RU2487503C1 - Method of implementing local exchange, mobile switching centre and communication system - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: when both callers are located in a first MSC and a second MSC respectively, the first MSC, in whose zone the first caller is located, obtains the local exchange information of the second caller transferred by the second MSC, then processes the local exchange according to the local exchange information of the first caller and the local exchange information of the second caller, wherein the local exchange information of the first caller or the local exchange information of the second caller includes information about the base station controller (BSC) in whose zone the first caller or the second caller is located. According to the method, in MSC POOL network conditions, even if the caller or called subscriber is located in the zone of different MSC, respectively, the caller or the called subscriber can also know the BSC in whose zone the peer call subscriber is locate and judge whether to start the local exchange in order to process the local exchange in.

EFFECT: providing local exchange.

22 cl, 11 dwg

Description

FIELD OF THE INVENTION

The present invention relates to the field of communication technology, and in particular to a method for switching to local reception, a mobile switching center (MSC) and a communication system.

BACKGROUND

A data network is an important component of a wireless communication network. Reducing the load on the resources of the data transmission network (hereinafter referred to as transmission resources here) can help reduce the costs of creating and operating the network. Switching to local reception is an effective solution to reduce the load on transmission resources.

Switching to local reception is a technical solution in which, during a communication session in which the calling subscriber and the called subscriber are in the same base station subsystem (BSS), the voice link circuit within the BSS subsystem is closed, i.e., voice user plane data does not flow from the BSS subsystem, so as to save transmission resources of a specific interface. Switching to local reception can be divided into switching to local reception at a base transceiver station (BTS) and switching to local reception at a base station controller (BSC). Switching to local reception at the BTS station means that both subscribers of the communication session are located in the zone (action) of one BTS station or one BTS cluster (in the case of cascading connection of BTS stations), and the voice link circuit occurs at the corresponding BTS station. Switching to local reception on the BSC controller means that both subscribers of the communication session are in the zone (action) of one BSC controller, but different BTS stations (or BTS clusters), and the voice link circuit appears on the corresponding BSC controller. By setting the switch to local reception on the BTS station, you can save transmission resources in the Abis interface (the interface between the BTS station and the BSC controller), the Ater interface (the interface between the BTS station and the BSC controller) and the A interface (the interface between the BSS subsystem and the MSC center), and by setting the switch to local reception on the BSC controller, you can save transmission resources in the A interface.

The prior art defines a method for switching to local reception in a non-MSC pool network environment. According to this method, mainly the MSC center determines whether to start switching to local reception, evaluating whether the calling subscriber and the called subscriber located in the area of one MSC center belong to one BSC controller, and if the conditions for starting switching to local reception are satisfied. If the calling subscriber and the called subscriber belong to the same BSC controller, and the conditions for the start of switching to local reception are satisfied, then the MSC center gives the instruction to start switching to local reception in the BSC controller, and the BSC controller performs the operation of setting the switch to local reception. After receiving the message to complete the setup of switching to local reception from the BSC controller, the MSC center releases the resources of the interface circuit A used by the calling subscriber and the called subscriber. The conditions for the start of switching to local reception mean that there are no additional services or operations that are not performed, such as notification or authorized interception of signals. After the start of switching to local reception, if an additional service occurs or operations are performed, such as alerting or allowed signal interception, or the BSC controller of the calling subscriber is different from that of the called subscriber due to the transfer of control, the switching to local reception must be disconnected. In this case, the MSC center may require that the BSC controller disconnect the switch to local reception by sending an alert.

In the process of research and implementation of the prior art, the inventor of the present invention found that in the prior art there is no necessary solution for switching to local reception, available in the conditions of the MSC POOL network.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method for switching to a local reception, an MSC of a center and a communication system, such that switching to a local reception can be carried out in an MSC POOL network.

A method for switching to local reception includes:

when both call subscribers are in the zone of the first MSC center and the second MSC center, respectively, receiving by the first MSC center, in the zone of which the first call subscriber is, information on switching to local reception of the second call subscriber sent by the second MSC center; and

execution by the first MSC of the local reception switching processing center according to local switch information of the first call subscriber and local switch information of the second call subscriber, wherein local switch information of the first call subscriber or local switch information of the second call subscriber respectively information of the BSC of the controller in the area of which the corresponding first call subscriber or second call subscriber is located.

Mobile Switching Center (MSC) includes:

a receiving unit configured to receive local switch information of the second call subscriber sent by the second MSC center when both call subscribers are in the area of the first MSC center and the second MSC center, respectively; and

a processing unit configured to perform local switch switching processing according to local switch information of the first call subscriber and local switch information of the second call subscriber, wherein local switch information of the first call subscriber or local switch information of the second call subscriber respectively information of the BSC controller, in the area of which there is the corresponding first call subscriber or second call subscriber.

The communication system includes a first MSC center and a second MSC center.

The first MSC center is configured so that when both call subscribers are in the area of the first MSC center and the second MSC center, respectively, receive switching information for local reception of the second call subscriber sent by the second MSC center and perform local switching switching processing according to the switching information to the local reception of the first call subscriber and the switching information to the local reception of the second call subscriber, wherein the switching information to the local reception of the first call subscriber or the switching information to and local reception of the second call subscriber accordingly includes BSC information of the controller in the area of which there is the corresponding first call subscriber or second call subscriber.

The second MSC center is configured to send local switch information of the second call subscriber to the first MSC center.

In embodiments of the present invention, switchover information for local peer-to-peer call reception sent by the MSC peer center of the call subscriber is received, and switchover processing for local receive is performed according to switchover information for local peer-to-peer call and switchover information for local peer-to-peer call. Thus, under MSC POOL network conditions, even if the calling subscriber and the called subscriber are in the zone of different MSC centers, the calling subscriber or the called subscriber can also recognize the BSC controller in the zone of which the calling subscriber or the called subscriber is located. Therefore, in order to perform the switchover processing to local reception, a decision can be made whether to begin switching to local reception.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further explained in the description of specific options for its implementation with reference to the accompanying drawings, in which:

FIG. 1 is a flowchart of a method according to Embodiment 1 of the present invention; FIG.

2A and 2B are a flowchart of a method according to Embodiment 2 of the present invention;

FIG. 3 is another flowchart of a method according to Embodiment 2 of the present invention; FIG.

4 is another flowchart of a method according to Embodiment 2 of the present invention;

5A and 5B are a flowchart of a method according to Embodiment 3 of the present invention;

6 is another flowchart of a method according to Embodiment 3 of the present invention;

7 is another flowchart of a method according to Embodiment 3 of the present invention;

FIG. 8 is a block diagram of an MSC center according to an embodiment of the present invention; FIG. and

FIG. 9 is a block diagram of a communication system according to an embodiment of the present invention; FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Technical solutions in embodiments of the present invention are explained below with reference to the accompanying drawings. Obviously, the embodiments described below are not all embodiments of the present invention, but only part of them. Those skilled in the art may derive other embodiments from the embodiments of the present invention without making creative efforts, and all such embodiments are within the scope of the present invention.

Under MSC POOL network conditions, due to the fact that the calling subscriber and the called subscriber can be in the zone of one BSC controller, but different MSC centers, the MSC center in the zone of which the calling subscriber is located, or the MSC center in the zone of which the called subscriber is not can find out the BSC controller in the area of which the called party is located, or the BSC controller in the area of which the called party is located. Therefore, MSC centers cannot evaluate whether to begin switching to local reception. In addition, if the switch to local reception cannot be started due to the fact that the call is intercepted at one of the MSC centers or operations such as a notification and additional service are performed, the other MSC center cannot know such details. In order to switch to local reception in an MSC POOL network, embodiments of the present invention provide a method for switching to local reception, an MSC center, and a communication system. Details are illustrated below.

OPTION 1

The present embodiment takes into consideration some MSC center for description. It should be noted that in this embodiment, a local subscriber and an equal subscriber are provided for the call. For example, from the perspective of the caller, the caller is a local subscriber, and the callee is a peer; from the perspective of the called subscriber, the called subscriber is a local subscriber, and the calling subscriber is a peer. In such an embodiment of the present invention, the local subscriber MSC center is called the first MSC center, while the peer MSC center is called the second MSC center. Therefore, the first MSC center and the second MSC center can be the MSC center of the caller or the MSC center of the called subscriber. When the first MSC center is the MSC center of the calling party, the second MSC center is the MSC center of the called party, and when the first MSC center is the MSC center of the called party, the second MSC center is the MSC center of the calling party. The solution is disclosed as follows:

The method for switching to local reception includes: when both call subscribers are in the area of the first MSC center and the second MSC center, respectively, the first MSC center receives switching information for local reception of the second MSC center, and performs local switching switching processing according to the switching information to receive the first MSC center locally and switch information to the local reception of the second MSC center. Due to the fact that the MSC center of the caller can exchange local switch information with the MSC center of the called subscriber, both MSC centers can fully know each other local switch information. Therefore, the local switch switching processing can be performed according to the complete local switch information (including the local switch information of both the calling subscriber and the called subscriber). As shown in FIG. 1, a specific process may include the following steps:

Step 101: The first MSC center receives the switching information to the local peer reception sent by the second MSC center.

For example, the first MSC center may receive local switch switching information sent by the second MSC center via mobile application subsystem (MAP) signaling or trunk signaling, the local switch switching information may include BSC signaling node information and the capability information switching to local reception of an equal call subscriber. Of course, the local switch information further includes other information required to set or disconnect the local switch, for example, call identifier information or channel information A of the interface. The information of the signaling node of the BSC controller is the information of the BSC controller in which the call branch of a specific subscriber is located (the call branch is a call to a specific subscriber, for example, the call includes a calling subscriber and a called subscriber; each call subscriber is called a call branch), and may be information of the signaling node of the BSC controller in which the subscriber of the office call of the first MSC center or the second MSC center is located. An assessment of whether the BSC controllers of the calling subscriber and the called subscriber are the same BSC controller can be made according to the information of the signaling node of the BSC controller. Then, according to the result of this assessment, an assessment can be made as to whether to switch to local reception. Information about the possibility of switching to local reception shows whether there is a call pickup or whether operations such as a notification or an additional service are being performed. Whether the peer can switch to local reception can be estimated according to the information of the possibility of switching to the local peer reception. The call identifier (ID) is used to identify the calling information of the calling subscriber and the called subscriber. After the MSC switching the local reception receives the call ID of the peer of the call, it provides the BSC controller with the call identifiers of both the calling subscriber and the called subscriber, so that the BSC controller switches to the local reception according to the call identifiers. The information of the transmission channel A of the interface is used at the time when the MSC switching the local reception disconnects the switching to the local reception.

If the calling subscriber and the called subscriber provide local switching information via the MAP subsystem signaling (that is, transmit local switching information via the MAP signaling channel), then the calling subscriber or the called subscriber can receive the MSC address of the calling subscriber or the called subscriber MAP signaling according to the received MSC peer address, and perform call association using international identification number information Caller ID (IMSI). In this way, the MSC center can perform the local switch switching processing of the associated call according to the local switch switching information of both the calling subscriber and the called subscriber in subsequent processes. That is, before the first MSC center receives the switch information for local peer reception sent by the MSC peer through the MAP signaling, the first MSC center can also send the MSC center address and IMSI information of the local subscriber identifier to the peer MSC center. Then, the peer MSC center can send the local peer switching information to the local subscriber MSC according to the local subscriber center MSC address, where the peer local switching information carries the IMSI information of the local subscriber identifier. Thus, after receiving the switching information to the local peer-to-peer reception, the local subscriber MSC center can associate the call according to the IMSI information of the local subscriber identifier carried in the received switching information to the local peer-to-peer, and then perform the switching processing to the local receiving of the associated call according to the information switching to the local reception of both the local subscriber and the equal subscriber.

Step 102: The first MSC center performs local switch switching processing according to the local switch local switch information and the local switch switch information of the second MSC center as an equal subscriber, for example, the first MSC center sets the local switch or disconnects the local switch.

For example, if the first MSC center determines, according to the information of the BSC signaling nodes of the controller of both the local subscriber and the equal subscriber, that both the local subscriber and the equal subscriber belong to one BSC controller, then the first MSC center notifies the BSC controller of the start of switching to local reception and notifies a mobile gateway station (MGW) about releasing resources A of a local subscriber interface. In addition, if the local switchover information further includes local switchover information, then the first MSC center can continue to evaluate, that is, the first MSC center determines, according to the local switchover information of both the local subscriber and the peer, whether both the local subscriber and the equal subscriber have the ability to start switching to local reception. When the evaluation result is positive, the first MSC center notifies the BSC controller of the start of switching to local reception, and notifies the MGW gateway about the release of resources A of the local subscriber interface. If the switching information to the local reception does not include the possibility of switching to the local reception, then to ensure the correct switching to the local reception, the second MSC center can evaluate whether the second MSC center has the ability to switch to the local reception before providing the first MSC Information switching center for local reception. The second MSC center provides the first MSC center with switching information for local reception, if the second MSC center has the ability to switch to local reception. However, the first MSC center can evaluate whether the second MSC center has the ability to switch to local reception before receiving information to switch to local reception of the second MSC center, or before processing the switch to local reception. The first MSC center performs the corresponding operations if the first MSC center has the ability to switch to local reception. Of course, the first MSC center can also evaluate whether to begin switching to local reception immediately or according to the information of the signaling nodes of both the calling subscriber and the called subscriber, without considering the information of the possibility of switching to local reception.

