication network of the operator with the highest priority is automatically selected among the wireless communication networks of the operators that have obtained a certain reception strength by comparing with the roaming operation automatically. Thus, the operability is improved.

Next, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
Referring to FIG. 1, a wireless network 901 includes a plurality of wireless communication networks provided for each wireless carrier, and a plurality of mobile terminals 10 that are connected to the wireless network 901 and exchange data.

  1 includes a wireless unit 12, a key input unit 13, a control unit 11 that operates under program control by a processor (CPU) (not shown), a display unit 14, a contractor table 15, A usage state area 16 and a voice processing unit 17 for encoding / decoding voice data for exchanging voice data with the control unit 11 for a handset or transmitter (not shown).

  The control unit 11 includes a wireless control unit 112, a key control unit 113, and an operation control unit 111.

  The contract provider table 15 and the usage state area 16 are allocated in a nonvolatile memory (for example, a flash memory) not shown.

  As shown in FIG. 2, the contract operator table 15 receives a roaming service for each contract operator and an area of the operator ID indicating the identity of the contract operator with whom the user of the mobile terminal 10 has a roaming contract. A priority area indicating priority and a channel area indicating a wireless communication network (a wireless communication network is also referred to as a channel) provided by a contractor are allocated. The operator ID and the channel of the contract operator table 15 are set by the roaming service provider side, the dealer, etc. at the time of the roaming contract, and the priority order of the contract operator table 15 is input according to the menu screen on the user side. It is set by doing.

  The usage status area 16 is assigned with each area of the currently used business operator ID and its channel so that the mobile terminal 10 itself can identify the wireless communication network of the contract business operator currently in use. It has become.

  In the present embodiment, the wireless control unit 112 controls the wireless unit 12 and manages the business operators that are on standby. When performing a transmission operation, the user performs a key operation from the key input unit 13, notifies the operation control unit 111 from the key control unit 113 that has received this key input, and performs a transmission operation through the wireless control unit 112 and the wireless unit 12. Is done. In the present invention, when a transmission operation is performed, the operation control unit 111 determines whether the operation is a transmission operation, and notifies the wireless control unit 112 of the transmission. Receiving the notification, the wireless control unit 112 determines the appropriateness of the wireless communication network (channel) used in the roaming service, selects the operator's wireless communication network (channel) from the wireless network 901, and performs call processing. As a transmission operation in this case, there are a method of dialing by inputting the numeric keypad of the key input unit 13, and a method of selecting and transmitting from the address book displayed on the display unit 14 by key operation.

  Next, the operation of the best mode for carrying out the present invention will be described with reference to the drawings.

  First, when the user makes a roaming contract for the mobile terminal 10, all the carrier IDs and roaming contracts (for example, a wireless communication network in the wireless network 901) made by a personal computer via an interface in the mobile terminal 10 (not shown), for example. ) Is transmitted, the control unit 11 of the mobile terminal 10 sets the carrier ID in the area of the carrier ID in the contract carrier table 15, the channel corresponding to the carrier ID in the channel area, and the carrier ID. Set for each.

  When the user turns on the mobile terminal 10 after the contract procedure is completed, the wireless control unit 112 enters the contract operator table 15 in the channel signal received from the wireless network 901 received by the wireless unit 12. The electric field strength of the received signal of the set channel is measured via the wireless unit 12, and the measured received electric field strength is set to a specified value (for example, set to factory shipment) in a non-volatile memory not shown. If it is higher, the channel registered in the contract operator table 15 and set with a higher priority is selected, and the selected channel and the operator ID are set in the use state area 16. . In this case, if the priority order is not set, the wireless control unit 112 selects the channel having the strongest received electric field strength, and sets the selected channel and its operator ID in the use state area 16. In this case, the operator ID may be extracted from a signal on the channel, or may be extracted from the contract operator table 15 based on the channel.

  On the other hand, the user causes the display unit 14 to display menu screen information stored in a nonvolatile memory (not shown) with respect to the operation control unit 113 by an operation from the key input unit 13. Further, according to the displayed menu screen, the user can display the roaming priority setting screen information stored in the non-volatile memory (not shown) for the operation control unit 113 by the operation from the key input unit 13 on the display unit 14. When the priority order (for example, numerical values are sequentially input from “1”. The lower the numerical value is, the higher the priority order) is set according to the displayed roaming priority order setting screen. The unit 111 sets the numerical value input by the user in the priority order area corresponding to the provider ID in the contract provider table 15.

