CN107135480B

CN107135480B - Service anchoring method based on specific area

Info

Publication number: CN107135480B
Application number: CN201710305753.7A
Authority: CN
Inventors: 李赓; 吴楠; 苏玉娜; 王小旗; 许春梅
Original assignee: Henan University of Technology
Current assignee: Henan University of Technology
Priority date: 2017-05-03
Filing date: 2017-05-03
Publication date: 2020-03-31
Anticipated expiration: 2037-05-03
Also published as: CN107135480A

Abstract

The invention discloses a service anchoring method based on a specific area, which enables a VoWiFi user to anchor a service from a circuit domain to an IMS domain only in a specific access area by changing the existing flow triggered by SCP (service control point) anchoring of the circuit domain, finds a balance point in call completing rate and continuing delay, improves the completing rate in a weak coverage area, avoids performing service anchoring processing in all access areas after anchoring service is started, ensures that the continuing delay of other coverage areas cannot be increased, and has good service experience.

Description

Service anchoring method based on specific area

Technical Field

The invention relates to the technical field of communication, in particular to a service anchoring method based on a specific area.

Background

And (3) common number:

the common number is that when an operator has multiple mobile core networks (CS, PS or IMS), the same set of code number resources are shared, and users under different networks can log in and reside in the multiple mobile core networks simultaneously or respectively using the same code number. In view of compatibility with existing code number resources, the shared code number resources are usually in the form of e.164 format code numbers of conventional mobile numbers. The common number can not only solve the problem of shortage of number resources of operators, but also reserve the number of the user, thereby providing good experience for the user.

Concept of TA and LA

The 2G/3G/4G identifies the relevant concepts of the user's location as shown in Table 1:

TABLE 1

LA	Location Area	Location area
			RA	Routing Area	Routing area
LAI	LA Identity	Location area identification
			RAI	RA Identity	Routing area identification
TAI	TA Identity	Tracking area identification
			LAC	LA Code	Location area coding
RAC	RA Code	Routing area coding
			TAC	TA Code	Tracking area coding

LA (location area: LAI ═ PLMN + LAC) is a concept of circuit domain in 2G and 3G times, which enables a mobile switching exchange (MSC/server) to know the location of a terminal in time, and when paging a terminal, a mobile switching center searches for all cells in the location area of the terminal. The terminal does not need position updating in a position area; when moving across LA, LA updating process needs to be initiated so that the network knows the location area of the terminal; meanwhile, the terminal needs a periodic LA update procedure in order to keep close contact with the network side.

RA (routing area: RAI ═ PLMN + LAC + RAC) is a concept of packet domains in the 2G era and the 3G era, which enables the SGSN to know the location of the terminal in time, and before the terminal initiates data transmission, the terminal must register with the SGSN and the HLR and page the terminal in the routing area. The terminal can not need to do RA updating in an RA; RA updates will occur when moving across routing areas; with periodic RA updates.

The TA, Tracking Area (Tracking Area), is a concept newly set up by the LTE system for location management of the UE. When the UE is in the idle state, the core network can know the tracking area where the UE is located, and when the UE in the idle state needs to be paged, paging must be performed in all cells of the tracking area where the UE is registered.

The TAI is Tracking Area Identity (Tracking Area Identity) of LTE, and is composed of PLMN and TAC. A plurality of TAs form a TA list and are simultaneously allocated to a UE, and the UE does not need to perform TA update when moving in the TA list (taist) to reduce frequent interaction with the network; when the UE enters a new TA area that is not in the TA list registered by the UE, TA update needs to be performed, the MME reallocates a group of TAs to the UE, and the newly allocated TAs may also include some TAs in the original TA list; each cell belongs to only one TA. The TA is a configuration at a cell level, multiple cells may configure the same TA, and one cell may belong to only one TA.

Concept of WiFi

As a wireless broadband access mode, the WLAN has the advantages of high access bandwidth, low cost, high terminal popularity, and the like, but also has the weaknesses of small coverage area, poor mobility, and the like; the WLAN is used for hot spot coverage, the data rate is high, the popularity of the terminal is high, and the used frequency band is mainly an unauthorized frequency band without application. However, it also has disadvantages, such as less frequency point resources, frequency bands susceptible to interference, high frequency band, weak continuous coverage capability, low efficiency of air interface protocol, and weak capability of multi-user access. The QoS guarantee capability of the service is weak and the service is easy to attack. The 2G/3G/4G technology has great advantages in coverage and mobility, but has limited bandwidth resources. Therefore, the WLAN technology and the wireless technology can well achieve complementary advantages, and the convergence of the two is considered by many operators as one of the inevitable trends of the development of wireless data services.