After notifying the MGW of the gateway about the release of resources of the local subscriber interface A, the first MSC center can also send a local switching response ADD_REPLY to the peer MSC center, so that the MSC peer can notify the MGW gateway about the release of resources of the peer interface A according to the response ADD_REPLY switching to local reception. That is, both - the calling subscriber and the called subscriber - can make a conclusion about switching to local reception, and start switching to local reception, respectively, or only one of them, the calling subscriber or called subscriber, makes an assessment about switching to local reception, and first starts switching to local reception, and then notifies the other party.

After setting the switch to local reception, if the switch to local reception needs to be disconnected, for example, if permitted interception is necessary, or when operations such as notification and additional service are performed, the first MSC center may request access to resources A of the local subscriber interface from the MGW gateway according to the local switch information of both the local subscriber and the peer. If the request for access to resources of the local subscriber interface A is successful, then the first MSC center can send the request to disconnect the local switch to the second MSC center, so that the second MSC center accesses the resources A of the local subscriber interface from the MGW gateway according to the request to disconnect the local switch reception; after receiving a confirmation (ACK), which returns from the second MSC center and indicates that access to the resources of the local subscriber interface A has been obtained successfully, the first MSC center notifies the BSC controller of the disconnection of switching to local reception. It should be noted that after the second MSC center has successfully accessed the resources of the interface A, the second MSC center also notifies the BSC controller of the disconnection of the switch to local reception, and then returns to the ACK confirmation step indicating that the first MSC center has successfully accessed peer A resources.

Alternatively, after setting the switch to local reception, if the switch to local reception needs to be disconnected, then the first MSC center may not first ask for access to resources A of the local subscriber’s interface, but will directly send the request for disconnecting the switch to local reception to the second MSC center, so the second The MSC center requests access to resources of the peer interface A from the MGW gateway according to the request for disconnecting the switch to local reception. After receiving a confirmation (ACK), which returns from the second MSC center and indicates that access to resources of the peer interface A has been obtained successfully, the first MSC center requests access to resources A of the local subscriber interface; in case of refusal to access resources A of the local subscriber interface, the first MSC center does not disconnect the switch to local reception; may not at first request access to resources A of the local subscriber interface, but if access to resources A of the local subscriber interface is successful, the first MSC center notifies the BSC controller of the disconnection of switching to local reception.

From the preceding description, it can be understood that in this embodiment, switching information for a local peer reception is received; the local switch switching processing is performed according to the local switch switching information of both the local subscriber and the peer. Thus, in the conditions of the MSC POOL network, even if the calling subscriber or the called subscriber are in the zone of different MSC centers, the MSC center in the zone of which the called subscriber is located can recognize the BSC controller, in the area of which the called party is located, or the BSC controller, in the area of which the called party is located. Therefore, an assessment can be made as to whether to switch to local reception. Additionally, information of switching to the local peer reception received by the MSC peer center is received. Therefore, if the switch to local reception cannot be started due to the fact that the call is intercepted at one of the MSC centers or operations such as a notification and additional service are performed, the other MSC center may know such details that facilitate the switch to local reception.

It should be noted that in the previous embodiment, one subscriber switches to local reception after receiving information from another subscriber to make an assessment. However, in the actual implementation, both the calling subscriber and the called subscriber can obtain each other's information to make an estimate, and then can perform the local switch switching processing. The following example can be taken as a solution.

The first MSC center receives the local switch information of the second MSC center and performs local switch processing according to the local switch information of both the first MSC and the second MSC.

The second MSC center receives local switch information of the first MSC center and performs local switch processing according to the local switch information of both the first MSC and the second MSC.

OPTION 2

According to the method provided in Embodiment 1 of the present invention, the present embodiment describes how to switch to local reception by exchanging local switch information between MSC centers via MAP signaling. The solution includes the following steps:

Stage 1: the MSC center of the calling subscriber and the MSC center of the called subscriber transmit information switching to local reception in the MAP signaling and transfer the MAP signaling to each other.

One MSC center sends switching information to local reception of a local subscriber to another MSC center using MAP signaling. After receiving the switching information to the local peer reception, another MSC center stores the received switching information to the local reception of the MSC center, and returns the switching information to the local reception of the local subscriber to the MSC center using the MAP signaling. If the switching information for local reception of one MSC center changes during the call, the MSC center needs to send the changed information for switching to local reception in another MSC center, so as to ensure that the MSC centers of both the calling subscriber and the called subscriber fully know each other’s information simultaneously , and the local switch switching processing according to the full local switch information, that is, the local switch information of both MSC centers, is performed.

Step 2: The MSC center of the calling subscriber and the MSC center of the called subscriber perform mutual addressing in the MAP signaling according to the MSC address of the peer. This method of obtaining a peer MSC address by the MSC center of the caller by the MSC center and the MSC center of the called party (i.e., the MSC center of the called party receives the MSC address of the called party, and the MSC center of the called party receives the MSC address of the called party):

During call setup, the MSC of the calling subscriber and the MSC of the called subscriber transmit the IMSI information of the identifier of the calling subscriber and the called subscriber and the MSC addresses of both the calling subscriber and the called subscriber via the SEND ROUTING INFORMATION (SRI) request, the SECURE ROAMING NUMBER (PRN) request, the response ENSURE ROAMING NUMBER (PRN ack) and response SEND ROUTING INFORMATION (SRI ack).

For example, the caller initiates a call; The MSC of the caller sends SRI information to the home location register (HLR, RMD) to obtain the routing information of the called subscriber, wherein the SRI information carries the MSC address of the caller and the IMSI identifier of the caller; The HLR register sends a PRN request to the MSC of the called subscriber to obtain the roaming number of the called subscriber, and the PRN request carries the MSC address of the caller and IMSI information of the caller ID; The MSC of the called party stores the MSC address of the calling party and the IMSI information of the calling party ID. When the MSC of the caller returns a PRN ack response to the HLR register, the PRN ack response carries the MSC address of the called party and IMSI information of the called party ID. When the HLR register returns the SRI ack response to the MSC center of the caller, the SRI ack response carries the MSC address of the called subscriber and the IMSI information of the called subscriber, and the MSC center of the caller stores the MSC address of the called subscriber and the IMSI information of the called subscriber.

Stage 3: the MSC center of the caller and the MSC center of the called party associate the call using IMSI information. That is, after the MSC center of the calling subscriber and the MSC center of the called subscriber receives the local switch information MSC of the peer center, they associate the corresponding call using the IMSI call information within the MSC of the local subscriber center. Therefore, the MSC of the calling subscriber center and the MSC of the called subscriber need to obtain IMSI information of the peer by transmitting IMSI information of the peer call branch in the MAP signaling sent to the peer. Refer to the previous description of step 2.

The preceding MAP signaling used to transfer the switching information to local reception can be obtained by converting the current MAP signaling at runtime, for example, by expanding the SRI and PRN of the current MAP signaling or by adding MAP signaling. In this embodiment, the fact that MAP signaling is added is taken as an illustrative example. It is assumed that the added MAP signaling is called as [MAP LCLS service] and the signaling can carry the following information (select and carry the following information according to various scenarios):

(1) IMSI peer identifier.

(2) Information of the signaling node of the BSC controller in which the intra-office call is located.

(3) Indication of switching to local reception, used to transmit information about the possibility of switching to local reception. For example, the following types of indications can be used:

Local Local Call Reception (LCLS) switching ADD_REQ, LCLS switching is enabled, LCLS switching is rejected, LCLS switching is disabled, LCLS switching is rejected, LCLS switching is denied, LCLS switching is enabled, LCLS switching is set, and LCLS switching is disabled .

(4) The Call-ID call identification number corresponding to the in-office call, in which the Call-ID is used to identify the call branch between the MSC center and the BSC controller.

(5) Information channel transmission A interface inside the office; The information of the transmission channel A of the interface of the two call branches should be used when the BSC controller disconnects the switch to local reception.

The solution is described in detail below with reference to several specific scenarios. For simplicity, the following description is based on the assumption that the calling terminal is designated MS-A, the MSC of the calling party is indicated by MSC-A, the called terminal is indicated by MS-B, and the MSC of the called party is indicated by MSC-B.

1. Scenario 1: Call setup process

During the call setup, the MSC centers of both the calling subscriber and the called subscriber, i.e., MSC-A and MSC-B, transmit the IMSI information of both the calling subscriber and the called subscriber and the address information of the MSC centers of both the calling subscriber and the called subscriber via SRI information, PRN request , PRN ack and SRI ack. As shown in FIGS. 2A and 2B, a specific process may include the following steps:

A201: The MS-A terminal sends a CM service request to the MSC-A center.

A202: The MSC-A center performs authentication and encryption with respect to the MS-A terminal, for example, the MSC-A center exchanges an authentication and encryption message with the MS-A terminal.

A203: The MS-A terminal sends a setup message to the MSC-A center, and the MSC-A center returns a call continue message to the MS-A terminal.

A204: The MSC-A center sends an ADD_REQ request to the MGW gateway, and the MGW gateway returns an ADD_REPLY response to the MSC-A center.

A205: MSC-A center sends ASS_REQ request to BSC controller; The BSC controller sends the ASS_CMD command to the MS-A terminal; The MS-A terminal returns an ASS_COMP message to the BSC controller; The BSC controller returns the ASS_RSP response to the MSC-A center.

A206: The MSC-A center sends to the HLR register SRI the routing information of the MS-B terminal, where the SRI information carries the address of the MSC-A center and the IMSI identifier of the MS-A terminal.

A207: The HLR register sends a PRN request to the MSC-B center to receive the roaming number of the caller, the PRN request carrying the address of the MSC-A center and IMSI information of the MS-A terminal.

A208: The MSC-B center stores the address of the MSC-A center and the IMSI information of the MS-A terminal. When the MSC-B center returns a PRN ack confirmation to the HLR register, the PRN ack acknowledgment carries the address of the MSC-B center and the IMSI information of the MS-B terminal.

A209: The HLR register returns an SRI ack confirmation to the MSC-A center, the SRI ack confirmation carries the address of the MSC-B center and IMSI information of the MS-B terminal, and the MSC-A center stores the address of the MSC-B center and IMSI information of the MS-B terminal .

A210: The MSC-A center again sends an ADD_REQ request to the MGW gateway, and the MGW gateway returns an ADD_REPLY response to the MSC-A center.

A211: Through exchange and addressing in steps A206 through A208, the MSC-A center and the MSC-B center associate a call according to the IMSI information of the respective peers stored in the MSC-A center and the MSC-B center. The MSC-A center sends a start address (IAM) message to the MSC-B center; The MSC-B center sends a page to the BSC controller; The BSC controller sends a page to the MS-B terminal; The MS-B terminal can return a page response (Page rsp) to the BSC controller; after receiving the Page rsp response, the controller can send the Page rsp response to the MSC-B center.

A212: The MSC-B center performs authentication and encryption with respect to the MS-B terminal, for example, the MSC-B center exchanges an authentication and encryption message with the MS-B terminal. Meanwhile, the MSC-B center sends an ADD_REQ request to the MGW gateway, and the MGW gateway returns an ADD_REPLY response to the MSC-B center; The MSC-B center sends a setup message to the MS-B terminal, and the MS-B terminal returns a Call Confirmed message to the MSC-B center.

A213: The MSC-B center again sends an ADD_REQ request to the MGW gateway, and the MGW gateway returns an ADD_REPLY response to the MSC-B center.

A214: The MSC-B center sends an ASS_REQ request to the BSC; The BSC controller sends the ASS_CMD command to the MS-B terminal; The MS-B terminal returns an ASS_COMP message to the BSC controller; The BSC controller returns the ASS_RSP response to the MSC-B center.

A215: The MS-B terminal can send an ALERT (alarm) message to the MSC-B center; The MSC-B center sends the final address message (ACM) to the MSC-A center; The MSC-A center sends an ALTERT alarm message to the MS-A terminal. Then, the MS-B terminal sends a CONNECT (connection) message to the MSC-B center, and the MSC-B center can return a CONNECT_ACK (connection confirmation) message to the MS-B terminal; The MSC-B center sends an Answer Message (ANM) to the MSC-A center; The MSC-A center sends a CONNECT connection message to the MS-A terminal, and the MS-A terminal can return a CONNECT_ACK (connection confirmation) message to the MSC-A center. By this time, the call setup process between the MS-A terminal and the MS-B terminal is completed.

A216: The MSC-B center sends to the MSC-A center a request for LCLS switching information (LCLS info Req) according to the address of the MSC-A center. The MAP signaling used to transfer the switching information to the local reception carries information of the signaling node of the BSC controller where the MS-B terminal is located, information about the possibility of switching to the local reception of the MSC-B center and the Call-ID (call identifier) of the MS-B terminal.