  In such a state, when an interruption occurs in the operation control unit 111 due to a change in the state of the mobile terminal 10 itself, the operation control unit 111 analyzes the cause of the interruption, and if it is an outgoing operation, the user has input or selected The telephone number of the other party is temporarily stored in a predetermined area in a non-volatile memory (not shown), and a call instruction (call notification) is sent to the radio control unit 112. Then, the wireless control unit 112 that has received the instruction confirms whether or not the received electric field strength of the channel read from the use state area 16 is greater than the specified value in order to confirm whether or not the service area of the channel of the operator currently in use is within range. It is judged whether it is high. In this case, the radio control unit 112 determines that the received electric field strength is high, and determines that the area is out of the service area, and the received electric field strength is low, determines that the area is out of the service area. (Steps S101 to S103 in FIG. 3).

  In step S103, if it is within a range, the wireless control unit 112 extracts the priority order of the contracted business operator table 15 using the current business operator ID as a key, and whether or not the extracted value is “1”. By confirming whether or not the priority is the highest. (Steps S104 and S105).

  In step S105, if the priority is not the highest, the wireless control unit 112 confirms whether or not switching to the operator ID having the highest priority is possible (selectable). That is, the radio control unit 112 can switch by extracting the channel with the highest priority from the contractor table 15 and confirming whether the received electric field strength of the extracted channel is higher than the specified value (selection is possible). Is possible). (Steps S106, S107).

  In step S107, if the received electric field strength is higher than the predetermined value, radio control section 112 determines that switching is possible, and the channel and operator ID that are switchable (selectable) are currently in use. Registered in the use state area 16 as the user's channel. (Step S108).

  Further, the wireless control unit 112 reads the channel (wireless communication network) of the carrier ID that can be switched (selectable) from the use state area 16, and uses the read channel from the nonvolatile memory (not shown). The connection destination telephone number (the telephone number temporarily stored in the processing of steps S101 to S103) is read out and a call connection request (outgoing) is made. When a call connection is established with the other party, the wireless control unit 112 exchanges audio data between the other party that is call-connected via the wireless unit 12 and the voice processing unit 17. (Steps S109 and S120).

  In step S107, if the received electric field strength is not higher than the specified value, the radio control unit 112 determines that switching to the provider ID providing the measured channel is impossible (selection is impossible), and step It is confirmed whether or not a channel with a high priority following the priority that is no longer possible in S107 is registered in the contractor table 15. (Step S110).

  If it is registered in step S110, the wireless control unit 112 confirms whether or not it is possible to switch to a high-priority operator ID following the priority that is no longer possible in step S107 (can be selected). . (Steps S111 and S107). In this case, if it is not possible in step S107, the wireless control unit 112 continues until it is confirmed that the next high-priority operator ID is not registered.

  If it is not registered in step S110, the wireless control unit 112 reads the channel (wireless communication network) of the operator currently in use from the usage state area 16, selects the read channel, and stores the nonvolatile channel (not shown). The telephone number of the connection destination (the telephone number temporarily stored in the processing of steps S101 to S103) is read out from the memory and a call connection request (outgoing) is made. When the call connection is established with the other party, the radio control unit 112 displays the selected operator ID (name of the operator) on the display unit 14 and the other party and the voice processing unit that are call-connected via the radio unit 12. Audio data is exchanged with 17. (Steps S110 and S120).

  In step S105, if the priority is the highest, the wireless control unit 112 selects the channel read from the use state area 16 (in this case, the channel having the highest priority) from the non-volatile memory (not shown). The connection destination telephone number (or the center connection destination address) is read out and a call connection request (outgoing) is made. When connected to the other party, the wireless control unit 112 displays the selected operator ID (name of the company) on the display unit 14, and the other party connected via the wireless unit 12 and the voice processing unit 17 Exchange voice data between the two. (Steps S109 and S120).

  Next, a case where a contract is made with a plurality of business operators will be described with an example. As an example, in the case where the user of the mobile terminal 10 has contracted with the operators A, B, and C, the contract operator table 15 includes the operators A, 3, It is assumed that ch-a is registered with business operators B and 1, ch-b, and business operators C, 2, and ch-c. In this case, the priority is set according to a menu screen displayed on the display unit 14 from the key input unit 13 by the user.

  Now, the mobile terminal 10 is located in the wireless service zone of the operator A (within the area), within the wireless service zone of the operator C (within the area), and outside the wireless service zone of the operator B (out of the area). Assume that the operator B and the operator C want to make a call after receiving the incoming call at the operator A. When receiving an incoming call at the operator A, the radio control unit 112 sets the operator A in the operator ID in the use state area 16 and ch-a as the channel. In such a state, when the user performs a transmission operation and the business operator B cannot make a call, an operation of selecting the business operator C and performing a transmission will be described with reference to FIG.