Currently, the industry is still positioning WLANs mainly in data services, mainly as an important complement to mobile cellular system networks, and has not been considered as a mainstream solution for voice services indoor coverage. The IMS domain is independent from the access system, the WLAN can be used as a parallel access system to provide IMS services for users, including services such as voice services provided by IMS, and the like, and can use unified authentication and charging. The voice service solution scheme based on IMS and accessed through WLAN can solve the problem of indoor distribution of operators well, and can provide more efficient voice service quality through lower cost.

VoWiFi Room Split coverage requirement

With the gradual maturity of the VoLTE service, the terminal itself has the capability of VoIP, and meanwhile, the mainstream terminals in the industry also support the WiFi function, and the fact that the packet voice service that uses IMS to complete WiFi access also becomes a rational chapter makes full use of WiFi to solve the problem of voice service room coverage after LTE deployment, which is urgently needed to be considered by operators.

At present, if the voice service of the VoIP is developed and popularized in a large area, the risk in the aspects of policy and telecommunication regulation is faced, the VoIP service is limited in a certain effective range, and the risk can be avoided.

Based on the above two requirements, WiFi is used to solve the problem of operator indoor coverage, and provide voice services limited to the home broadband range, which becomes the first choice, so we need to solve how to use the broadband access network to limit the user who opens WiFi voice services to the home range, solve the problem of operator coverage, and provide preferential voice telephone services to the user, so that the operator and the user achieve the win-win purpose.

Consideration of mobile terminal access scenarios

From the access point of view, different accesses of operators can be firstly divided into a fixed access and a mobile access.

1) The fixed access mainly refers to accessing to an operator network through devices such as ASDL and PON.

2) Wherein mobile access mainly refers to passing through 2G, 3G, 4G, WiFi and other networks.

The WiFi access scene is special, on one hand, the access can be realized through the GGSN/PGW of the mobile network, and on the other hand, the access can also be realized through the WiFi AP hot spot assumed by the fixed network.

Due to the particularity of the mobile terminal, it is impossible to access directly through the network cable of the fixed network or the telephone twisted pair, so that the access network of the mobile terminal is mainly accessed through a cellular network such as 2G, 3G and 4G and a wireless local area network such as WLAN. Unified cooperative management of the four major network access technologies of 2G/3G/4G/WLAN is also often referred to as four-network cooperation within the operator.

Concept of SCC AS

SCC AS, which is called Service centralized and Continuity application server, is an IMS application server in a home network, and inserts the Service server into a session path through iFC trigger rules in a calling or called flow, and usually, when SCC AS is triggered, the SCC AS is located in a first AS in the calling path or a last AS in the called path, and mainly completes functions such AS traffic transfer and domain selection.

In the aspect of terminal call Domain Selection, the SCC-AS has the capability of accessing Domain Selection, i.e. T-ADS (terminal access Domain Selection), i.e. it can cooperate with the HSS to indirectly access the SGSN/MME, thereby determining the network where the user currently logs in, and thus completing the Domain Selection work of service and access.

In addition, in the GSMA standard, in order to trigger SCC-AS to perform service processing and judgment, a user may sign a special intelligent network service, the SCP function is built in the SCC-AS, that is, the SCC-AS supports a CAP interface to the MSC, and the function completes the anchoring process from the circuit domain to the IMS domain.

Introduction to user anchoring procedure

From the development of the network, the IMS and the mobile network soft switch still keep the interworking and coexistence relationship for a long time, the soft switch evolves to ICS (IMS Centralized Services, IMS Centralized service), and a certain time is needed for the IMS to uniformly control, so that the user voice service is responsible for the IMS on the LTE network and is responsible for the circuit domain soft switch network on the 2G/3G network at the stage of Pre-ICS (before IMS Centralized service).

The following concrete analysis is that the VoWiFi user adopts the scene requirement under the common number mode:

1) for a calling user, the terminal can directly select different core domains to process under different networks, so that the core network is not influenced;

2) for the called user, the voice service can be attached to the circuit domain and provided by the circuit domain, or can be registered in the IMS network, and the service provided by the IMS network is accessed through the packet domain, so that there is a case that voice answers multiple channels, and a network element needs to have a terminating domain selection function to select which domain route to establish a session with the called user.