A217: The MSC-A center evaluates whether the conditions for initiating a switch to local reception are met; if the conditions for the start of switching to local reception are satisfied, then the MSC-A center starts switching to local reception, that is, step A218 is performed.

For example, the MSC-A center determines, according to the information of the signaling node of the BSC controller in which the MS-A terminal is located, and the information of the signaling node of the BSC controller in which the MS-B terminal is located, both call subscribers belong to the same BSC controller.

If both subscribers of the call belong to one BSC controller, then the MSC-A center determines, according to the information of the possibility of switching to local reception of the MSC-A center and the information of the possibility of switching to local reception of the MSC-B center, that both subscribers of the call have the ability to start switching to local reception (for example, the encoding and decoding of the calling subscriber and the called subscriber are the same; the BSC controller of the called subscriber supports switching to local reception, and the caller is not eavesdropped), the MSC-A center notifies The BSC controller, in the area of which the MS-A terminal is located, starts switching to local reception (step A218), and notifies the MGW of the gateway about the release of resources A of the terminal MS-A interface (step A219). If the MSC-A center determines that the local office is not able to start switching to local reception, then the MSC-A center returns an LCLS info Cnf message (approval of the local switch to local call reception information), which carries an indication that the local switch Reception is not permitted for the MSC-B Center. After the MSC-B center receives the LCLS info Cnf approval, if the LCLS info Cnf approval indicates that switching to local reception is not allowed, then the MSC-B center may not start switching to local reception.

If the MSC-A center does not have restrictions to start switching to local reception, but the MS-A terminal and the MS-B terminal do not belong to the same BSC controller, then the MSC-A center returns directly to the MSC-B center the message LCLS info Cnf, and LCLS info Cnf message carries information of the BSC signaling node of the terminal MS-A controller and the corresponding Call-ID identifier.

In the present embodiment, assuming that the MS-A center and the MS-B center belong to one BSC controller and that both the MS-A center and the MS-B center have the ability to start switching to local reception, the MSC-A center starts switching to local receiving after receiving the LCLS info Req request sent by the MSC-B center, that is, step A218 is performed.

A218: The MSC-A center sends a local switching LOCAL SWITCH COMMAND command to the BSC controller to start the local switching, the BSC controller returns a local switching local LOCAL SWITCH COMP message to the MSC-A center; The MSC-A center returns an LCLS info Cnf message to the MSC-B center, and the LCLS info Cnf message carries information of the BSC signaling node of the MS-A center controller and the corresponding Call-ID identifier, and indicates that the switch to local reception has already begun.

It should be noted that if the BSC controller could not start switching to local reception, the MSC-A center carries the information of the BSC signaling node of the MS-A terminal controller in the LCLS info Cnf message, returning the LCLS info Cnf message to the MSC-B center, and shows that the switch to local reception did not start.

A219: The MSC-A center sends a SUB_REQ request to the MGW gateway to free up the A resources of the terminal MS-A interface. The MGW gateway may return a SUB_REPLY response to the MSC-A center.

A220: After the MSC-B center receives the LCLS info Cnf message returned from the MSC-A center, if the LCLS info Cnf message indicates that the switch to local reception has already begun, the MSC-B center sends a SUB_REQ request to the MGW gateway, to free up the resources of the terminal MS-B interface. The MGW gateway may return a SUB_REPLY response to the MSC-B center. If the LCLS info Cnf message indicates that the switch to local reception has not started, then the MSC-B center does not perform operations.

By this time, the installation of switching to the local reception is completed. It should be noted that the MAP connection should not be supported between the MSC center of the calling party and the MSC center of the called party, that is, between the MSC-A center and the MSC-B center. In addition, after the switch to local reception has begun, trunk resources between the MSC-A center and the MSC-B center are not released. If trunk resources are freed, then switching to local reception, which is already installed, cannot be subsequently disconnected.

Of course, an LCLS info Req request can be initiated by the MSC-A center first. The execution method is similar to the method in which the MSC-B center first initiates an LCLS info Req request. That is, after the MSC-B center receives the LCLS info Req request sent from the MSC-A center, the MSC-B center determines whether both call subscribers belong to the same BSC controller, according to the information of the signaling node of the BSC controller in which the MS- A terminal, and information of the signaling node of the BSC controller in which the MS-B terminal is located; if both subscribers of the call belong to the same BSC controller, then the MSC-B center determines, according to the information of the possibility of switching to local reception of the MSC-A center and information of the possibility of switching to local reception of the MSC-B center, that both subscribers of the call have the ability to start switching to local reception (for example, the encoding and decoding of the calling subscriber and the called subscriber are the same; the BSC controller of the called subscriber supports switching to local reception, and the caller is not eavesdropped). In this case, the MSC-B center notifies the BSC controller, in the area of which the MS-B terminal is located, of the start of switching to local reception, and notifies the MGW of the gateway about the release of resources A of the terminal MS-B interface. In addition, the MSC-B center also returns an LCLS info Cnf message to the MSC-A center, and the LCLS info Cnf message carries information of the BSC signaling node of the center controller MS-B and the corresponding Call-ID identifier, and indicates that the switch to local reception is already started. If the MSC-B center determines that the local office is not able to start switching to local reception, then the MSC-B center [sends a message that] indicates that switching to local reception is not allowed in the LCLS info Cnf message returned to MSC-A center. After the MSC-A center receives the LCLS info Cnf message, if the LCLS info Cnf message indicates that switching to local reception is not allowed, then the MSC-A center may not start switching to local reception. If the MSC-B center has no restrictions in order to start switching to local reception, but the MS-A terminal and the MS-B terminal do not belong to the same BSC controller, then the MSC-B center returns the LCLS info Cnf message directly to the MSC-A center, and LCLS info Cnf message carries information of the BSC signaling node of the terminal MS-B controller and the corresponding Call-ID identifier.

In addition, it should be noted that in addition to the previous case, in which the MSC of the subscriber center makes an assessment and starts switching to local reception, the MSC center of the caller and the MSC center of the called subscriber can also make an assessment and start switching to local reception, respectively. For example, after step A216, the MSC-A center may return an LCLS info Cnf message to the MSC-B center, the MSC-A center and the MSC-B center evaluate whether the appropriate conditions are met to start switching to local reception; if their respective conditions for starting switching to local reception are satisfied, then the MSC-A center and the MSC-B center begin switching to local reception, respectively. That is, on the one hand, the MSC-A center notifies the BSC controller in the area of which the MS-A terminal is located, of the start of switching to local reception, and notifies the MGW of the gateway about the release of resources A of the terminal MS-A interface; on the other hand, the MSC-B center also notifies the BSC controller, in the area of which the MS-B terminal is located, of the start of switching to local reception, and notifies the MGW of the gateway about the release of resources A of the MS-B terminal interface.

During the call, the MSC-A center and the MSC-B center can update the local switch reception information by using the LCLS info Req request and the LCLS info Cnf message. That is, when the information of the possibility of switching to local call reception changes, the MSC-A center must interact dynamically with the MSC-B center. For example, when a call is initiated, the switch to local reception does not start, because the MS-A terminal and the MS-B terminal do not belong to the same BSC controller. However, there are no other restrictions on switching to local reception. In the current call process, if the user of the MS-A terminal is eavesdropping or an additional service occurs, the MSC-A center must notify the MSC-B center that the call does not have the ability to switch to local reception; if the eavesdropping subsequently ends or the additional service ends, the MSC-A center must notify the MSC-B center that the call has the ability to switch to local reception. When a call does not have the ability to switch to local reception, even if both the calling subscriber and the called subscriber belong to the same BSC controller, switching to local reception does not start.

2. Scenario 2: After setting the switch to local reception, the MSC center requests the disconnect switch to local reception.

When the MSC-A center needs to disconnect the switch to local reception due to the occurrence of operations such as an additional service, the MSC-A center asks for access to the interface resources A from the MGW of the gateway according to the local switch information for the two call subscribers; if the MSC-A center successfully gained access to the resources of the interface A, the MSC-A center sends an LCLS info Req request to the MSC-B center, notifies the MSC-B center and asks the MSC-B center to disconnect the local switch; after the MSC-B center receives the LCLS info Req request, the MSC-B center gains access to the A resources of the interface from the MGW of the gateway, according to the request for disconnecting the switch to local reception; if the MSC-B center can access the resources of the interface A, the MSC-B center returns to the MSC-A center the LCLS info Cnf message and transmits the corresponding resources of the interface A in the LCLS info Cnf message; after receiving the LCLS info Cnf message from the MSC-B center, the MSC-A center instructs the BSC controller to disconnect the local switch, and then notifies the MSC-B center that the local switch is already disconnected via the LCLS info Req request after that as the switch to local reception is disconnected. It should be noted that if the MSC-A center cannot request the BSC controller to disconnect the switch to local reception, then the MSC-A center must also inform the MSC-B center through an LCLS info Req request, so that the MSC-A center and the MSC-B center free A interface resources that they have already accessed.

Of course, in addition to the previous case, in which the MSC subscriber center, for example, the MSC-A center, requests the BSC controller to disconnect the switch to local reception, both MSC centers of both call subscribers, that is, the MSC-A center and the MSC-B center, can request the BSC controller to disconnect the switch to local reception. For example, the details may be as follows:

When the MSC-A center needs to disconnect the switch to local reception due to the occurrence of operations such as an additional service, the MSC-A center asks for access to the interface resources A from the MGW of the gateway according to the local switch information for the two call subscribers; if the MSC-A center successfully gained access to the resources of the interface A, the MSC-A center sends an LCLS info Req request to the MSC-B center, notifies the MSC-B center and asks the MSC-B center to disconnect the local switch; after the MSC-B center receives the LCLS info Req request, the MSC-B center accesses the interface resources A from the MGW of the gateway, and returns the LCLS info Cnf message to the MSC-A center, and the LCLS info Cnf message does not carry resource A information interface. In addition, the MSC-B center instructs the BSC controller to disconnect the local receive switch, and returns an LCLS info Cnf message to notify the MSC-A center that the local receive switch is already disconnected; after receiving the LCLS info Cnf message, the MSC-A center instructs the BSC controller to disconnect the switch to local reception.

Of course, the MSC-A center can also directly request the MSC-B center to disconnect the switch to local reception; after receiving the request, the MSC-B center asks for access to the resources of the interface A from the MGW gateway, if the MSC-B center has successfully accessed the resources of the interface A, then it returns to the MSC-A center the message LCLS info Cnf to inform the MSC-A center ; after receiving the LCLS info Cnf message, the MSC-A center gains access to the interface resources A from the MGW gateway; if the MSC-A center cannot access the resources of the interface A, then the MSC-A center does not disconnect the switch to local reception; if the MSC-A center has successfully gained access to the resources of the interface A, the MSC-A center instructs the BSC controller to disconnect the switch to local reception; if the MSC-B center cannot access the resources of the interface A, then the MSC-B center can return the message "rejected" to the MSC-A center; after receiving the “rejected” message, the MSC-A center does not disconnect the switch to local reception. The MSC-A center may perform various processing according to various reasons for initiating a disconnection of a local reception switch. For example, if an additional service occurs, then the MSC-A center rejects the additional service; if permitted interception is performed, then the MSC-A center may disconnect the call, or not intercept the call.

3. Scenario 3: Setting the switch to local reception during the control transfer process

Switching to local reception is not established during a call. However, after the transfer of control, both the calling subscriber and the called subscriber belong to the same BSC controller, and both subscribers have the ability to start switching to local reception. In this case, a switch to local reception should be set. That is, when one user transfers control of the BSC to the controller of another user and the conditions for starting switching to local reception are satisfied, switching to local reception should be established.

The following describes the method of setting the switch to local reception when there is a transfer of control between BSC controllers in relation to one subscriber during an inter-office call. Control transfer between BSC controllers includes intra-office transfer of control between BSC controllers and inter-office transfer of control between BSC controllers. It is assumed that the BSC controller before the transfer of control is the source BSC controller, and the BSC controller after the transfer of control is the final BSC controller. The source BSC controller is designated as BSC1 and the target BSC controller is designated as BSC2.

Next, a scenario is first described in which an intra-office transfer of control between BSC controllers occurs with respect to the caller during an inter-office call. As shown in figure 3, a specific process includes the following steps:

B201: The BSC1 controller sends a control transfer request to the MSC-A center, and the MSC-A center sends an ADD_REQ request to the MGW gateway. The MGW gateway may return an ADD_REPLY response to the MSC-A center.

B202: The MSC-A center sends a control transfer request to the BSC2 controller, wherein the control transfer request carries LS ind (local switch indication), for example, indicating that the BSC2 controller has started or disconnected the local switch.

For example, the MSC-A center can evaluate whether the MSC-B center has the ability to start switching to local reception according to information exchanged between the MSC-A center and the MSC-B center during the call setup phase and during the call process, for example, call information switching to local reception of the MSC-B center; if the MSC-B center has the ability to start switching to local reception, then the MSC-A center sends a control transfer request to the BSC2 controller, and the control transfer request may indicate that the BSC2 controller starts switching to local reception and carries a Call-ID identifier after transmission management; if the MSC-B center does not have the ability to start switching to local reception, then the control transfer request sent to the BSC2 controller does not show the beginning of switching to local reception.