  When an interrupt occurs in the operation control unit 111 via the key control unit 113 due to a change in the state of the mobile terminal 10 itself, the operation control unit 111 analyzes the interrupt factor. As a result of the analysis of the interrupt factor, the operation control unit 111 issues a transmission instruction to the wireless control unit 112 because it is a transmission operation. In this case, the telephone number of the other party input or selected by the user is temporarily stored in a predetermined area in a non-volatile memory (not shown). Then, the wireless control unit 112 that has received the instruction receives the received electric field strength of the channel ch-a read from the use state area 16 in order to confirm whether or not the service area of the channel of the provider ID currently in use is within range. Is judged whether it is higher than the specified value. In this case, the radio control unit 112 determines that the received electric field strength is high, and determines that the area is out of the service area, and the received electric field strength is low, determines that the area is out of the service area. (Steps S101 to S103 in FIG. 3).

  In step S103, since it is within the service area, the wireless control unit 112 extracts the priority order of the contract operator table 15 using the operator A as the operator ID currently in use as a key, and the extracted value is “1”. It is confirmed whether the priority is the highest by confirming whether or not. (Steps S104 and S105).

  In step S105, since the priority is “3”, which is not the highest, the wireless control unit 112 confirms whether switching to the operator ID having the highest priority is possible (selectable). . That is, the radio control unit 112 extracts the channel ch-b with the highest priority from the contractor table 15 and confirms whether the received electric field strength of the extracted channel ch-b is higher than a specified value. Confirm whether or not switching is possible with (can be selected). (Steps S106, S107).

  In step S107, since the received electric field strength is not higher than the specified value, the wireless control unit 112 checks whether or not the priority order subsequent to the priority order “1” exists in the contract operator table 15. Since it exists in this case, the wireless control unit 112 confirms whether or not switching to the next highest priority provider ID is possible (selectable). That is, the radio control unit 112 extracts the channel ch-c having the priority “2” from the contract operator table 15 and confirms whether the received electric field strength of the extracted channel ch-c is higher than the specified value. Confirm whether or not switching is possible with (can be selected). (Steps S110, S111, S107).

  In step S107, since the received electric field strength is higher than the predetermined value, the radio control unit 112 determines that switching is possible (selectable), and currently uses the channel C-c and the carrier C that is the carrier ID. It registers in the use state area 16 as a channel of the middle business. (Step S108).

  Further, the radio control unit 112 reads the channel ch-c of the operator C that is currently in use (the radio communication network of the operator C) from the use state area 16, selects the read channel ch-c, and illustrates the channel ch-c. The telephone number of the connection destination is read from the non-volatile memory that is not connected and a call connection request (transmission) is made. When a call connection is established with the other party, the radio control unit 112 displays the business operator C, which is the selected business ID (business name), on the display unit 14, and the other party that is call-connected via the wireless unit 12. Audio data is exchanged between the destination and the audio processing unit 17. (Steps S109 and S120).

  As described above, if the user sets priorities in the contract operator table 15 in advance, the control unit 11 of the mobile terminal 10 determines the channel ch− of the lowest operator A according to the priorities desired by the user. Even if a is used, and even if the operator B with the highest priority is out of the service area, the channel ch-c of the operator C with the next highest priority is selected.

  As described above, according to the embodiment of the present invention, the control unit 11 of the mobile terminal 10 sets the table 15 in which the wireless communication network provided by the business operator contracted for roaming is set for each business operator. The priority order used for each wireless communication network provided by the provider is set in the contractor trader table 15, and the wireless communication network with the highest priority set in the contractor provider table 15 at the time of outgoing call is set. In order to confirm whether the service area of the searched wireless communication network exists in the range, and in the process of confirming in order by searching the contract operator table 15, first, if it exists in the range Since a call connection request is made by selecting a wireless communication network that has been confirmed to exist, only the processing in the mobile terminal 10 is required, and the operator side needs to be changed in the current system There is no. Furthermore, the wireless communication network of the operator desired by the user himself can be selected as much as possible among the operators having the roaming contract.

  Further, according to the embodiment of the present invention, the control unit 11 of the mobile terminal 10 includes the table 15 in which the wireless communication network provided by the business operator contracted for roaming is set for each business operator in the mobile terminal 10. The priority order to be used for each wireless communication network provided by the subscriber is set in the contracted trader table 15 and the wireless communication network with the highest priority set in the contractor table 15 is sequentially searched at the time of outgoing call. If the service area of the searched wireless communication network is confirmed in order, and in the process of confirming in turn by searching the contract operator table 15, if it exists in the service area, it first exists in the service area Since the call connection request is made by selecting the wireless communication network that has been confirmed, the roaming operation is automatically switched, and the operability can be improved.