Therefore, for VoLTE users, in the scenario of using the same user code number resource, it is necessary to ensure that the user can listen to the phone within the coverage of the mobile cellular signal without being aware of the currently attached network (2G, 3G or LTE).

In order to solve the problem of called domain selection, the standard introduces the concept of SCC-AS (see the first part), and fig. 1 is a scene diagram of the ir.64 standard specification issued by GSMA, which is a scene of the Pre-ICS stage in the scene, that is, an MSC is deployed, but the MSC does not upgrade and support the ICS function.

The prior art is based on the networking structure, and in the prior art, a routing bypass problem exists for a large number of current network users.

In order to provide the VoWiFi service, a user who opens the VoWiFi service must be anchored to the IMS domain when the user is called, that is, the domain selection of the called user needs to be anchored as a premise, and the anchoring scheme is technically characterized by the existence of a roundabout route, so that the problem needs to be solved.

Before implementing the VoWiFi scheme, the scenario and user experience are as follows:

no or weak coverage area: the signal is weak or no signal, the call completing rate is low, and call loss exists;

good coverage area: good signal and normal call completing rate.

After the VoWiFi scheme is implemented, an anchoring technology needs to be introduced, and the scene and user experience are as follows:

weak coverage area: the signal is weak, no signal exists, the IMS is accessed to provide service through WiFi, the voice call-on rate is improved, but the call connection time delay is increased in an anchoring mode;

good coverage area: the signal is good, the call completing rate is normal, and the call continuing time delay is increased due to the anchoring process of the VoWiFi service.

It can be seen that, although the problem of low call completing rate in weak or no coverage area in less specific scenes is solved by the VoWiFi at the cost of increasing the connection delay, the problem of increased connection delay in other scenes, that is, in a large number of good coverage areas of the existing network, is increased (due to the problem of activating the VoWiFi service and natural called anchoring); therefore, a need exists for a solution and a lift.

The existing network solves the problem of weak coverage or no coverage, which is usually completed by adding a base station and an indoor distribution system, but the investment cost is higher, and the problem of home coverage cannot be well solved (an indoor distribution system cannot enter home generally), after the VoWiFi technology appears, a user is allowed to access a wifi network of the home through a mobile phone, and then access an operator core network to complete the call of voice service. There is no impact on the calling service, but there is currently no technology to configure domain selection for different areas for the called service.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a service anchoring method based on a specific area, which enables a user to anchor a service from a circuit domain to an IMS domain only in a specific access area by changing the prior flow triggered by SCP (service control point) anchoring of the circuit domain, finds a balance point in the call completing rate and the connection delay, improves the completing rate in a weak coverage area, avoids performing service anchoring treatment in all access areas after anchoring service is started, ensures that the connection delay of other areas with good coverage cannot be increased, and improves the service experience of the user.

In order to achieve the purpose, the invention adopts the following technical scheme:

a service anchoring method based on a specific area comprises the following steps:

s1, the operator pre-defines a weak coverage or no coverage area information list;

s2, when the terminal installed with VoWiFi APP software logs in for the first time, the area information list is obtained, after the registration of the IMS network is successfully carried out through the VoWiFi network, the terminal regularly compares the current actual position information of the user with the area information list to judge whether the current user is located in a weak coverage area or an uncovered area, and the information of the configuration server and the HLR/HSS database about whether the user is located in the weak coverage area or the uncovered area at present is synchronously updated;

s3, when calling service occurs, the calling user sends voice service to the called user, sends IAM message to the calling MSC served by the calling user, after receiving the calling request, the calling MSC will obtain GT routing information according to the number of the called user, and sends SRI message to HLR/HSS database where the called user is located;

s4 after the HLR/HSS database of the called user receives the SRI message, the following judgment is executed:

1) if the called user is found not to sign the anchoring SCP service, executing normal routing operation for acquiring the called roaming number, and if the called user signs other intelligent network services, executing corresponding intelligent network flow;

2) if the called user is found to sign the anchor SCP service and the position of the called user is not in the weak coverage or no coverage area, the user is not anchored to the IMS, and the following operations are performed according to the situation:

2.1) if the user has no registration information in the IMS-HSS and the HLR, returning a prompt message;

2.2) if the user has registration information in HLR, executing normal signaling flow for acquiring the route;