The BSC2 controller can return a Handover Request ack acknowledgment, which carries the local receive switch acknowledgment (LS ack) to the MSC-A center.

B203: The MSC-A center sends a control transfer command to the BSC1 controller.

B204: The BSC2 controller sends to the MSC-A center a control transfer detection message and control transfer complete.

B205: The MSC-A center sends a reset command to the BSC1 controller, and the BSC1 controller returns a reset complete message to the MSC-A center.

B206: The MSC-A center sends an LCLS info Req request to the MSC-B center to start switching to local reception, and the LCLS info Req request carries information of the BSC signaling node of the calling party controller, the corresponding Call-ID, and an indication indicating that the switch the local reception has already begun. The MSC-B Center may return LCLS info Cnf approval to the MSC-A Center. Then, if the conditions for the start of switching to local reception are satisfied, the MSC-A center notifies the BSC controller in the area of which the MS-A terminal is located, the start of switching to local reception, and notifies the MGW gateway about the release of resources A of the MS-A terminal interface . In this case, the MSC-B center also notifies the BSC controller, in the area of which the MS-B terminal is located, of the start of switching to local reception, and notifies the MGW of the gateway about the release of resources A of the MS-B terminal interface. You can refer to the associated descriptions of the first scenario for a method of disconnecting the switch to local reception, which are not described again here.

The following describes a scenario in which an interoffice transfer of control between BSC controllers occurs with respect to a user during an interoffice call. That is, in this MSC scenario, the center of the source BSC controller is different from that of the final BSC controller. It is assumed that the interoffice transfer of control between BSC controllers occurs with respect to the caller, that the source MSC center is the MSC-A center, the source BSC controller is the BSC1 controller, the final MSC center is the MSC-A 'center, the final BSC controller is the BSC2 controller, MSC the center of the called party is the MSC-B center, and the BSC controller of the called party is the BSC2 controller. As shown in FIG. 4, a specific process includes the following steps:

C201: After the MSC-A center receives a control transfer request, if the MSC-A center concludes that a switch to local reception can be started, for example, the MSC-A center determines, according to the local switch information, both call subscribers Since both subscribers of the call have the ability to start switching to local reception, the control transfer request sent to the MSC-A center carries an indication indicating that the switching to local reception has begun. Thus, after completion of the control transfer, the MSC-A 'center notifies the MGW gateway of the release of resources A of the local subscriber interface, according to the indication that the switch to local reception has begun, and notifies the BSC controller of the start of switching to local reception. The MSC-A 'center returns a control transmission response to the MSC-A center indicating that the switch to local reception has begun successfully, and the control transfer request sent to the MSC-A' center may be a control transfer request prepared by the MAP subsystem.

C202: The MSC-A 'center sends a control transfer request to the BSC2 controller, and the control transfer request carries an indication LS ind, for example, indicating that the BSC2 controller starts or disconnects the switch to local reception, and the Call-ID is the call identifier after the transfer of control. The BSC2 controller can return a control transfer request acknowledgment that carries an LS ack acknowledgment to the MSC-A 'center.

C203: The MSC-A center sends to the MSC-A center a control transfer request acknowledgment that carries an LS ack confirmation, the control transfer acknowledgment may be a control transfer response prepared by the MAP subsystem.

C204: After completion of the control transfer, the MSC-A 'center autonomously notifies the MGW gateway of the release of the corresponding transmission channel A of the interface. The MSC-A center and / or MSC-B center notifies the BSC controller of the start of a switch to local reception. The process between the MSC-A center and / or the MSC-B center is the same as the process formed when an intra-office transfer of control between BSC controllers occurs with respect to the subscriber, for example, the MSC-A center sends an LCLS info Req request to the MSC-B center, and the MSC-B center returns LCLS info Cnf approval to the MSC-A center, and the MSC-B center notifies the MGW gateway of the release of A interface resources. You can refer to the previous options for implementation for details that are not repeatedly described here.

Of course, in addition to the MSC-A center, the MSC-A 'center can also evaluate whether switching to local reception has begun. Details are described below:

After completion of the interoffice control transfer, the MSC-A center always sends to the MSC-A 'center switching information to the local reception, regardless of whether the switching to local reception has begun. For example, the MSC-A center notifies the MSC-A 'center of the possibility of switching to local call reception, the information of the signaling node of the BSC controller in which the MSC-B center is located, and the Call-ID, so that the final MSC center performs switching processing to local reception according to switching information to local reception of both the calling subscriber and the called subscriber. In addition, in subsequent call processes, if the information of the possibility of switching to local call reception or the information of the signaling node of the BSC of the controller in which the MSC-B center is located changes, the MSC-A center can always notify the MSC-A 'center of such changes.

The following describes the verification process and the start of switching to local reception, formed when there is an intra-office transfer of control in relation to the user after the completion of inter-office transfer of control. That is, if the calling subscriber and the called subscriber do not belong to the same BSC controller, and the switch to local reception does not start after the occurrence of interoffice control transfer, then the intra-office cross control transfer between BSC controllers occurs subsequently in relation to the user inside the MSC-A 'center. If one subscriber of the call transfers control to the BSC to the controller in the area of which the other subscriber of the call is located, switching to local reception can be started.

After the MSC-A 'center receives the control transfer request, the MSC-A' center first sends an LCLS info Req request, which carries the control transfer information from the final BSC controller of the MSC-A to the center, so that it can be determined whether switching to local reception. If the MSC-A center concludes that switching to the local reception can be started, then the MSC-A center returns to the MSC-A 'center an indication that the start of switching to local reception is allowed. The MSC-A 'center continues to carry out a subsequent transfer of control and begins switching to local reception. Reference may be made to the previous embodiments for details. After completion of the control transfer, the MSC-A 'center shall inform the MSC-A center that the switch to local reception has already begun. The MSC-A center shall transmit to the MSC-B center the information for switching to the local reception of the MSC-A 'center.

Of course, the MSC-A 'center can autonomously evaluate whether switching to local reception can be started. That is, after receiving the MSC-A 'control transfer request, the center autonomously evaluates whether switching to local reception can be started; if switching to local reception can be started, then the MSC-A 'center starts switching to local reception during the transfer of control. After the transfer of control is completed, the MSC-A 'center notifies the MSC-A center that the switch to local reception has already begun, and that the MSC-A center should transmit the switching information to the local reception of the MSC-A' center in the MSC-B center.

It should be noted that in an MSC POOL network, after a cross-control transfer occurs between BSC controllers in relation to one call subscriber, the MSC center in the zone of which one call subscriber must also notify the MSC center in the zone of which the peer is located , about the information of the new BSC controller, even if the switch to local reception did not start.

4. Scenario 4: Disconnect the switch to local reception during the control transfer process.

Next, a process is described first in which the switch to local reception is disconnected when an intra-office transfer of control between BSC controllers occurs with respect to the user during an inter-office call. Details are as follows:

When the MSC-A center receives the control transfer request and concludes, according to the received control transfer request, that the switch to local reception needs to be disconnected, the MSC-A center sends to the MSC-B center a disconnect request to switch to local reception, for example, the MSC-A center sends LCLS info Req request to MSC-B center; after receiving the LCLS info Req request, the MSC-B center can evaluate whether the switch to local reception can be disconnected according to the request to disconnect the switch to local reception; if the switch to local reception cannot be disconnected, then the MSC-B center returns a message “rejected” to the MSC-A center; after receiving the message "rejected", the MSC-A center rejects the transfer of control; if the switch to local reception can be disconnected, then the MSC-B center requests access to the interface resources A from the MGW of the gateway and returns a confirmation (ACK) to the MSC-A center indicating that access to the interface resources A has been successfully obtained, for example, MSC- The B center returns the LCLS info Cnf statement to the MSC-A center, and the LCLS info Cnf statement carries information of interface A resources to which the MSC-B center has accessed from the MGW gateway; after receiving the LCLS info Cnf approval, the MSC-A center asks for access to the interface resources A from the MGW gateway, notifies the BSC controller of the disconnection of switching to local reception, and performs subsequent processing of the control transfer. In addition, the MSC-A center transmits an indication of the disconnection of switching to local reception and information of resources of the interface A to which the MSC-B center has accessed, in a control transfer command sent by the source BSC controller; after completion of the control transfer, the MSC-A center notifies the MSC-B center that the switch to local reception has already been disconnected.

Of course, the MSC-A center can also send an LCLS info Req request to the MSC-B center after gaining access to the interface resources A from the MGW gateway. That is, the MSC-A center first requests access to the resources of the interface A from the MGW gateway and then sends an LCLS info Req request to the MSC-B center after it has successfully accessed the resources of the interface A.

In addition, in addition to the previous case in which the MSC subscriber center, for example, the MSC-A center, instructs the BSC controller to disconnect the switch to local reception, the MSC centers of both call subscribers, that is, the MSC-A center and the MSC-B center, can instruct their respective BSC controllers to disconnect switching to local reception. Details may be as follows:

When the MSC-A center receives the control transfer request and concludes, according to the received control transfer request, that the switch to local reception needs to be disconnected, the MSC-A center sends to the MSC-B center a disconnect request to switch to local reception, for example, the MSC-A center sends LCLS info Req request to MSC-B center; after receiving the LCLS info Req request, the MSC-B center evaluates, according to the LCLS info Req request, whether the disconnection of switching to local reception is allowed; if LS disconnection is not allowed, then the MSC-B center returns a “rejected” message to the MSC-A center; after receiving the message "rejected", the MSC-A center rejects the transfer of control; if LS disconnection is enabled, then the MSC-B center asks for access to interface resources A from the MGW of the gateway and returns to the MSC-A center an indication of LS disconnection permission (not carrying information about access to resources of the interface A); The MSC-A center performs, according to the indication of the release resolution LS, the subsequent control transfer processing, including information on accessing the resources of the interface A from the MGW of the gateway, and notifying the BSC of the disconnection of the switch to local reception. After completion of the control transfer, the MSC-A center sends a notification to the MSC-B center indicating that the switch to local reception has already been disconnected; The MSC-B center disconnects the local receive switch according to a notification indicating that the local receive switch is already disconnected, and returns an acknowledgment (ACK) to the MSC-A.

Of course, the MSC-A center can also request access to the interface A resources from the MGW gateway, and then send an LCLS info Req request to the MSC-B center. That is, the MSC-A center first requests access to the interface resources A from the MGW gateway, and then sends the LCLS info Req request to the MSC-B center after it has successfully accessed the interface resources A.

When switching to local reception needs to be disconnected due to the occurrence of interoffice control transfer between BSC controllers in relation to the user, the interaction and intra-office control transfer between the MSC-A center and the MSC-B center are the same as in the previous description, and are not described again here. It should be noted that before performing the control transfer, the MSC-A 'center must obtain permission from the MSC-A center and the MSC-B center.

From the preceding description, it can be understood that in this embodiment, local switchover information is exchanged between MSC centers using MAP signaling, so that MSC centers can perform local switchover processing according to the local switchover information (including local switchover information reception of both MSC-A center and MSC-B center). Thus, in the conditions of the MSC POOL network, even if the calling subscriber and the called subscriber are in the zone of different MSC centers, the MSC center in the zone of which the called subscriber is located, or the MSC center in which the called subscriber is located, can recognize the BSC controller, in the area of which the calling subscriber or the called subscriber is located, and evaluates whether to start switching to local reception, so as to perform switching processing to local reception. In addition, due to the fact that information on switching to local reception can be transmitted between MSC centers via MAP signaling, if switching to local reception cannot be started due to the fact that the call is intercepted or operations are performed on one MSC center such as Alert or additional service, another MSC center may know details that facilitate the switch to local reception. Moreover, if the information of switching to the local reception is transmitted between the MSC centers through the MAP signaling, then for the MSC center there is no need to make unnecessary changes that contribute to the specified implementation.

OPTION 3

According to the method provided in Embodiment 1 of the present invention, this embodiment describes how to switch to local reception by exchanging local switch information between MSC centers via a trunk signaling. The solution is illustrated as follows:

1. The MSC center of the calling subscriber exchanges information with the MSC center of the called subscriber through the trunk signaling.

The MSC center of a certain subscriber sends the switching information to the local reception of the local subscriber to the MSC center of the equal subscriber using the trunk signaling, and the switching information to the local reception includes information of the signaling node of the BSC of the controller in which the local call branch is located, and / or switching capability information at the local reception. After receiving the switching information to the local reception of the local subscriber, the MSC center of the equal subscriber stores the received switching information to the local reception of the MSC center of the local subscriber, and returns to the MSC center the information of switching to the local reception of the equal subscriber using the trunk signaling. If the switching information to the local reception of the MSC center of a certain subscriber changes during the call, then the MSC center of the local subscriber needs to send the changed information of switching to local reception to the MSC center of the peer, so as to ensure that the MSC centers of both the calling subscriber and the called subscriber each other’s information at the same time, and the switching process to the local reception is performed according to the complete information of switching to the local reception, that is, information of switching to the local reception boih MSC centers.

2. The previous trunk signaling used to transfer the switching information to local reception can be achieved using the following trunk signaling, such as: Independent Transmission Call Control Protocol (BICC), or Session Initiation Protocol (SIP), or subscriber signaling subsystem for integrated service digital network (ISUP). Previous trunk signaling can also be achieved by expanding the current trunk signaling.

