IMS User Fallback Circuit Domain Addressing Method and System

Abstract

The present invention discloses a method and system for addressing a circuit switched domain during IMS user fallback, including a processing module, which is signal-connected to the circuit switched domain, senses the registration of an IMS user in the circuit switched domain, and addresses a roaming number in the circuit switched domain; an ENUM module, which is connected to the processing module and processes queries initiated from the IMS domain. The ENUM module sends a query to the processing module and feeds back the query result. The present invention directly or indirectly senses the location update of a user in the circuit switched domain, generates and manages corresponding dynamic data for use in pre-screening when addressing a roaming number for a called party. The pre-screening query can greatly relieve the pressure on addressing a roaming number in the circuit switched domain and reduce a large number of ineffective addressings for non-fallback users.

Description

Technical Field

[0001] The present invention relates to the field of mobile communications, and particularly to an addressing method and system for IMS user fallback to the circuit domain. Background Art

[0002] In the era of 2G / 3G mobile networks, the technical routes were mainly divided into two major camps: 3GPP and 3GPP2. However, since the 4G mobile network, the 3GPP camp has occupied the main position in the market. The 4G network is a pure packet domain data network, and its voice service is carried by the IMS network, namely VoLTE, which is different from the traditional circuit domain voice service of 2G / 3G. To ensure service continuity, the networks in the 3GPP camp deploy the 4G EPC-HSS, IMS-HSS, and 2G / 3G HLR in a combined manner. While the networks in the 3GPP2 camp can only achieve the combined deployment of the 4G EPC-HSS and IMS-HSS, and the HLR and HSS are deployed separately.

[0003] For the networks with separate HLR / HSS deployments, 4G users still have the need to fallback to the 2G / 3G circuit domain, such as for international roaming. The existing international roaming implementation methods are as attached Figure 1 ... Among them, the GC gateway is a special network element that acts as both the HLR role in the overseas 3GPP (GMS / WCDMA) network and the VLR role in the 3GPP2 (CDMA) network, and realizes the conversion of different mobile network MAP protocols. The 3GPP2 camp urgently needs to retire the original 3GPP2 (CDMA) network, and there is also a need for roaming with overseas 3GPP (GMS / WCDMA) networks. The prerequisite for retiring the domestic CDMA network is to decouple from international roaming. International roaming has its own independent HLR. To solve the problem of addressing the roaming number for the called voice service, the original IMS gateway MSCF needs to be transformed into a GMSC that supports the GSM / WCDMA MAP protocol. The difficulty lies in that during the coexistence of different network HLRs, it is impossible for the GMSC to select which MAP protocol to address the HLRs of different domestic or overseas networks according to a single number at the same time. Summary of the Invention

[0004] The purpose of the present invention is to provide an addressing method and system for IMS user fallback to the circuit domain, which can directly complete the addressing of the circuit domain roaming number for the called fallback user within the IMS domain based on the IMS call signaling process without modifying the existing circuit domain network.

[0005] To solve the above technical problems, the present invention provides an addressing system for IMS user fallback to the circuit domain, including:

[0006] A processing module, which is signal-connected to the circuit domain, senses the registration of IMS users in the circuit domain, and addresses the roaming number in the circuit domain;

[0007] The ENUM module is connected to the processing module and processes queries initiated from the IMS domain. The ENUM module sends queries to the processing module and feeds back query results.

[0008] Furthermore, in the addressing system for IMS user fallback to the circuit domain, there is also a database module connected to the processing module and the ENUM module. The database module is used to store and manage static data and dynamic data of circuit domain-registered users.

[0009] Furthermore, in the addressing system for IMS user fallback to the circuit domain, the processing module senses location updates from the circuit domain, and the database module updates the stored user registration status according to the location update message from the processing module.

[0010] Furthermore, in the addressing system for IMS user fallback to the circuit domain, the static data includes the circuit domain MSISDN and IMSI of all IMS users; the dynamic data includes the data formed after the creation, change, or deletion of interface messages between the processing module and the database module, and also includes the circuit domain registration status, location information, and registration validity period.

[0011] Furthermore, in the addressing system for IMS user fallback to the circuit domain, the processing module is a MAP message processing module.