2.3) if the user has registration information in IMS-HSS and no registration information in HLR, it indicates possible to log in by VoWiFi, and the operator processes according to the policy: when the VoWiFi service is not allowed to be used under the condition of good signal coverage, which means that the connection in a VoWiFi mode is not allowed when the called party is called, the called party is not anchored to the IMS domain, and a normal signaling flow for acquiring the route is executed;

3) if the called user signs the contract to anchor the SCP service and the current position is also in the weak coverage area or the no coverage area, the HLR/HSS database of the called user anchors the user to the IMS, and the VoWiFi APP answers the call, and the following operations are performed according to the situation:

3.1) the called user has no registration information in the IMS-HSS and HLR registration, and then the prompt information is returned;

3.2) the called user has no registration information in IMS-HSS, but has registration information in HLR, although the signal is not good, the mobile phone is not turned off, the circuit domain call is still allowed, or prompt information is sent to the called user to prompt the called user to log in APP to call back the calling user;

3.3) the called user has registered the IMS-HSS, then anchored to the IMS domain, and the call is connected through VoWiFi APP.

Further, in step S1, the operator dynamically updates the area information list.

Further, step S2 is specifically as follows:

s2.1, when a terminal logs in for the first time, a request is sent to a configuration server, the request message carries the current position information of a user, and after the configuration server receives the request, the relevant information of the user is sent to the terminal, wherein the relevant information comprises the configuration information of an IMS access point (SBC) and the area information list;

s2.2, after the terminal obtains the relevant information sent by the configuration server, the IMS network is registered through the VoWiFi network; the configuration server inquires whether the current position information of the user is in a weak coverage area or a non-coverage area and sends a corresponding result and the user information to an HLR/HSS database; after receiving the message sent by the configuration server, the HLR/HSS database sets the relevant information of the database;

s2.3, the terminal regularly acquires the actual position information of the user, compares the actual position information with the area list information, judges whether the actual position information is in a weak coverage area or a non-coverage area, and conducts keep-alive treatment on the configuration server;

s2.4, when the configuration server finds that the comparison result between the current actual position information of the user and the area list information changes after receiving the message, the configuration server initiates a request for updating the data of the HLR/HSS database and sends a message about the comparison result between the latest current actual position information of the user and the area list information to the HLR/HSS database; and after receiving the message, the HLR/HSS database updates the related information.

Further, in step S4, the specific method of the keep-alive processing is:

the terminal judges that the current actual position of the user is in a weak coverage or non-coverage area, and the last reported message is in the weak coverage or non-coverage area, the current report is not carried out, if the last reported message is judged to be not in the weak coverage or non-coverage area or not, the message of the position information of the user in the weak coverage or non-coverage area is reported to a configuration server;

the terminal judges that the current actual position information of the user is not in the area with weak coverage or no coverage, and the last reported message is the message not in the area with weak coverage or no coverage, the current actual position information is not reported, and if the last reported message is the message in the area with weak coverage or no coverage or is not reported, the terminal reports the message that the position information of the user is not in the area with weak coverage or no coverage to the configuration server.

The invention has the beneficial effects that: by changing the existing flow triggered by the circuit domain SCP anchoring, a user can anchor the service from the circuit domain to the IMS domain in a specific access area, a balance point is found in the call completing rate and the connection delay, the call completing rate in a weak coverage area is improved, meanwhile, after the anchoring service is prevented from being started, the service anchoring treatment is carried out in all the access areas, the connection delay of other areas with good coverage is ensured not to be increased, and the service experience of the user is improved.

Drawings

Fig. 1 is a schematic diagram of a calling side scenario anchored to an IMS domain;

FIG. 2 is a schematic flow chart illustrating an embodiment of the present invention;

fig. 3 is an exemplary diagram of a user coverage situation.

Detailed Description

The present invention will be further described with reference to the accompanying drawings, and it should be noted that the present embodiment is based on the technical solution, and the detailed implementation and the specific operation process are provided, but the protection scope of the present invention is not limited to the present embodiment.

As shown in fig. 2, a method for anchoring a service based on a specific area includes the following steps:

s1, the operator pre-defines a weak coverage or no coverage area information list; the area information list is dynamically updated.

The list information may be some areas defined by the GPS information or some areas defined by the cell location information, which may be slightly larger than the actual weak coverage area. As shown in fig. 3.