For example, an information request (INR) or information (INF), which is the current BICC message, or INR request and INF information, which is the current ISUP message, can be expanded.

SIP signaling can use SIP-I signaling. In addition, information (INFO) can be used to carry the extended INR request of the ISUP subsystem. The 200 OK response message may be used to carry the extended INF information of the ISUP message, so that local switch information is transmitted between the MSC center of the calling subscriber and the MSC center of the called subscriber.

Extended INR request and INF information can carry the following information:

(1) Information of the signaling node of the BSC controller where the call subscriber is located inside the local office.

(2) Indication of switching to local reception LS ind, which can be used to transmit information about the possibility of switching to local reception of the call subscriber inside the local office at the first MSC center or second MSC center. For example, the following types of indications can be used:

Local Call Local Call Reception Request (LCLS ADD_REQ), LCLS switching is enabled, LCLS switching is denied, LCLS switching is denied, LCLS switching is denied, LCLS switching is denied, LCLS switching is indicated, LCLS switching is set, and LCLS is disconnected switching.

(3) Call-ID - call identification number within the local office. The call leg is identified using a Call-ID identifier between the MSC center and the BSC controller.

(4) Transmission channel information A interface inside the local office. When the BSC controller disconnects the local switch, the channel information A of the interface of the two call branches should be used. In addition, in addition to the previous case in which the MSC of the caller exchanges local switch information with the MSC of the called subscriber by extending the trunk signaling, the MSC of the caller can also exchange local switch information with the MSC of the called subscriber by adding trunk signaling. For example, LCLS request and LCLS information related to the BICC message are added, or LCLS request and LCLS information related to the ISUP message are added. It should be noted that the signaling name is provided only as an example, and it can be understood that other signaling names are also applicable. SIP signaling can use SIP-I signaling. In addition, INFO information may be used to carry the added LCLS ISUP request message. The 200 OK message can be used to carry the LCLS-added ISUP message information, so that local switch information is transmitted between the MSC center of the calling subscriber and the MSC center of the called subscriber.

For simplicity, in this embodiment, the fact that SIP signaling is expanding is taken as an example to illustrate.

The solution is described in detail below with reference to several specific scenarios. For simplicity, the following description is based on the assumption that the calling terminal is designated MS-A, the MSC of the calling party is indicated by MSC-A, the called terminal is indicated by MS-B, and the MSC of the called party is indicated by MSC-B.

1. Scenario 1: Call setup process

During the call setup, the MSC centers of both the calling subscriber and the called subscriber, that is, MSC-A and MSC-B, transmit their respective local switch information via the extended SIP signaling. INFO information may be used to carry the extended INR request of the ISUP message, and 200 OK message may be used to carry the extended INR request of the ISUP message. As shown in FIGS. 5A and 5B, a specific process may include the following steps:

A301: The MS-A terminal sends a CM service request to the MSC-A center.

A302: The MSC-A center performs authentication and encryption with respect to the MS-A terminal, for example, the MSC-A center exchanges an authentication and encryption message with the MS-A terminal.

A303: The MS-A terminal sends a setup message to the MSC-A center, and the MSC-A center returns a call continue message to the MS-A terminal.

A304: The MSC-A center sends an ADD_REQ request to the MGW gateway, and the MGW gateway returns an ADD_REPLY response to the MSC-A center.

A305: MSC-A center sends ASS_REQ request to BSC; The BSC controller sends the ASS_CMD command to the MS-A terminal; The MS-A terminal returns an ASS_COMP message to the BSC controller; The BSC controller returns the ASS_RSP response to the MSC-A center.

A306: The MSC-A center sends routing information (SRI) to the HLR register to request the routing information of the MS-B terminal.

A307: The HLR register sends a PRN request to the MSC-B to receive the roaming number of the caller.

A308: The MSC-B center returns a confirmation PRN ack to the HLR register.

A309: The HLR register returns an SRI ack confirmation to the MSC-A center.

A310: The MSC-A center again sends an ADD_REQ request to the MGW gateway, and the MGW gateway returns an ADD_REPLY response to the MSC-A center.

A311: The MSC-A center sends a start address (IAM) message to the MSC-B center, and the MSC-B center sends a page to the BSC controller, the BSC controller sends a page to the MS-B terminal, and the MS-B terminal can return to the BSC controller response to the page (Page rsp); after receiving the Page rsp response, the controller can send the Page rsp response to the MSC-B center.

A312: The MSC-B center performs authentication and encryption with respect to the MS-B terminal, for example, the MSC-B center exchanges an authentication and encryption message with the MS-B terminal. In addition, the MSC-B center sends an ADD_REQ request to the MGW gateway, and the MGW gateway returns an ADD_REPLY response to the MSC-B center; The MSC-B center sends a setup message to the MS-B terminal, and the MS-B terminal returns a Call Confirmed message to the MSC-B center.

A313: The MSC-B center again sends an ADD_REQ request to the MGW gateway, and the MGW gateway returns an ADD_REPLY response to the MSC-B center.

A314: The MSC-B center sends an ASS_REQ request to the BSC; The BSC controller sends the ASS_CMD command to the MS-B terminal; The MS-B terminal returns an ASS_COMP message to the BSC controller; The BSC controller returns the ASS_RSP response to the MSC-B center.

A315: The MS-B terminal can send an ALERT (alarm) message to the MSC-B center; The MSC-B center sends the final address message (ACM) to the MSC-A center; The MSC-A center sends an ALTERT alarm message to the MS-A terminal. Then, the MS-B terminal sends a CONNECT (connection) message to the MSC-B center, and the MSC-B center can return a CONNECT_ACK (connection confirmation) message to the MS-B terminal; The MSC-B center sends a response message (ANM) to the MSC-A center; The MSC-A center sends a CONNECT connection message to the MS-A terminal, and the MS-A terminal can return a CONNECT_ACK (connection confirmation) message to the MSC-A center. By this time, the call setup process between the MS-A terminal and the MS-B terminal is completed.

A316: the MSC-B center sends to the MSC-A center the INFO [INR] information request message, the INFO [INR] information request message carries information of the signaling node of the BSC controller where the MS-B terminal is located, information on the possibility of switching to local MSC- reception Center B and Call-ID (call identifier) of the MS-B terminal.

A317: The MSC-A center evaluates whether the conditions for initiating a switch to local reception are met; if the conditions for the start of switching to local reception are satisfied, then the MSC-A center starts switching to local reception, that is, step A318 is performed.

For example, the MSC-A center determines, according to the information of the signaling node of the BSC controller in which the MS-A terminal is located, and the information of the signaling node of the BSC controller in which the MS-B terminal is located, both call subscribers belong to the same BSC controller.

If both subscribers of the call belong to one BSC controller, then the MSC-A center determines, according to the information of the possibility of switching to local reception of the MSC-A center and the information of the possibility of switching to local reception of the MSC-B center, that both subscribers of the call have the ability to start switching to local reception (for example, the encoding and decoding of the calling subscriber and the called subscriber are the same; the BSC controller of the called subscriber supports switching to local reception, and the caller is not eavesdropped). In this case, the MSC-A center notifies the BSC controller, in the area of which the MS-A terminal is located, of the start of switching to local reception (step A318), and notifies the MGW of the gateway about the release of resources A of the terminal MS-A interface (step A319). If the MSC-A center determines that the local office is not able to start switching to local reception, then a 200 OK [INF] message returned to the MSC-B center indicates that switching to local reception is not allowed. After the MSC-B center receives the 200 OK [INF] message, if the 200 OK [INF] message indicates that switching to local reception is not allowed, then switching to local reception cannot be started.

If the MSC-A center does not have a restriction to start switching to local reception, but the MS-A terminal and the MS-B terminal do not belong to the same BSC controller, then the MSC-A center returns 200 OK [INF] directly to the MSC-B center moreover, the 200 OK [INF] message carries information of the BSC signaling node of the terminal controller MS-A and the corresponding Call-ID identifier.

In the present embodiment, assuming that the MS-A center and the MS-B center belong to one BSC controller, and that both the MS-A center and the MS-B center have the ability to start switching to local reception, the MSC-A center starts switching to local reception after receiving a 200 OK [INF] message sent from the MSC-B center, that is, step A318 is performed.

A318: The MSC-A center sends to the BSC controller a local switching command LOCAL SWITCH COMMAND to start switching to local reception, the BSC controller returns a LOCAL SWITCH COMP message to the MSC-A center; The MSC-A center returns to the MSC-B center a 200 OK [INF] message, the 200 OK [INF] message carries the BSC signaling node information of the center MS-A controller and the corresponding Call-ID identifier, and indicates that the switch to local reception is already started.

It should be noted that if the BSC controller could not start switching to local reception, then the MSC-A center carries the information of the BSC signaling node of the MS-A terminal controller in a 200 OK [INF] message, returning a 200 OK [INF] message to the MSC-B center , and shows that the switch to local reception has not started.

A319: The MSC-A center sends a SUB_REQ request to the MGW gateway to release A resources of the MS-A interface of the terminal. The MGW gateway may return a SUB_REPLY response to the MSC-A center.

A320: After the MSC-B center receives the 200 OK [INF] message returned from the MSC-A center, if the 200 OK [INF] message indicates that the switch to local reception has already begun, the MSC-B center sends to the MGW gateway request SUB_REQ to free resources of the terminal MS-B interface A. The MGW gateway may return a SUB_REPLY response to the MSC-B center. If the 200 OK [INF] message indicates that the switch to local reception has not begun, then the MSC-B center does not perform operations.

By this time, the installation of switching to the local reception is completed. It should be noted that the MAP connection should not be supported between the MSC center of the calling party and the MSC center of the called party, that is, between the MSC-A center and the MSC-B center. In addition, after the switch to local reception has begun, trunk resources between the MSC-A center and the MSC-B center are not released. This is because switching to local reception, which is already installed, cannot be disconnected if trunk resources are freed.

Of course, the INFO [INF] message may be initiated by the MSC-A center first. The execution method is similar to the above method, in which the MSC-B center first initiates the INFO [INF] message. That is, after the MSC-B center receives the INFO [INF] message sent from the MSC-A center, the MSC-B center determines whether both call subscribers belong to the same BSC controller according to the information of the signaling node of the BSC controller in which the MS is located -A terminal, and information of the signaling node of the BSC controller in which the MS-B terminal is located; if both subscribers of the call belong to the same BSC controller, then the MSC-B center determines, according to the information of the possibility of switching to local reception of the MSC-A center and information of the possibility of switching to local reception of the MSC-B center, that both subscribers of the call have the ability to start switching to local reception (for example, the encoding and decoding of the calling subscriber and the called subscriber are the same; the BSC controller of the called subscriber supports switching to local reception, and the caller is not eavesdropped). In this case, the MSC-B center notifies the BSC controller, in the area of which the MS-B terminal is located, of the start of switching to local reception, and notifies the MGW of the gateway about the release of resources A of the MS-B interface of the terminal. In addition, the MSC-B center also returns a 200 OK [INF] message to the MSC-A center, the 200 OK [INF] message carries information of the BSC signaling node of the center controller MS-B and the corresponding Call-ID identifier, and indicates that the switching the local reception has already begun. If the MSC-B center determines that the local office is not able to start switching to local reception, then the 200 OK [INF] message returned to the MSC-A center indicates that switching to local reception is not allowed. After the MSC-A center receives a 200 OK [INF] message, if the 200 OK [INF] message indicates that switching to local reception is not allowed, then the MSC-A center does not start switching to local reception. If the MSC-B center does not have restrictions to start switching to local reception, but the MS-A terminal and the MS-B terminal do not belong to the same BSC controller, then the MSC-B center returns 200 OK [INF] directly to the MSC-A center moreover, the 200 OK [INF] message carries information of the BSC signaling node of the terminal controller MS-B and the corresponding Call-ID identifier.

In addition, it should be noted that in addition to the previous case, in which the MSC of the subscriber center makes an assessment and starts switching to local reception, both the MSC center of the caller and the MSC center of the called subscriber can also make an assessment and start switching to local reception. For example, after step A316, the MSC-A center may return a 200 OK [INF] message to the MSC-B center, the MSC-A center and the MSC-B center evaluate whether the appropriate conditions to start switching to local reception are satisfied; if their respective conditions for starting switching to local reception are satisfied, then the MSC-A center and the MSC-B center begin switching to local reception, respectively. That is, on the one hand, the MSC-A center notifies the BSC controller in the area of which the MS-A terminal is located, of the start of switching to local reception, and notifies the MGW of the gateway about the release of resources A of the terminal MS-A interface; on the other hand, the MSC-B center also notifies the BSC controller, in the area of which the MS-B terminal is located, of the start of switching to local reception, and notifies the MGW of the gateway about the release of resources A of the MS-B terminal interface.

During a call, the MSC-A center and the MSC-B center can update the local switch reception information by using the INFO [INR] message and the 200 OK [INF] message. That is, when the information of the possibility of switching to local call reception changes, the MSC-A center must interact dynamically with the MSC-B center. For example, when a call is initiated, the switch to local reception does not start, because the MS-A terminal and the MS-B terminal do not belong to the same BSC controller. However, there are no other restrictions on switching to local reception. In the current call process, if the user of the MS-A terminal is eavesdropping or an additional service occurs, the MSC-A center must notify the MSC-B center that the call does not have the ability to switch to local reception; if the eavesdropping subsequently ends or the additional service ends, the MSC-A center must notify the MSC-B center that the call has the ability to switch to local reception. When a call does not have the ability to switch to local reception, even if both the calling subscriber and the called subscriber belong to the same BSC controller, switching to local reception does not start.

2. Scenario 2: After setting the switch to local reception, the MSC center requests the disconnect switch to local reception.

When the switch to local reception has to be disconnected due to the occurrence of operations such as an additional service in the MSC-A center, the MSC-A center asks for access to the interface resources A from the MGW of the gateway according to the local switch information for both the calling subscriber and the called subscriber; if the MSC-A center has successfully accessed the resources of the interface A, it sends an INFO [INR] message to the MSC-B center, notifies the MSC-B center and requests the MSC-B center to disconnect the local switch. After receiving the INFO [INR] message, the MSC-B center requests access to the interface resources A from the MGW gateway; if the MSC-B center successfully gained access to the resources of the interface A, then it returns to the MSC-A center the message 200 OK [INF], and transmits the corresponding resources of the interface A in the message 200 OK [INF]. After receiving a 200 OK [INF] message from the MSC-B center, the MSC-A center instructs the BSC controller to disconnect the local switch; after the switch to local reception is disconnected, the MSC-A center informs the MSC-B center that the switch to local reception is already disconnected, via the INFO [INR] message. It should be noted that if the MSC-A center cannot request the BSC controller to disconnect the switch to local reception, then the MSC-A center must also inform the MSC-B center via the INFO [INR] message, so that the MSC-A center and MSC-B the center frees up A interface resources to which they have already accessed.

Of course, in addition to the previous case, in which the MSC subscriber center, for example, the MSC-A center, requests the BSC controller to disconnect the switch to local reception, both MSC centers of both call subscribers, that is, the MSC-A center and the MSC-B center, can request the BSC controller to disconnect the switch to local reception. For example, the details may be as follows:

When the switch to local reception has to be disconnected due to the occurrence of operations such as an additional service in the MSC-A center, the MSC-A center asks for access to the interface resources A from the MGW of the gateway according to the local switch information for both the calling subscriber and the called subscriber; if the MSC-A center has successfully gained access to the resources of the interface A, the MSC-A center sends an INFO [INR] message to the MSC-B center, notifies the MSC-B center and requests a disconnection of the switch to local reception. After receiving a 200 OK [INF] message, the MSC-B center requests access to the interface resources A from the MGW of the gateway, and returns a 200 OK [INF] message to the MSC-A center, and the 200 OK [INF] message does not carry the resource information A of the interface . In addition, the MSC-B center instructs the BSC controller to disconnect the local switch, and returns a 200 OK [INF] message to inform the MSC-A center that the local switch has already been disconnected; after receiving the 200 OK [INF] message, the MSC-A center instructs the BSC controller to disconnect the switch to local reception.

Of course, the MSC-A center can also directly request the MSC-B center to disconnect the switch to local reception; after receiving the request, the MSC-B center requests access to the resources of the interface A from the MGW gateway, if the MSC-B center has successfully accessed the resources of the interface A, then it returns to the MSC-A center the message LCLS info Cnf to inform the MSC-A center ; after receiving the LCLS info Cnf message, the MSC-A center gains access to the interface resources A from the MGW gateway; if the MSC-A center cannot access the resources of the A interface, then the switch to local reception is not disconnected; if the MSC-A center has successfully gained access to the resources of the interface A, the MSC-A center instructs the BSC controller to disconnect the switch to local reception; if the MSC-B center cannot access the resources of the interface A, then the MSC-B center can return the message "rejected" to the MSC-A center. After receiving the message “rejected”, the MSC-A center does not disconnect the switch to local reception. The MSC-A center may perform various processing according to various reasons for initiating a disconnection of a local reception switch. For example, if an additional service occurs, then the MSC-A center rejects the additional service; if permitted interception is performed, then the MSC-A center may disconnect the call, or not intercept the call.

3. Scenario 3: Setting the switch to local reception during the control transfer process

Switching to local reception is not established during a call. However, after the transfer of control, both the calling party and the called party belong to the same BSC controller, and both subscribers have the ability to start switching to local reception. In this case, a switch to local reception should be established. That is, when one user transfers control of the BSC to the controller of another user and the conditions for starting switching to local reception are satisfied, switching to local reception should be set.

The following describes the method of setting the switch to local reception when there is a transfer of control between BSC controllers in relation to one subscriber during an inter-office call. Control transfer between BSC controllers includes intra-office transfer of control between BSC controllers and inter-office transfer of control between BSC controllers. It is assumed that the BSC controller before the transfer of control is the source BSC controller, and the BSC controller after the transfer of control is the final BSC controller. The source BSC controller is designated as BSC1 and the target BSC controller is designated as BSC2.

Next, a scenario is first described in which an intra-office transfer of control between BSC controllers occurs with respect to the caller during an inter-office call. As shown in FIG. 6, a specific process includes the following steps:

B301: the BSC1 controller sends to the MSC-A center a request for a control transfer is required, and the MSC-A center sends an ADD_REQ request to the MGW gateway; and the MGW gateway may return an ADD_REPLY response to the MSC-A center.

B302: The MSC-A center sends a control transfer request to the BSC2 controller, the control transfer request being carried by LS ind (local switch indication), for example, indicating that the BSC2 controller has started or disconnected the local switch.

For example, the MSC-A center can evaluate whether the MSC-B center is able to start switching to local reception according to the relevant information exchanged between the MSC-A center and the MSC-B center during the call setup phase and during the call process, for example, information Possibility of switching to the local reception of the MSC-B center; if the MSC-B center has the ability to start switching to local reception, then the MSC-A center sends a control transfer request to the BSC2 controller, and the control transfer request may indicate that the BSC2 controller starts switching to local reception and carries a Call-ID identifier after transmission management; if the MSC-B center does not have the ability to start switching to local reception, then the control transfer request sent to the BSC2 controller does not show the beginning of switching to local reception.

The BSC2 controller can return a Handover Request ack acknowledgment, which carries a local receive acknowledgment (LS ack) to the MSC-A center.

B303: The MSC-A center sends a control transfer command to the BSC1 controller.

B304: The BSC2 controller sends a Handover Detect and Handover Complete message to the MSC-A Center.

B305: The MSC-A center sends a Clear Command to the BSC1 controller, and the BSC2 controller returns a Clear Complete message to the MSC-A center.

B306: The MSC-A center sends an INFO [INR] message to the MSC-B center to start switching to local reception, and the INFO [INR] message carries information of the BSC signaling node of the calling party controller, the corresponding Call-ID, and an indication showing that the switch to local reception has already begun. The MSC-B center can return a 200 OK [INR] message to the MSC-A center. Then, if the conditions for the start of switching to local reception are satisfied, the MSC-A center notifies the BSC controller in the area of which the MS-A terminal is located, the start of switching to local reception, and notifies the MGW gateway about the release of resources A of the MS-A terminal interface . In this case, the MSC-B center also notifies the BSC controller, in the area of which the MS-B terminal is located, of the start of switching to local reception, and notifies the MGW of the gateway about the release of resources A of the MS-B terminal interface. You can refer to the associated descriptions of the first scenario for a method of disconnecting the switch to local reception, which are not described again here.

The following describes a scenario in which an interoffice transfer of control between BSC controllers occurs with respect to a user during an interoffice call. That is, in this MSC scenario, the center of the source BSC controller is different from that of the final BSC controller. It is assumed that the interoffice transfer of control between BSC controllers occurs with respect to the caller, that the source MSC center is the MSC-A center, the source BSC controller is the BSC1 controller, the final MSC center is the MSC-A 'center, the final BSC controller is the BSC2 controller, MSC the center of the called party is the MSC-B center, and the BSC controller of the called party is the BSC2 controller. As shown in FIG. 7, a specific process includes the following steps:

C301: After the MSC-A center receives the control transfer request, if the MSC-A center concludes that the switch to local reception can be started, for example, the MSC-A center determines, according to the information of the possibility of switching to local reception of both call subscribers Since both call subscribers have the ability to start switching to local reception, the control transfer request sent to the MSC-A 'center carries an indication indicating that the switching to local reception has begun. Thus, after completion of the control transfer, the MSC-A 'center notifies the MGW gateway of the release of resources A of the local subscriber interface, and notifies the BSC controller of the start of switching to local reception, according to an indication that the switch to local reception has begun. The MSC-A center returns a control transfer response to the MSC-A center indicating that the switch to local reception has begun successfully, and the control transfer request sent to the MSC-A 'center may be a control transfer request prepared by the MAP subsystem.

C302: The MSC-A 'center sends a control transfer request to the BSC2 controller, and the control transfer request carries an indication LS ind, for example, indicating that the BSC2 controller starts or disconnects the switch to local reception, and the Call-ID is the call identifier after the transfer of control. The BSC2 controller may return a Handover Request ack acknowledgment, which carries an LS ack acknowledgment to the MSC-A 'center.

C303: The MSC-A 'center sends to the MSC-A center a control transfer request acknowledgment that carries an LS ack confirmation, the control transfer acknowledgment may be a control transfer response prepared by the MAP subsystem.

C304: After completion of the control transfer, the MSC-A 'center autonomously notifies the MGW gateway of the release of transmission channel A of the interface. The MSC-A center and / or MSC-B center notifies the BSC controller of the start of a switch to local reception. The process between the MSC-A center and the MSC-B center is the same as the process formed when an intra-office transfer of control between the BSC controllers occurs in relation to the user, for example, the MSC-A center sends an INFO [INR] message to the MSC-B center, and The MSC-B center returns a 200 OK [INR] message to the MSC-A center, and the MSC-B center notifies the MGW gateway of the release of A interface resources. You can refer to the previous options for implementation for details that are not repeatedly described here.

Of course, in addition to the MSC-A center, the MSC-A 'center can also evaluate whether switching to local reception has begun. Details are described below:

After completion of the interoffice control transfer, the MSC-A center always sends to the MSC-A 'center switching information to the local reception, regardless of whether the switching to local reception has begun. For example, the MSC-A center notifies the MSC-A 'center of the possibility of switching to local call reception, the information of the signaling node of the BSC controller in which the MSC-B center is located, and the Call-ID, so that the final MSC center performs switching processing to local reception according to switching information to local reception of both the calling subscriber and the called subscriber. In addition, in subsequent call processes, if the information of the possibility of switching to local call reception or the information of the signaling node of the BSC of the controller in which the MSC-B center is located changes, the MSC-A center can always notify the MSC-A 'center of such changes.

The following describes the verification process and the start of switching to local reception, formed when there is an intra-office transfer of control in relation to the user after the completion of inter-office transfer of control. That is, if the calling subscriber and the called subscriber do not belong to the same BSC controller, and the switch to local reception does not start after the occurrence of interoffice control transfer, then the intra-office cross control transfer between BSC controllers occurs subsequently in relation to the user inside the MSC-A 'center. If one subscriber of the call transfers control to the BSC to the controller in the area of which the other subscriber of the call is located, switching to local reception can be started.

After the MSC-A 'center receives the control transfer request, the MSC-A' center first sends an INFO [INR] message, which carries control transfer information from the final BSC of the MSC-A controller to the center, so as to determine whether switching can be started at the local reception. If the MSC-A center concludes that switching to the local reception can be started, then the MSC-A center returns to the MSC-A 'center an indication that the start of switching to local reception is allowed. The MSC-A 'center continues to carry out a subsequent transfer of control and begins switching to local reception. Reference may be made to the previous embodiments for details. After completion of the control transfer, the MSC-A 'center shall inform the MSC-A center that the switch to local reception has already begun. The MSC-A center shall transmit to the MSC-B center the information for switching to the local reception of the MSC-A 'center.

Of course, the MSC-A 'center can autonomously evaluate whether switching to local reception can be started. That is, after receiving the MSC-A 'control transfer request, the center autonomously evaluates whether switching to local reception can be started; if switching to local reception can be started, then the MSC-A 'center starts switching to local reception during the transfer of control. After the transfer of control is completed, the MSC-A 'center notifies the MSC-A center that the switch to local reception has already begun, and that the MSC-A center should transmit the switching information to the local reception of the MSC-A' center in the MSC-B center.

It should be noted that under the conditions of the MSC POOL network, after the control is cross-transmitted between BSC controllers in relation to one subscriber of the call, the MSC center in which the call is located must also notify the equal MSC center of the information of the new BSC controller if the switch to local reception does not start.

4. Scenario 4: Disconnect the switch to local reception during the control transfer process.

Next, a process is described first in which the switch to local reception is disconnected when an intra-office transfer of control between BSC controllers occurs with respect to the user during an inter-office call. Details are as follows:

When the MSC-A center receives the control transfer request and concludes, according to the received control transfer request, that the switch to local reception must be disconnected, the MSC-A center sends to the MSC-B center a disconnect request to switch to local reception, for example, the MSC-A center sends an INFO [INR] message to the MSC-B center; after receiving the INFO [INR] message, the MSC-B center may evaluate whether switching to local reception can be disconnected according to a request to disconnect switching to local reception; if the switch to local reception cannot be disconnected, then the MSC-B center returns a message “rejected” to the MSC-A center; after receiving the message "rejected", the MSC-A center rejects the transfer of control; if the switch to local reception can be disconnected, then the MSC-B center requests access to the interface resources A from the MGW of the gateway and returns a confirmation (ACK) to the MSC-A center indicating that access to the interface resources A has been successfully obtained, for example, MSC- The B center returns the LCLS info Cnf statement to the MSC-A center, and the LCLS info Cnf statement carries information of interface A resources to which the MSC-B center has accessed from the MGW gateway; after receiving the LCLS info Cnf approval, the MSC-A center asks for access to the interface resources A from the MGW gateway, notifies the BSC controller of the disconnection of switching to local reception, and performs subsequent processing of the control transfer. In addition, the MSC-A center transmits an LS Disconnect Indication indication and resource information A of the interface to which the MSC-B center has accessed, in a control transfer command sent to the source BSC controller; after completion of the control transfer, the MSC-A center notifies the MSC-B center that the switch to local reception has already been disconnected.

Of course, the MSC-A center can also request access to interface resources A from the MGW gateway, and then send an INFO [INR] message to the MSC-B center, that is, the MSC-A center requests access to interface resources A from the MGW gateway; The MSC-A center sends an INFO [INR] message to the MSC-B center only after it has successfully accessed the resources of the A interface.

In addition, in addition to the previous case in which the MSC subscriber center, for example, the MSC-A center, instructs the BSC controller to disconnect the switch to local reception, the MSC centers of both call subscribers, that is, the MSC-A center and the MSC-B center, can instruct their respective BSC controllers to disconnect switching to local reception. Details may be as follows:

When the MSC-A center receives the control transfer request and concludes, according to the received control transfer request, that the switch to local reception must be disconnected, the MSC-A center sends to the MSC-B center a disconnect request to switch to local reception, for example, the MSC-A center sends an INFO [INR] message to the MSC-B center; after receiving the INFO [INR] message, the MSC-B center judges, according to the INFO [INR] message, whether the disconnection of switching to local reception is allowed; if LS disconnection is not allowed, then the MSC-B center returns a “rejected” message to the MSC-A center; after receiving the message "rejected", the MSC-A center rejects the transfer of control; if LS disconnection is enabled, then the MSC-B center asks for access to interface resources A from the MGW of the gateway and returns to the MSC-A center an indication of LS disconnection permission (not carrying information about access to resources of the interface A); The MSC-A center performs, according to the indication of the release resolution LS, the subsequent control transfer processing, including information on accessing the resources of the interface A from the MGW of the gateway, and notifying the BSC of the disconnection of the switch to local reception. After completion of the control transfer, the MSC-A center sends a notification to the MSC-B center indicating that the switch to local reception has already been disconnected; The MSC-B center disconnects the local receive switch according to a notification indicating that the local switch has already been disconnected, and returns 200 OK [INF] to the MSC-A center.

Of course, the MSC-A center can also request access to the interface A resources from the MGW gateway, and then send an INFO [INR] message to the MSC-B center, that is, the MSC-A center requests access to the interface resources A from the MGW gateway; The MSC-A center sends an INFO [INR] message to the MSC-B center after it has successfully accessed the resources of the A interface.

When switching to local reception needs to be disconnected due to the occurrence of interoffice control transfer between BSC controllers in relation to the user, the interaction between the MSC-A center and the MSC-B center is the same as in the intra-office control transfer and is not described here again. It should be noted that before performing the control transfer, the MSC-A 'center must obtain permission from the MSC-A center and the MSC-B center.

From the foregoing description, it can be understood that in the aforementioned embodiment, local switching switching information is exchanged between MSC centers using trunk signaling, so that MSC centers can perform local switching switching processing according to the local switching switching information (including local switching information reception of both MSC-A center and MSC-B center). Thus, in the conditions of the MSC POOL network, even if the calling subscriber and the called subscriber are in the zone of different MSC centers, the MSC center in the zone of which the called subscriber is located can recognize the BSC controller, in the zone of which the called party or BSC controller is located, in the zone of which the called party is located. Therefore, an assessment can be made as to whether to begin switching to local reception, so as to perform switching processing to local reception. In addition, due to the fact that information on switching to local reception can be transmitted between MSC centers via the trunk signaling, if switching to local reception cannot be started due to the fact that the call is intercepted or operations are performed on one MSC center such as Alert or additional service, another MSC center may know details that facilitate the switch to local reception. Moreover, compared with the method for transferring local switch information between MSC centers using MAP signaling, using a trunk signaling to transfer local switch information between MSC centers does not require changing the HLR register, despite the many changes required with respect to MSC center (however, both the MSC center and the HLR register must be changed when local switch information is transferred between the MSC centers using MAP signaling).

OPTION 4

For a better implementation of the method provided in the previous embodiments, an embodiment of the present invention also provides an MSC center. As shown in FIG. 8, the MSC center includes a receiving unit 401 and a processing unit 402.

The receiving unit 401 is configured to receive local switch information for the peer of the call sent from the MSC of the peer of the call. For example, when both call subscribers are in the area of the first MSC center and the second MSC center, respectively, the first MSC center receives local switch information for the second call subscriber sent by the second MSC center. In particular, the first MSC center may receive switching information for local reception of the second call subscriber sent by the second MSC center via the MAP signaling or trunk signaling. The local reception switching information includes controller BSC information, for example, controller BSC signaling node information, and local reception switching information. Of course, the local switch information may also include other information required to set up and disconnect the local switch, for example, Call Call-ID and channel information A of the interface. The information of the signaling node of the BSC controller refers to the BSC controller in the area of which the call branch is located, while the information of the possibility of switching to local reception indicates whether there is a call pickup or whether operations such as notification or additional service are being performed.

The processing unit 402 is configured to perform local switch switching processing according to local switch switching information of the local subscriber and peer switching local information received by the receiving block 401, i.e., according to the local switch information of the first call subscriber and local switch information second caller of the call. Switching information for local reception of the first call subscriber or switching information for local reception of the second call subscriber includes controller BSC information in the area of which the first call subscriber or second call subscriber is located.

As shown in FIG. 8, the processing unit 402 may include a first evaluation subunit 4021 and a notification subunit 4023.

The first evaluation subunit 4021 is configured to evaluate whether both call subscribers belong to the same BSC controller, according to the local switch information of the local call subscriber and the local switch information of the peer call received by the receiving unit 401. That is, the first evaluation subunit 4021 evaluates whether both call subscribers belong to one BSC controller according to the BSC information of the first call subscriber controller and the BSC information of the second call subscriber controller received by the receiving unit 401.

The notification sub-block 4023 is configured to notify the BSC of the controller of the switchover to local reception and to notify the gateway MGW of the release of the local subscriber interface resources A, that is, the first subscriber interface resources A, when the first evaluation subunit 4021 determines that both call subscribers belong to the same BSC to the controller.

As shown in FIG. 8, the processing unit 402 may further include a second evaluation subunit 4022.

The second evaluation subunit 4022 is configured to evaluate whether both call subscribers are able to start switching to local reception, according to local switching information to local reception and peer information (i.e., the second call subscriber) can be switched to local reception 401 receipt.

The receiving unit 401 is further configured to receive local switch reception information of the second call subscriber when the local switch information of the first call subscriber or local switch information of the second call subscriber includes local switch information of the first call subscriber or second subscriber call.

The notification subunit 4023 is further configured to notify the BSC of the controller of the start of switching to local reception and to notify the gateway MGW of the release of the local subscriber interface resources A, that is, the first subscriber interface resources A, when the first evaluation subunit 4021 determines that both call subscribers are able to switching to local reception.

As shown in FIG. 8, the processing unit 402 may further include a first departure subunit 4024.

The first sending subunit 4024 is configured to send the switchover message ADD_REPLY to the peer MSC center, for example, to the second MSC center, so that the peer MSC, for example, the second, notifies the MGW of the release of resources A of the interface of the second peer of the call ( for example, call peer interface resources A), according to the local receive message ADD_REPLY.

As shown in FIG. 8, the processing unit 402 may further include an access subunit 4025.

The access obtaining subunit 4025 is configured to access the local subscriber interface resources A from the MGW of the gateway according to the local switch information for the local subscriber and the local switch information for the peer received by the receiving block 401. For example, the access obtaining subunit 4025 requests access to the resources of the local subscriber interface according to the local switch information of the first call subscriber and the local switch information of the second call subscriber received by the receiving unit.

The first sending subunit 4024 is further configured to send the local call switching disconnect request to the peer MSC center of the call (for example, the second MSC center), after successfully gaining access to the local call subscriber interface resources A block 4025 so that the peer MSC the call (for example, the second MSC center) gained access to resources A of the peer interface (i.e., resources A of the interface of the second call subscriber) from the MGW of the gateway according to the request Switch to local reception.

The notification sub-block 4023 is further configured to notify the BSC of the controller of the disconnection of the switch to local reception, after receiving an acknowledgment (ACK), which returns from the MSC of the peer of the call and indicates that access to the resources A of the interface of the peer of the call (i.e., the second call subscriber) received successfully.

As shown in FIG. 8, the processing unit 402 further includes a control transmission processing subunit 4026.

The control transmission processing subunit 4026 is configured so that when the second evaluation subunit 4022 determines that both call subscribers are able to start switching to local reception, transmit an indication indicating that the switching to local reception has begun in the control transfer request sent to the final MSC center, so that, after completion of the control transfer, the final MSC center notifies the MGW gateway about the release of resources A of the local call subscriber interface, notifies the BSC controller about the start of switching to the local reception according to an indication showing that the switch to local reception has started successfully, and then received a control transmission response that returns from the final MSC center and indicates that the switch to local reception has started successfully.

As shown in FIG. 8, the processing unit 402 further includes a second departure subunit 4027.

The second sending subunit 4027 is configured to send the switching information to the local reception of the local subscriber and the switching information to the local reception of the peer received by the receiving unit 401 to the final MSC center separately (i.e., the switching information to the local reception of the local subscriber and the switching information to the local peer reception the subscriber may not be sent at the same time), so that the final MSC center performs switching processing to local reception according to information switching to local receiving a local subscriber and switching information to the local receiving peer subscriber.

You can refer to the previous options for the implementation of the specific execution of the previous blocks, which are not discussed here again.

From the preceding description, it can be understood that in this embodiment, the MSC center receiving unit 401 may receive switching information for local peer-to-peer call reception sent by the MSC peer-to-peer call center; a processing unit 402 performs local switch switching processing according to local switch information of both the local call subscriber and the peer of the call. Thus, under MSC POOL network conditions, even if the calling subscriber and the called subscriber are in the zone of different MSC centers, the MSC center in the zone of which the calling subscriber is located, or the MSC center in the zone of which the called subscriber is located, can also recognize the BSC controller, in the area of which the calling subscriber or the called subscriber is located, and they can evaluate whether to switch to local reception, so as to perform switching processing to local reception. In addition, due to the fact that the receiving unit 401 can receive switching information to the local reception of the peer of the call sent by the MSC center of the peer of the call, if the switch to the local reception cannot be started due to the fact that the call is intercepted or such operations, such as alerts and additional services at one MSC center, another MSC center may know details that facilitate the switch to local reception.

OPTION 5

Accordingly, an embodiment of the present invention also provides a communication system including any MSC center provided in embodiments of the present invention. As shown in FIG. 9, the communication system may include a first MSC center 501 and a second MSC center 502.

The first MSC center is configured to, when both call subscribers are in the area of the first MSC center 501 and the second MSC center 502, respectively, to receive local switch information of the second call subscriber sent by the second MSC center 502, and perform local switch switching processing according to switching information to local reception of the first call subscriber and switching information to local reception of the second call subscriber, wherein switching information to local reception of the first call subscriber or switching information I on the local reception of the second call subscriber includes information of the BSC controller, in the area of which the first call subscriber or the second call subscriber is located.

The second MSC center 502 is configured to send switching information for local peer reception to the first MSC center 501.

The second MSC center 502 is further configured to send switching information for local reception of the second call subscriber to the first MSC center 501 via MAP signaling or trunk signaling. In addition to controller information, for example, controller BSC signaling node information, local reception switching information may also include local reception switching information. Of course, the local switch information may also include other information required to set up and disconnect the local switch, for example, Call Call-ID and channel information A of the interface. The information of the signaling node of the BSC controller refers to the BSC controller in the area of which the call branch is located, while the information of the possibility of switching to local reception indicates whether there is a call pickup or whether operations such as notification or additional service are being performed.

You can refer to the previous options for the implementation of the interaction between the first MSC center 501 and the second MSC center 502, which is not discussed again here.

From the foregoing description, it can be understood that in this embodiment, the MSC center in the communication system can receive local switch information of the peer of the call sent by the MSC peer center of the call, and then perform the local switch processing according to the local switch information of both local call subscriber and peer call subscriber. Thus, in the conditions of the MSC POOL network, even if the calling subscriber and the called subscriber are in the zone of different MSC centers, the MSC center in the zone of which the calling subscriber is located, or the MSC center in the zone of which the called subscriber can find, the zone of which the caller is located, or the BSC controller, in the zone of which the called subscriber, and they can evaluate whether to switch to local reception, so as to perform switching processing to local reception. In addition, due to the fact that the MSC center can receive information on switching to the local reception of the peer of the call sent from the MSC center of the peer of the call, if the switch to the local reception cannot be started due to the fact that the call is intercepted or such operations, such as notification and additional service at one MSC center, another MSC center may know such details that facilitate switching to local reception. In particular, local switch information can be transferred between MSC centers via MAP signaling or trunk signaling (refer to Embodiment 1 and Embodiment 2 for a detailed implementation method). When local switching information is transferred between MSC centers using MAP signaling, the MSC centers and the HLR register must be reformed, but only a few changes need to be made for MSC centers. When the information of switching to local reception is transferred between MSC centers using trunk signaling, changes are required only for MSC centers (it is not necessary to change the HLR register), but many changes need to be made for MSC centers. The specific method used to transfer the switching information to the local reception between the MSC centers can be selected according to the operator’s technique.

Those skilled in the art will appreciate that all or part of the steps of the methods of the preceding embodiments of the present invention can be performed using suitable hardware instructed by a certain program. The program may be stored in a computer readable medium. Computer-readable media can be read-only memory (ROM, ROM), random-access memory (RAM, RAM), a magnetic disk, or an optical disk.

The method for switching to local reception, the Mobile Switching Center (MSC), and the communication system provided in the embodiments of the present invention are described in detail above. Although the present invention has been described by way of certain specific embodiments, it is not limited to these embodiments. Professionals should be clear that various modifications and variations of the present invention can be made without going beyond and without deviating from the essence of the present invention. The present invention encompasses modifications and variations of the present invention that fall within the scope of the claims defined by the appended claims and their equivalents.

Claims (22)

1. A method of switching to a local reception, comprising:
when both call subscribers are in the zone of the first mobile switching center (MSC) and the second MSC center, respectively, receiving by the first MSC center, in the area of which the first call subscriber is located, information on switching to local reception of the second call subscriber sent by the second MSC center; and
execution by the first MSC of the local reception switching processing center according to local switching information of the first call subscriber and local switching information of the second call subscriber, wherein local switching information of the first call subscriber or local switching information of the second call subscriber contains information of the base controller station (BSC), in the area of which there is a corresponding first call subscriber or second call subscriber. 2. The method according to claim 1, in which the receiving, by the first MSC center, information of switching to local reception of the second subscriber of the call sent by the second MSC center, contains:
receiving, by the first MSC center, information on switching to local reception of the second subscriber of the call, which the second MSC center sends through the signaling of the mobile application subsystem (MAP) or trunk signaling. 3. The method according to claim 2, in which before the first MSC center receives information on switching to local reception of the second call subscriber, which the second MSC center sends through the MAP signaling, the method further comprises:
sending the first MSC center to the second MSC center of the local address and international local mobile number identification (IMSI) of the local call; and
receiving, by the first MSC center, local switching information of the second call subscriber that the second MSC sends via MAP signaling, the method further comprises: receiving local switching information of the second call subscriber, which the second MSC sends according to the address of the first MSC and transmits via MAP alarm system. 4. The method according to claim 3, in which the transmission of information switching to local reception through the MAP signaling contains:
the extension of the SEND ROUTING INFORMATION (SRI) request and the SECURE ROAMING NUMBER (PRN) request that belong to the current MAP signaling or the addition of MAP signaling to transmit switching information to local reception. 5. The method according to claim 2, in which before the first MSC center receives information on switching to local reception of the second call subscriber, which the second MSC center sends via the trunk signaling, the method comprises:
extension of the information request (INR) or information element (INF) that belongs to the SEND ROUTING INFORMATION (SRI) request and the SECURE ROAMING NUMBER (PRN) request, which belongs to the message of the independent transmission channel control protocol (BICC) message, or the extension of the INR element or INF, which belongs to the message of the subscriber signaling subsystem for a digital network with integrated service (ISUP), or adding MAP signaling to transmit the switching information to the local reception. 6. The method according to claim 1, wherein the first MSC processing center switching to local reception according to information switching to local reception of the first subscriber of the call and information switching to local reception of the second subscriber of the call contains:
when determining, by the first MSC center, according to the information of the BSC controller of the first call subscriber and the BSC of the second call subscriber, that both call subscribers belong to the same BSC controller, notification of the start of switching to local reception and notification of the mobile gateway station (MGW) about the release of interface resources A first caller of the call. 7. The method according to claim 6, in which the information of the BSC controller is the information of the signaling node of the BSC controller, the method also comprising:
determining, by the first MSC center, according to the information of the BSC signaling nodes of the controller of both the first call subscriber and the second call subscriber, whether both call subscribers belong to one BSC controller. 8. The method according to claim 1, in which the information switching to local reception of the first subscriber of the call or information switching to local reception of the second subscriber of the call contains any combination of the following types of information:
information about the possibility of switching to local reception of the corresponding subscriber of the call;
Call-ID identifier of the corresponding call subscriber; and channel information A of the interface of the respective call subscriber. 9. The method of claim 8, wherein when switching information to a local reception of a first call subscriber or switching information to a local reception of a second call subscriber comprises information about switching to a local reception of a corresponding call subscriber, performing, by a first MSC center, processing switching to a local receiving according to the local switch information of the first call subscriber or the local switch information of the second call subscriber, the method also comprising:
when determining, according to the information of the BSC signaling node of the controller of the first call subscriber and the information of the BSC signaling node of the controller of the second MSC center, that both call subscribers belong to one BSC controller, and determining, by the first MSC center, according to the information of the possibility of switching to the local reception of the first call subscriber and information the possibility of switching to local reception of the second subscriber of the call, notifying the BSC of the controller about the start of switching to local reception and notifying the MGW of the gateway about the release of resources A interface sa second call subscriber. 10. The method according to claim 6 or 9, in which after notifying the MGW of the gateway about the release of resources A of the interface of the first subscriber of the call, the method further comprises:
sending an ADD_REPLY message of switching to local reception to the second MSC center so that the second MSC center notifies the MGW gateway about the release of resources A of the interface of the first subscriber of the call, according to the message ADD_REPLY of switching to local reception. 11. The method according to claim 6 or 9, in which, after setting the switch to local reception, the method further comprises:
a request for access of the first MSC center to the resources A of the interface of the first call subscriber from the MGW of the gateway according to the local switch information of the first call subscriber and the local switch information of the second call subscriber;
if the access of the first subscriber of the call to the resources of the interface A is successfully received, then the request for disconnecting the switch to local reception is sent to the second MSC center, so that the second MSC center gets access to the resources A of the interface of the second subscriber from the MGW gateway according to the request to disconnect the switch to local reception; and
after receiving a confirmation (ACK), which returns from the second MSC of the center and indicates that access to the resources of the interface A of the second subscriber of the call has been received successfully, the BSC notifies the controller of the disconnection of switching to local reception. 12. The method according to claim 6, which further comprises:
receiving by the second MSC center the local switch information of the first call subscriber sent by the first MSC center; and
when the second MSC determines, according to the information of the BSC signaling node of the controller of the second call subscriber and the BSC information of the controller of the first call subscriber, that both call subscribers belong to the same BSC controller, the BSC controller is notified of the start of switching to local reception and the MGW is notified of the resource release gateway A second caller interface call. 13. The method according to item 12, in which after installing the switch to the local reception, the method further comprises:
the request of the second MSC of the resource access center A of the second call subscriber interface from the MGW of the gateway according to the local switch information of the second call subscriber and the local switch information of the first call subscriber;
if the request for access to the resources of the interface of the second call subscriber is successful, then sending the request to disconnect the switch to local reception to the first MSC center, so that the first MSC center accesses the resources A of the interface of the first subscriber from the MGW gateway according to the request to disconnect the switch to local reception; and
after receiving a confirmation (ASK), which returns from the first MSC of the center and indicates that access to the resources of the interface A of the first subscriber of the call has been received successfully, notification of the BSC of the controller about the disconnection of switching to local reception. 14. The method according to claim 6, 9 or 12, in which, when there is an interoffice transfer of control, the method further comprises:
if the first MSC center or the second MSC center determines, according to the information of the possibility of switching to local reception of both the first subscriber of the call and the second subscriber of the call, that both subscribers of the call have the ability to start switching to local reception, transmitting an indication indicating that the switch to local reception has begun, in the control transfer request sent to the final MSC center, so that, after completion of the control transfer, the final MSC center notifies the MGW gateway about the release of resources A of the local call subscriber interface and omlyaet BSC controller to start switching to the local reception according to the indication showing that switching to the local reception started successfully; and
receiving a control transfer response that returns from the end MSC center and indicates that the switch to local reception has started successfully. 15. A mobile switching center (MSC), comprising:
a receiving unit configured to receive local switch information of the second call subscriber sent by the second MSC center when both call subscribers are in the area of the first MSC center and the second MSC center, respectively; and
a processing unit configured to perform local switch switching processing according to local switch information of the first call subscriber and local switch information of the second call subscriber, wherein local switch information of the first call subscriber or local switch information of the second call subscriber contains information a base station controller (BSC) in the area of which the first call subscriber or second call subscriber is located. 16. The MSC center of claim 15, wherein the processing unit comprises:
a first evaluation subunit configured to evaluate whether both call subscribers belong to one BSC controller according to BSC information of the first call subscriber controller and BSC information of the second call subscriber controller received by the receiving unit; and
a notification subunit configured to notify the BSC of the controller of the start of switching to local reception and to notify the mobile gateway station (MGW) of the release of resources A of the local call subscriber interface when the first evaluation subunit determines that both call subscribers belong to the same BSC controller. 17. The MSC center of claim 16, wherein the receiving unit is further configured to receive local switch reception information of the second call subscriber when the local switch information of the first call subscriber or local switch information of the second call subscriber contains switchable information to local reception of the first call subscriber or the second call subscriber; and
the processing unit further comprises:
a second evaluation subunit configured to perform an assessment of whether both call subscribers have the ability to start switching to local reception, according to information of the possibility of switching to local reception of the first call subscriber and information of the possibility of switching to local reception of the second call subscriber received by the receiving unit; and
a notification subunit further configured to notify the BSC of the controller of the start of switching to local reception and to notify the mobile gateway station (MGW) of the release of resources A of the local call subscriber interface when the second evaluation subunit determines that both call subscribers are able to switch to local reception. 18. The MSC center of claim 16, wherein the processing unit further comprises:
the first sending subunit configured to send the local switch reception message ADD_REPLY to the second MSC center so that the second MSC center notifies the MGW gateway about the release of resources A of the interface of the second call subscriber, according to the local switch message ADD_REPLY. 19. The MSC center of claim 17, wherein the processing unit further comprises:
an access obtaining subunit configured to access resources A of a local call subscriber interface from the MGW gateway according to local switch information of the first call subscriber and local switch information of the second call subscriber;
the first sending subunit, additionally configured to send the local disconnect switch disconnect request to the second MSC center, after the subunit successfully receives the local subscriber interface access resources A so that the second MSC center accesses the second subscriber interface resources A from the MGW gateway , according to the request for disconnecting the switch to local reception; and
a notification subunit, additionally configured to notify the BSC of the controller of the disconnection of switching to local reception, after receiving an acknowledgment (ASK), which returns from the second MSC center and indicates that access to the resources of the interface A of the second call subscriber has been obtained. 20. The MSC center of claim 19, wherein the processing unit further comprises:
a control transfer processing subunit configured to, when the second evaluation subunit determines that both call subscribers are able to start switching to local reception, transmit an indication indicating that the switching to local reception has begun, in a control transfer request sent to the final MSC center, so that after completion of the control transfer, the final MSC center notifies the MGW gateway about the release of resources A of the local call subscriber interface, notifies the BSC controller about the start of switching to the local Receiving according display, indicating that switching of the local reception started successfully, and then receives the transmission control response that is returned from the end MSS center and shows that switching to the local reception started successfully. 21. A communication system comprising a first mobile switching center (MSC) and a second MSC center, in which:
the first MSC center is configured so that when both call subscribers are in the area of the first MSC center and the second MSC center, respectively, to receive switching information for local reception of the second call subscriber sent by the second MSC center, and to perform switching processing to local reception according to the switching information on local reception of the first subscriber of the call and information switching to local reception of the second subscriber of the call, and information switching to local reception of the first subscriber of the call or information switching to the reception of the second call subscriber contains information of the base station controller (BSC) in the area of which the first call subscriber or the second call subscriber is located; and
the second MSC center is configured to send switching information for local reception of the second call subscriber to the first MSC center. 22. The communication system according to item 21, in which:
the second MSC center is configured to send the switching information for local reception of the second call subscriber to the first MSC center through the signaling of the mobile application subsystem (MAP) or trunk signaling.

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