[0012] In addition, on the other hand of the present invention, an addressing method for IMS user fallback to the circuit domain is also proposed. Using any one of the systems described above, the method includes:

[0013] The ENUM module receives a query request initiated from the IMS domain, forwards the query request to the processing module, and the processing module initiates roaming number addressing to the circuit domain and feeds back the query result.

[0014] Furthermore, in the addressing method for IMS user fallback to the circuit domain, the system includes a database module connected to the processing module and the ENUM module. The database module is used to store and manage static data and dynamic data of circuit domain-registered users; wherein, the method includes:

[0015] The processing module senses location updates from the circuit domain and sends the location update message to the database module;

[0016] The database module generates and manages dynamic data according to the location update message.

[0017] Furthermore, in the addressing method for IMS user fallback to the circuit domain, the location update message includes initial location update, periodic location update, and deregistration.

[0018] Further, in the addressing method for IMS user fallback to the circuit domain, the system includes a database module, a connection processing module, and an ENUM module. The database module is used to process the pre-screening request initiated by the ENUM module. Among them, the method includes:

[0019] When the ENUM module receives a query request initiated from the IMS domain, it first requests pre-screening from the database module.

[0020] The ENUM module forwards the query request to the processing module as needed according to the pre-screening result, and the processing module initiates roaming number addressing to the circuit domain.

[0021] Further, in the addressing method for IMS user fallback to the circuit domain, the pre-screening includes the steps of:

[0022] When the database module receives the query request initiated by the ENUM module, if the user is in a registered state and within the validity period, it returns the IMSI and location information of the number; if the user is in an unregistered state, or exceeds the registration validity period, or has no dynamic data, it returns a failure error code.

[0023] Further, in the addressing method for IMS user fallback to the circuit domain, the processing module senses the registration of the IMS user in the circuit domain in a direct sensing manner. The direct sensing manner is that the processing module acts as an HLR in the circuit domain and senses the registration status of the IMS user in the circuit domain by receiving the location update message initiated by the terminal in the circuit domain.

[0024] Further, in the addressing method for IMS user fallback to the circuit domain, the processing module senses the registration of the IMS user in the circuit domain in an indirect sensing manner. The indirect sensing manner is that the processing module acts as a GMSC in the circuit domain, and the signaling monitoring system detects the location update event initiated by the terminal in the circuit domain and notifies the processing module, thereby sensing the registration status of the IMS user in the circuit domain.

[0025] Further, in the addressing method for IMS user fallback to the circuit domain, the steps for addressing the roaming number in the circuit domain include:

[0026] After receiving the roaming number addressing request initiated by the ENUM module, use the direct addressing method or the indirect addressing method to address the roaming number in the circuit domain.

[0027] The direct addressing method is that the processing module directly addresses the VLR where the user is registered through the signaling network to obtain the roaming number.

[0028] The indirect addressing mode is that the processing module initiates addressing to the HLR to which the user belongs through the signaling network, and the HLR addresses the VLR to obtain the roaming number;

[0029] The roaming number or a failure result is returned.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] Compared with the current 3GPP2 network, the present invention does not need to transform the existing circuit domain network. Based on the IMS call signaling process, the circuit domain roaming number addressing of the called fallback user is directly completed within the IMS domain.

[0032] Furthermore, the present invention directly or indirectly senses the location update of the user in the circuit domain, generates and manages corresponding dynamic data for pre-screening purposes when the called party addresses the roaming number. The pre-screening query can greatly reduce the pressure on the circuit domain to address the roaming number and reduce a large number of ineffective addressings for non-fallback users. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural block diagram of the international roaming implementation method in the prior art;

[0034] Figure 2 It is a block diagram of the addressing system for the IMS user to fallback to the circuit domain in the first embodiment of the present invention;

[0035] Figure 3 It is a logic block diagram of the circuit domain location update processing in the second embodiment of the present invention;

[0036] Figure 4 It is a logic block diagram of the called party query processing for pre-screening without registration information in the second embodiment of the present invention;

[0037] Figure 5 It is a logic block diagram of the called party query processing for pre-screening with registration information when the circuit domain does not return the roaming number in the second embodiment of the present invention;

[0038] Figure 6 It is a logic block diagram of the called party query processing for pre-screening with registration information when the circuit domain returns the roaming number in the second embodiment of the present invention;

[0039] Figure 7 It is a logic block diagram of the static data update processing in the second embodiment of the present invention;

[0040] Figure 8 It is a logic block diagram of the dynamic data update processing in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The addressing method and system for IMS user fallback to the circuit domain of the present invention will be described in more detail below in conjunction with the schematic diagrams. The preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as broad knowledge for those skilled in the art and not as a limitation to the present invention.