S2 obtains the area information list when the terminal installed with the VoWiFi APP software logs in for the first time, periodically compares the current actual location information of the user with the area information list after the registration of the IMS network is successfully performed through the VoWiFi network, determines whether the user is currently located in a weak coverage or no coverage area, and synchronously updates the information in the configuration server and the HLR/HSS database as to whether the user is currently located in a weak coverage or no coverage area:

s2.2, after the terminal obtains the relevant information sent by the configuration server, the IMS network is registered through the VoWiFi network; the configuration server inquires the current location information of the user and compares the current location information with the area information list, judges whether the user is in the area with weak coverage or no coverage currently and sends a corresponding result (for example, the current location state used for the user is defined as area _ states, if the current location of the user is in the area with weak coverage or no coverage, the area _ states is sent to be 1, otherwise, the area _ states is sent to be 0) together with the user information to be sent to the HLR/HSS database; after receiving the message sent by the configuration server, the HLR/HSS database sets the relevant information of the database;

specifically, the configuration server will write the information of the subscriber and whether its location is in a weak coverage or no coverage area into the HSS/HLR database through a relevant interface, such as the Sh interface, as shown in table 2. The user initially defaults to not being in a weak or no coverage area, i.e., identified as N. Y indicates that the user position is within the area information list.

TABLE 2

S2.3 the terminal regularly (set as required, and can be 1-2 days or longer) acquires the actual position information of the user after finishing registration, compares the actual position information with the area list information, judges whether the user is in the weak coverage area or the non-coverage area at present, and carries out keep-alive treatment to the configuration server:

the terminal judges that the current actual position information of the user is in a weak coverage area or an uncovered area, and the last reported information is the information in the area list information (namely area _ states is 1), the information is not reported at the present time, and if the last reported information is judged to be the information not in the weak coverage area or the uncovered area (namely area _ states is 0) or the reported information is not reported, the information of the position information of the user in the weak coverage area or the uncovered area is reported to a configuration server;

the terminal judges that the current actual position information of the user is not in the area with weak coverage or no coverage, and the last reported message is a message not in the area information list (namely area _ status is 0), the current actual position information is not reported, and if the last reported message is a message in the area with weak coverage or no coverage (namely area _ status is 1) or is not reported, the terminal reports the message that the position information of the user is not in the area with weak coverage or no coverage to the configuration server.

And if the terminal finds that the area information list of the operator is updated, actively downloading the new area information list.

S2.4, when the configuration server finds that the comparison result between the current actual position information of the user and the area list information changes (namely the value of area _ status changes) after receiving the message, the configuration server initiates a request for updating the data of the HLR/HSS database and sends a message about the comparison result between the current actual position information of the latest user and the area list information to the HLR/HSS database; and after receiving the message, the HLR/HSS database updates the related information.

The subscriber data state storage in the HLR/HSS database is shown in table 3:

TABLE 3

S3, when calling service occurs, the calling user sends voice service to the called user, and sends IAM message to the calling MSC served by the calling user, after the calling MSC receives the calling request, the calling MSC will obtain GT routing information according to the number of the called user, and inquire the routing information to the HLR/HSS database where the called user is located, namely send SRI message;

s4 after receiving the routing information, the HLR/HSS database of the called subscriber performs logical judgment, where the judgment conditions include four categories, that is, whether to sign an anchor SCP (i.e., start a VoWiFi service), whether to be in a weak coverage/no coverage area, whether to register in an IMS-HSS, and whether to register in an HLR, and there are 16 scenarios in total, as shown in table 4:

TABLE 4

The judgment process is as follows:

1) if the called user is found not to sign the anchor SCP service (namely scene 1-8), executing normal routing operation for acquiring the called roaming number, and if the called user signs other intelligent network services, executing corresponding intelligent network flow;

2) if the called user is found to have signed up an anchor SCP service and the position of the called user is not in the weak coverage area or the no coverage area (i.e. scenes 9-12), the user is not anchored to the IMS, and the following operations are performed in each case:

2.1) if the user is not on the network (i.e. scene 9, no registration information exists in IMS-HSS and HLR), returning prompt information (such as returning shutdown or other information);

2.2) if the user logs in the circuit domain (namely, scenes 10 and 12, registration information exists in the HLR), executing a normal signaling flow for acquiring the route;

2.3) if the user is on the network but not in the circuit domain login (i.e. scenario 11, there is registration information in IMS-HSS but no registration information in HLR), it indicates that it is possible to log in via VoWiFi, and the operator can do the process according to the policy: when the VoWiFi service is not allowed to be used under the condition of good signals, which means that the connection in a VoWiFi mode is not allowed when the called party is called, the HLR/HSS database is required to make the called party not anchored to the IMS domain, and a normal signaling flow for acquiring the route is executed;

if the user is allowed to use the VoWiFi service under the condition of good signal coverage, the charging mode of the existing circuit domain call may be impacted.