1 is a block diagram illustrating a configuration of a system according to the best mode for carrying out the present invention. FIG. 2 is a configuration schematic diagram illustrating an overview of a configuration in a contract provider table of FIG. 1. It is a flowchart which shows the operation | movement by interruption by the control part of FIG. In particular, it is a flowchart illustrating an operation in which the control unit selects a business operator with a high priority during a transmission operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mobile terminal 11 Control part 12 Radio | wireless part 13 Key input part 14 Display part 15 Contract provider table 16 Usage state area 17 Voice processing part 111 Operation control part 112 Radio | wireless control part 113 Key control part 901 Wireless network

Claims (11)

A roaming call control method in a mobile terminal contracted with a plurality of providers providing each wireless communication network,
Setting means for setting a priority order to be used for each wireless communication network provided by the operator;
Confirmation means for confirming whether or not there is an area within the order from the service area of the wireless communication network with the highest priority set by the setting means at the time of outgoing call;
Connection means for selecting a wireless communication network that is first confirmed to be in the service area and making a call connection request if it exists in the service area in the process of sequentially confirming by the confirmation means. A roaming call control method in a portable terminal. 2. The roaming call control method in a portable terminal according to claim 1, further comprising display means for displaying a name of a provider providing the wireless communication network selected by the connection means. A roaming call control method in a mobile terminal contracted with a plurality of providers providing each wireless communication network,
Setting means for setting a priority order to be used for each wireless communication network provided by the operator;
First confirmation means for confirming whether a service area of a wireless communication network currently in use exists at the time of outgoing call;
Second confirmation means for confirming whether the priority of the wireless communication network currently in use is the highest if within the range by the first confirmation means;
Third confirmation means for confirming whether or not the second confirmation means exists within a range in order from the service area of the wireless communication network having the highest priority set by the setting means if the priority is not the highest; ,
First connection means for selecting a wireless communication network that is first detected to be in the service area and making a call connection request if it exists in the service area in the process of sequentially confirming by the third confirmation means; A roaming call control method in a portable terminal. 4. The apparatus according to claim 3, further comprising second connection means for making a call connection request by selecting the wireless communication network that is currently in use if the wireless communication network that is currently in use does not exist even if the third confirmation means sequentially confirms. The roaming call control system in the portable terminal as described. 4. The roaming call control method for a portable terminal according to claim 3, further comprising display means for displaying a name of a provider providing the wireless communication network selected by the first connection means. The determination as to whether or not the wireless communication network exists within a service area is within the service area if the received electric field strength of the wireless communication network is equal to or higher than a specified value, and is out of service if it is less than the specified value. Item 5. A roaming call control method in a mobile terminal according to item 1, 3, or 4. A roaming call control method in a mobile terminal contracted with a plurality of providers providing each wireless communication network,
Prepare a table that sets the wireless communication network provided by the operator who has contracted for roaming for each operator, in its own mobile terminal,
Setting the priority to be used for each wireless communication network provided by the operator in the table;
A step of sequentially searching for a wireless communication network having the highest priority set in the table at the time of outgoing call and confirming whether or not the service area of the searched wireless communication network exists within a range;
Selecting the wireless communication network that is first confirmed to be in the service area if it exists in the service area in the process of sequentially confirming by searching the table, and performing a call connection request. A roaming call control method in a portable terminal. A roaming call control method in a mobile terminal contracted with a plurality of providers providing each wireless communication network,
Prepare a table that sets the wireless communication network provided by the operator who has contracted for roaming for each operator, in its own mobile terminal,
Setting the priority to be used for each wireless communication network provided by the operator in the table;
Confirming whether the service area of the wireless communication network currently in use exists at the time of outgoing call,
Checking whether the priority of the currently used wireless communication network is the highest if the service area of the currently used wireless communication network exists within a range; and
If the priority of the currently used wireless communication network is not the highest, the wireless communication network having the highest priority set in the table is searched in order, and the service area of the searched wireless communication network exists within the range. Step to check in order,
Selecting the wireless communication network that is first confirmed to be in the service area if it exists in the service area in the process of sequentially confirming by searching the table, and performing a call connection request. A roaming call control method in a portable terminal. 9. The call connection request is made by selecting the currently used wireless communication network if there is no existing network in the process of sequentially checking the table by searching the table. Roaming call control method in a portable terminal. 9. The roaming call control method for a mobile terminal according to claim 7, further comprising a step of displaying a name of a provider that provides a wireless communication network when the wireless communication network is selected and a call connection request is made. The determination as to whether or not the wireless communication network exists within a service area is within the service area if the received electric field strength of the wireless communication network is equal to or higher than a specified value, and is out of service if it is less than the specified value. Item 10. A roaming call control method in a portable terminal according to item 7, 8, or 9.

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