[0042] In the following paragraphs, the present invention will be described more specifically by way of example with reference to the accompanying drawings. The advantages and features of the present invention will be more clear according to the following description and the claims. It should be noted that the drawings are all in a very simplified form and use non-precise scales, only for the purpose of conveniently and clearly assisting in explaining the objectives of the embodiments of the present invention.

[0043] Embodiment 1

[0044] As Figure 2 shown, an addressing system for IMS user fallback to the circuit domain according to an embodiment of the present invention includes: a processing module, signal-connected to the circuit domain, sensing the registration of an IMS user in the circuit domain and addressing a roaming number in the circuit domain; an ENUM module, connected to the processing module and processing queries initiated from the IMS domain, the ENUM module sending a query to the processing module and feeding back the query result.

[0045] Preferably, in this embodiment, the addressing system further includes a database module, connected to the processing module and the ENUM module, the database module being used to store and manage static data and dynamic data of users registered in the circuit domain.

[0046] Among them, the processing module is a MAP message processing module. The processing module senses a location update from the circuit domain, and the database module updates the stored user registration status according to the location update message from the processing module.

[0047] In this embodiment, the processing module can directly or indirectly sense the registration of an IMS user in the circuit domain.

[0048] In a specific embodiment, a direct sensing method can be adopted. The processing module acts as an HLR in the circuit domain and senses the registration status of an IMS user in the circuit domain by receiving location update messages initiated by the terminal in the circuit domain, including initial location update, periodic location update, deregistration, etc.

[0049] In other embodiments other than this embodiment, an indirect sensing method can also be adopted. The processing module acts as a GMSC in the circuit domain, and a signaling monitoring system detects location update events initiated by the terminal in the circuit domain, including initial location update, periodic location update, deregistration, etc., and notifies the processing module, thereby sensing the registration status of an IMS user in the circuit domain.

[0050] In this embodiment, the processing module also needs to process the circuit domain addressing roaming number. After receiving the roaming number addressing request initiated by the ENUM module, it directly or indirectly addresses the roaming number in the circuit domain and returns the roaming number or other failure results.

[0051] In a specific embodiment, a direct addressing method can be adopted. The processing module directly addresses the VLR registered by the user through the signaling network to obtain the roaming number.

[0052] In other embodiments other than this embodiment, an indirect addressing method can be adopted. The processing module addresses the HLR to which the user belongs through the signaling network. The HLR addresses the VLR to obtain the roaming number and returns the roaming number or other failure results to the ENUM module.

[0053] In addition, in this embodiment, the processing module can also update the user registration status.

[0054] In a specific embodiment, the processing module senses the registration status of the IMS user in the circuit domain and updates the registration status of this user to the database module, including creating, changing, and deleting user data. The processing module addresses the roaming number in the circuit domain. If the roaming number is not obtained, it is a failure result, and the processing module updates the registration status of this user to the database module and deletes the user data.

[0055] In this embodiment, the database module is used to store the static data and dynamic data of the users registered in the circuit domain.

[0056] Specifically, the database module implements static data management. The static data includes but is not limited to the circuit domain MSISDN and IMSI of all IMS users. When an IMS user opens an account, closes an account, or changes a card through the CRM, the CRM needs to synchronously update the MSISDN and IMSI of the IMS user to the database module. The database module always stores the latest paired MSISDN and IMSI of all IMS users. In addition, the database module implements dynamic data management. The dynamic data is created, changed, and deleted by the interface messages between the processing module and the database module, and also includes the circuit domain registration status, location information, registration validity period, etc., which are the dynamic data generated during the registration of IMS users in the circuit domain.

[0057] In this embodiment, the database module can also perform pre-screening on the circuit domain addressing roaming number.

[0058] In a specific embodiment, when the database module receives the query initiated by the ENUM module, if the user is in the registered state and within the validity period, it returns the IMSI and location information of this number

[0059] In other embodiments other than this embodiment, when the database module receives a query initiated by the ENUM module, if the user is in an unregistered state, or has exceeded the registration validity period, or has no dynamic data, it returns a failure error code.

[0060] In this embodiment, the ENUM module is used to process queries initiated by the IMS domain and return a circuit domain roaming number or a failure response.

[0061] In a specific embodiment, the ENUM module is used to process NAPTR query requests. When the ENUM module receives a NAPTR query containing the MSISDN mobile number initiated by the IMS domain, it returns a sipurl with a circuit domain roaming number or returns a "no such name" error code according to the query result sent to the processing template or the database module.

[0062] In this embodiment, the ENUM module performs pre-screening on the circuit domain addressing roaming number.

[0063] In a specific embodiment, the ENUM module sends a pre-screening query request containing the MSISDN mobile number to the database module. If the number is in a registered state, it receives a response containing the IMSI and location information of the number.

[0064] In other embodiments other than this embodiment, when the ENUM module sends a pre-screening query request containing the MSISDN mobile number to the database module, if the number is in an unregistered state, it receives a failure error code.

[0065] Further, the ENUM module addresses the circuit domain roaming number. The ENUM module sends an addressing roaming number request to the processing template according to the pre-screening result. The processing template executes the circuit domain addressing roaming number function and returns a roaming number or other failure results to the ENUM module.

[0066] Embodiment 2

[0067] This embodiment proposes an addressing method for IMS user fallback to the circuit domain, using the addressing system for IMS user fallback to the circuit domain as described in Embodiment 1. Among them, the method includes:

[0068] The ENUM module receives a query request initiated by the IMS domain and forwards the query request to the processing module, and the processing module initiates a roaming number addressing to the circuit domain.

[0069] Further, the method further includes:

[0070] The processing module senses location update from the circuit domain and sends a location update message to the database module;

[0071] The database module generates and manages dynamic data according to the location update message;

[0072] When the ENUM module receives a query request initiated by the IMS domain, it first requests a pre-screening from the database module;

[0073] The ENUM module forwards the query request to the processing module as needed according to the pre-screening result, and the processing module initiates roaming number addressing to the circuit domain.

[0074] In a specific embodiment, please refer to Figure 3 The IMS user falls back to the circuit breaker domain to initiate location update, which includes the following steps:

[0075] 1. The circuit domain directly sends the location update message to the processing module through the No. 7 signaling network, and the processing module executes the HLR function and accepts the location update; or the signaling monitoring system detects a successful circuit domain location update message, generates a location update event and pushes it to the processing module of the present invention.

[0076] 2. The processing module senses the location update and updates the dynamic data generated by the circuit domain location update to the database module, including the user's public identifier MSISDN, private identifier IMSI, registration status, location information of the visited location, registration validity period, etc. Among them: initial registration corresponds to creating dynamic data, re-registration corresponds to changing dynamic data, and cancellation corresponds to deleting dynamic data.

[0077] IMS users do called pre-screening without registration information, see Figure 4 .

[0078] 1. When the user is called, the IMS network element initiates a NAPTR query. The query object includes the direct MSISDN number or the indirect prefix + MSISDN number.

[0079] 2. The NAPTR query is recursively sent to the ENUM module of the present invention. The ENUM module extracts the MSISDN number and initiates a query to the database module to obtain the user's registration status and current location information.

[0080] 3. The database module does not have dynamic data corresponding to the MSISDN and returns a failure error code.

[0081] 4. After receiving the failure error code returned by the database module, the ENUM module directly returns a failure response including but not limited to a "no such name" error code for the NAPTR query.

[0082] When an IMS user is called, pre-screening shows registration information, but the circuit domain does not return a roaming number. For the query processing logic, see Figure 5 .

[0083] 1. When the user is called, the IMS network element initiates a NAPTR query. The query objects include the direct MSISDN number or the indirect prefix + MSISDN number.

[0084] 2. This NAPTR query is recursively sent to the ENUM module. The ENUM module extracts the MSISDN number and initiates a query to the database module to obtain the user's registration status and current visited location information.

[0085] 3. The database module queries the dynamic data corresponding to the MSISDN and returns a successful response carrying the private identifier IMSI, visited location information VLR Number or GT.

[0086] 4. After receiving the successful response returned by the database module, the ENUM module initiates a roaming number addressing query request to the processing module, carrying the public identifier MSISDN, private identifier IMSI, visited location information VLR Number or GT.

[0087] 5. The processing module initiates roaming number addressing to the circuit domain through the Signaling System No. 7 network.

[0088] 6. When the processing module receives an error code returned by the circuit domain or does not receive a roaming number, it returns a failure error code to the ENUM module; at the same time, it deletes the dynamic data of this MSISDN from the database module.

[0089] 7. After receiving the failure error code returned by the processing module, for the NAPTR query, the ENUM module returns a failure response including, but not limited to, the "no such name" error code.

[0090] When an IMS user is called, pre-screening shows registration information, and the circuit domain returns a roaming number. For the query processing logic, see Figure 6 .

[0091] 1. When the user is called, the IMS network element initiates a NAPTR query. The query objects include the direct MSISDN number or the indirect prefix + MSISDN number.

[0092] 2. This NAPTR query is recursively sent to the ENUM module. The ENUM module extracts the MSISDN number and initiates a query to the database module to obtain the user's registration status and current visited location information.

[0093] 3. The database module queries the dynamic data corresponding to the MSISDN and returns a success response carrying the private identifier IMSI and the visited location information VLR Number or GT.

[0094] 4. After receiving the successful response returned by the database module, the ENUM module initiates a roaming number addressing query request to the processing module, carrying the public identifier MSISDN, the private identifier IMSI, and the visited location information VLR Number or GT.

[0095] 5. The processing module initiates roaming number addressing to the circuit domain through the No. 7 signaling network.

[0096] 6. The processing module receives the roaming number returned by the circuit domain, and returns a success response carrying the roaming number to the ENUM module.

[0097] 7. After receiving the successful response returned by the processing module, the ENUM module returns a successful response carrying the roaming number for the NAPTR query, wherein the domain name of the sip url is the circuit domain name.

[0098] For static data processing logic, see Figure 6 .

[0099] When an IMS user opens an account, cancels an account, or changes a card through CRM, CRM or the service opening system synchronously updates the public identifier MSISDN and private identifier IMSI of the IMS user to the database module.

[0100] Dynamic data processing logic see Figure 7 .

[0101] The processing module senses the user's location update in the circuit domain based on the location update message received by the No. 7 signaling network or the location update event pushed by the signaling monitoring system, and updates the dynamic data of the user to the database module.

[0102] The processing module fails to address the roaming number in the circuit domain and fails to obtain the roaming number, and deletes the dynamic data of the user from the database module.

[0103] In summary, the present invention adopts the idea and method of connecting the IMS network NAPTR query with the circuit domain addressing roaming number. Based on the NAPTR query, the circuit domain roaming number can be directly returned for the circuit domain called user. Based on the dynamic database updated by the circuit domain location, the pre-screening basis is provided for the IMS network NAPTR query, and the differentiated query results are returned.

[0104] For the mobile network of the original 3GPP2 camp, its network does not require major transformation, which solves the problem of voice call addressing for IMS users falling back to the 3GPP2 G / 3G circuit domain.

[0105] The most important step in the IMS network call process is to initiate a NAPTR query to ENUM, which translates the called number from the tel url format to the sip url format and is an essential link for each call. From the perspective of the IMS network, the present invention is a general NAPTR query and is a standard call processing flow of the IMS network, without the need for modification of the IMS network.

[0106] The present invention directly or indirectly senses the location update of the user in the circuit domain, generates and manages the corresponding dynamic data for use in pre-screening when addressing the roaming number of the called party. The pre-screening query can greatly reduce the pressure on the circuit domain addressing roaming number and reduce a large number of invalid addressings for non-fallback users.

[0107] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. An addressing system for IMS user fallback to the circuit domain, characterized in that including: A processing module, connected to a circuit domain signal, senses the IMS user's registration in the circuit domain, and addresses the roaming number in the circuit domain; An ENUM module, connected to the processing module, and processes queries initiated from the IMS domain. The ENUM module sends a query to the processing module and feeds back the query result; A database module, connected to the processing module and the ENUM module, is used to process the pre-screening request initiated by the ENUM module; When the ENUM module receives a query request initiated from the IMS domain, the ENUM module first requests pre-screening from the database module; The ENUM module forwards the query request to the processing module as needed according to the pre-screening result, and the processing module initiates roaming number addressing to the circuit domain; wherein, the pre-screening includes: When the database module receives the query request initiated by the ENUM module, if the user is in a registered state and within the validity period, it returns the IMSI and location information of the number; if the user is in an unregistered state, or exceeds the registration validity period, or has no dynamic data, it returns a failure error code.

2. The addressing system for IMS user fallback to the circuit domain according to claim 1, wherein the processing module senses location updates from the circuit domain, and the database module updates the stored user registration status according to the location update message from the processing module.

3. The addressing system for IMS user fallback to the circuit domain according to claim 1, wherein the database module is further used to store and manage the static data and dynamic data of circuit domain registered users; wherein, the static data includes the circuit domain MSISDN and IMSI of all IMS users; the dynamic data includes the data formed after the creation, change or deletion of the interface message between the processing module and the database module, and also includes the circuit domain registration status, location information and registration validity period.

4. The addressing system for IMS user fallback to the circuit domain according to claim 1, characterized in that, The processing module is a MAP message processing module.

5. An addressing method for IMS user fallback to the circuit domain, adopting any one of the systems described in claims 1 to 4, characterized in that, The method includes: The ENUM module receives a query request initiated from the IMS domain, forwards the query request to the processing module, and the processing module initiates roaming number addressing to the circuit domain and feeds back the query result.

6. The addressing method for IMS user fallback to the circuit domain according to claim 5, characterized in that, The database module is used to store and manage the static data and dynamic data of circuit domain registered users; wherein, the method includes: The processing module senses location updates from the circuit domain and sends the location update message to the database module; The database module generates and manages dynamic data according to the location update message.

7. The addressing method for IMS user fallback to the circuit domain according to claim 6, characterized in that, The location update message includes initial location update, periodic location update and deregistration.

8. The addressing method for circuit switched fallback of IMS users as described in claim 5, characterized in that, The database module is used to process the pre-screening request initiated by the ENUM module; wherein, the method includes: When the ENUM module receives a query request initiated from the IMS domain, it first requests pre-screening from the database module; The ENUM module forwards the query request to the processing module as needed according to the pre-screening result, and the processing module initiates roaming number addressing to the circuit domain.

9. The addressing method for IMS user fallback to the circuit domain according to claim 8, characterized in that, The pre-screening includes the steps: When the database module receives the query request initiated by the ENUM module, if the user is in the registered state and within the validity period, it returns the IMSI and location information of the number; if the user is in the unregistered state, or exceeds the registration validity period, or has no dynamic data, it returns a failure error code.

10. The addressing method for IMS user fallback to the circuit domain according to claim 5, characterized in that, The processing module senses the IMS user's registration in the circuit domain in a direct sensing manner; the direct sensing manner is that the processing module acts as an HLR in the circuit domain, and senses the registration state of the IMS user in the circuit domain by receiving the location update message initiated by the terminal in the circuit domain.

11. The addressing method for IMS user fallback to the circuit domain according to claim 5, characterized in that, The processing module senses the IMS user's registration in the circuit domain in an indirect sensing manner; the indirect sensing manner is that the processing module acts as a GMSC in the circuit domain, and the signaling monitoring system detects the location update event initiated by the terminal in the circuit domain and notifies the processing module, thereby sensing the registration state of the IMS user in the circuit domain.

12. The addressing method for IMS user fallback to the circuit domain according to claim 5, characterized in that, Addressing the roaming number in the circuit domain includes the steps of: After receiving the roaming number addressing request initiated by the ENUM module, address the roaming number in the circuit domain using the direct addressing method or the indirect addressing method; The direct addressing method is that the processing module directly addresses the VLR registered by the user through the signaling network to obtain the roaming number; The indirect addressing method is that the processing module addresses the HLR to which the user belongs through the signaling network, and the HLR addresses the VLR to obtain the roaming number; Return the roaming number or a failure result.

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