3) If the called user is signed up for the anchoring SCP service and the current position is also in a weak coverage area or a no coverage area (namely scenes 13-16), the called user is anchored to the IMS, and the VoWiFi APP answers the call, and the following operations are carried out according to the situation:

3.1) the called user is not on the network (i.e. scenario 13, there is no registration information in both IMS-HSS and HLR), then a prompt message is returned (e.g. a shutdown message or other messages are returned);

3.2) the called user VoWiFi APP is not registered (i.e. scene 14, there is no registration information in IMS-HSS, there is registration information in HLR), although the signal is not good, the mobile phone is not turned off, the circuit domain call is still allowed, even if the quality may be poor, or a prompt message is sent to the called user to prompt the called user to log in APP to call back the calling user (for example, a short message is sent to prompt 'A user to dial you, please use APP to log in, call back the user');

3.3) if the called user is judged to be registered with the IMS-HSS, anchoring to the IMS domain, and connecting the call through the VoWiFi APP.

Specifically, the method comprises the following steps:

if the user execution strategy is judged to be failure to influence (namely the user is not registered in any domain), feeding back a corresponding message to the calling MSC/VLR. (i.e., scene 9, scene 13)

If the user execution strategy is judged to be not anchored, namely the user execution strategy is routed to the circuit domain, the step 3' (namely scenes 1-8 and scenes 10 and 12 are executed, and if the VoWiFi service is not allowed to be used under the condition of good signals, a scene 11 is also included; a scene 14 is also included);

if the user execution policy is judged to be anchored, namely, the user execution policy is routed to the IMS domain, then step 3 (scene 15 and scene 16) is executed;

step 3': the HLR/HSS where the called user locates initiates a message of fetching the Roaming Number (MSRN) to the VLR where the called user locates, namely, sends PRN (provider _ Roaming _ Number), and the called MSC fetches the Roaming Number of the called user. The called MSC returns the roaming number to the calling MSC through the HLR;

step 4': the calling MSC sends an IAM message to the called MSC according to the roaming number;

step 5': the called MSC sends a paging message to the called user B, thereby completing the normal call.

Step 3, the called HLR/HSS sends the IMS domain roaming number (here, the mode of (calling number A, prefix + called number B) can also be adopted, the message is sent to the gateway of the circuit domain from the calling MSC/VLR, and is sent to the IMS network through the analysis of the gateway) to the calling MSC/VLR;

step 4, the calling MSC sends IAM information to GMSC/MGCF route to IMS domain;

and step 5, the IMS domain addresses the address information of the called user B and sends the address information to the called user B through the invite message, thereby completing normal calling.

Various changes and modifications can be made by those skilled in the art based on the above technical solutions and concepts, and all such changes and modifications should be included in the scope of the present invention.

Claims

1. A service anchoring method based on a specific area is characterized by comprising the following steps:

s3, when calling service occurs, calling user sends voice service to called user, sends IAM message, i.e. initial address message to calling MSC served by calling user, after calling MSC receives calling request, according to called user number, it will obtain global title GT routing information, and sends message requesting routing information, i.e. SRI message, to HLR/HSS database where called user is located;

1) if the service control point service (SCP service) of the anchoring intelligent network which is not signed by the called user is judged to be found, executing normal routing operation for acquiring the called roaming number, and if the called user signs other intelligent network services, executing the corresponding intelligent network flow;

3.1) the called user has no registration information in IMS-HSS and HLR, then the prompt information is returned;

2. The method for anchoring service based on specific areas according to claim 1, wherein in step S1, the operator dynamically updates the area information list.

3. The method for anchoring services based on specific areas according to claim 1, wherein the step S2 is as follows:

s2.1, when a terminal logs in for the first time, a request is sent to a configuration server, the request message carries the current position information of a user, and after the configuration server receives the request, the relevant information of the user is sent to the terminal, wherein the relevant information comprises the configuration information of an IMS access point conversation border controller (SBC) and the area information list;

4. The method for anchoring service based on specific areas as claimed in claim 3, wherein in step S4, the specific method of keep-alive processing is: