WO2012079449A1

WO2012079449A1 - Method and system for implementing bi-directional voice intercom

Info

Publication number: WO2012079449A1
Application number: PCT/CN2011/082852
Authority: WO
Inventors: 霍东风; 付永刚; 钟泽明
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-12-15
Filing date: 2011-11-24
Publication date: 2012-06-21
Also published as: CN102035840A

Abstract

Disclosed are a method and system for implementing bi-directional voice intercom, which is applied to a video surveillance system. The method comprises: a first IP multimedia subsystem (IMS) core network device receiving a call request initiated by a surveillance client, wherein the first IMS core network device is located in a domain where a surveillance front end to be accessed by the surveillance client is; the first IMS core network device sending the call request to the surveillance front end; and the first IMS core network device receiving a call success response message returned by the surveillance front end, and forwarding the message to the surveillance client. According to the technical solution provided by the present invention, intercommunication among surveillance front ends or surveillance platforms of different manufacturers may be achieved, thereby effectively improving the user experience.

Description

The present invention relates to the field of communications, and in particular to a method and system for implementing two-way voice intercom. BACKGROUND In the related art, in a video monitoring system, when a monitoring center needs to perform a voice conversation with a monitoring point, for example, when an alarm occurs at a monitoring point or a monitoring center directs a monitoring point to handle an alarm, the monitoring center and the monitoring point generally pass The private protocol establishes a voice conversation link, and the monitoring point and the monitoring center transmit voice data on the link, and each telecommunication operator requires the monitoring point and the monitoring center to open to the outside, allowing monitoring terminals or monitoring of different manufacturers. The platforms are all interoperable. Under the above circumstances, if a proprietary protocol is also adopted, voice dialogue with other manufacturers' video surveillance systems cannot be performed, and the open standards required by the telecom operators cannot be met. SUMMARY OF THE INVENTION The present invention provides a method and system for implementing two-way voice intercom to solve at least the above problems, in view of the problem that a private protocol is used in the related art and cannot perform voice conversation with a video surveillance system of other manufacturers. According to one aspect of the invention, a method of implementing a two-way voice intercom is provided. The method for implementing the two-way voice intercom according to the present invention includes: the first IP multimedia subsystem IMS core network device receives a call request initiated by the monitoring client, where the first IMS core network device is located at the monitoring client and needs to be accessed. Monitoring the domain where the front end is located; the first IMS core network device sends a call request to the monitoring front end; the first IMS core network device receives the call success response message returned from the monitoring front end, and forwards the message to the monitoring client. In the above method, when the first IMS core network device forwards the success response message returned by the monitoring front end to the monitoring client, the method further includes: sending, by the second IMS core network device in the domain where the monitoring client is located, the first notification to the application server AS The message, where the first notification message is used to indicate that the monitoring client and the monitoring front end are ready to perform two-way voice intercom; the AS forwards the voice data between the monitoring client and the monitoring front end. In the above method, before the IMS core network device receives the call request initiated by the monitoring client, the method further includes: the first IMS core network device receiving the first registration request from the monitoring front end, where the first note is The first IMS core network device sends a registration request to the monitoring front end, and the first IMS core network device sends a registration request to the AS, where the first IMS core network device sends a registration request to the AS. The registration request is used to request registration of the monitoring front end to the AS; when the registration is successful, the first IMS core network device receives a successful response from the AS return. In the above method, before the IMS core network device receives the call request initiated by the monitoring client, the method further includes: the second IMS core network device receiving the first registration request from the monitoring client, where the first registration request carries Authenticating information; the second IMS core network device performs authentication authentication on the monitoring client, and returns a successful response to the monitoring client when the authentication authentication succeeds; the second IMS core network device sends a registration request to the AS, where The registration request is for requesting registration of the monitoring client to the AS; when the registration is successful, the second IMS core network device receives a successful response from the AS return. In the above method, the first IMS core network device receives the call request initiated by the monitoring client, including: the monitoring client determines the monitoring front end that needs to be accessed; the monitoring client sends a call request to the second IMS core network device, where The call request carries the identifier of the monitoring front end; the second IMS core network device determines, according to the identifier of the monitoring front end, whether the monitoring front end is located in the domain of the first IMS core network device; if yes, directly initiates a call request to the monitoring front end; And sending a call request to the first IMS core network device. In the above method, after the first IMS core network device forwards the success response message returned by the monitoring front end to the monitoring client, the method further includes: the first IMS core network device receiving the hang up request initiated by the monitoring client or the monitoring front end When the monitoring client initiates the hangup request, the first IMS core network device sends the hangup request to the monitoring front end, receives the hangup response message returned from the monitoring front end, and forwards the message to the monitoring client; When the request is broken, the first IMS core network device sends a hangup request to the monitoring client, receives the hangup response message returned from the monitoring client, and forwards the message to the monitoring front end. In the above method, when the first IMS core network device forwards the hangup response message returned by the monitoring front end to the monitoring client, or forwards the hangup response message returned by the monitoring client to the monitoring front end, the method further includes: The core network device sends a second notification message to the application server AS, where the second notification message is used to indicate that the session between the monitoring client and the monitoring front end has been hung up. According to another aspect of the present invention, an implementation system for two-way voice intercom is provided. The system for implementing the two-way voice intercom according to the present invention includes: a monitoring client, configured to send a call request; and a first IMS core network device, located in a domain of the monitoring front end that the monitoring client needs to access, and configured to be from the monitoring The client's call request is forwarded to the monitoring front end, and the call success response message from the monitoring front end is forwarded to the monitoring client; the monitoring front end is set to send a call success response message. In the above system, the method further includes: a second IMS core network device, located in a domain of the monitoring client, configured to send a first notification message to the application server AS, where the first notification message is used to indicate the monitoring client and the monitoring front end Prepare for two-way voice intercom; AS, set to forward voice data between the monitoring client and the monitoring front end. In the above system, the first IMS core network device and the second IMS core network device are the same IMS core network device. In the above system, the monitoring front end is further configured to be registered to the first IMS core network device; and the monitoring client is further configured to be registered to the second IMS core network device. In the above system, the monitoring client or the monitoring front end is further configured to actively initiate the hang up request; the first IMS core network device is further configured to send the hang up request from the monitoring client to the monitoring front end, and receive the monitoring front end from the monitoring front end. The returned hangup response message is forwarded to the monitoring client; or the hangup request from the monitoring front end is sent to the monitoring client, and the hangup response message returned from the monitoring client is received and forwarded to the monitoring front end. Through the invention, in the video monitoring system, based on the IMS core network device, the monitoring client and the monitoring front end use a standard protocol for voice intercom, and realize the two-way voice intercom function between the monitoring client and the monitoring front end, and solve the related The technology adopts a proprietary protocol, and cannot communicate with other manufacturers' video surveillance systems, thereby enabling interoperability between monitoring front ends or monitoring platforms of different manufacturers, thereby effectively improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a system for implementing a two-way voice intercom according to an embodiment of the present invention; FIG. 2 is a schematic diagram of a two-way voice intercom system according to a preferred embodiment of the present invention; FIG. 4 is a flowchart of a monitoring front end registration according to an embodiment of the present invention; FIG. 5 is a two-way voice intercom method without cross-domain according to a preferred embodiment of the present invention; flow chart; 6 is a flow chart of a two-way voice intercom method in cross-domain according to a preferred embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. The technical features and advantages of IMS unified access control, convergence of various multimedia services, and multimedia service quality reliability are being recognized by telecom operators. Telecom operators are stepping up deployment of IMS core networks and gradually migrating various services to IMS cores. Online. Unified access, unified call, and media session establishment in IMS can easily implement service integration between various applications. The video surveillance service is essentially a multimedia service. The video surveillance service based on the IMS architecture is the development trend of the video surveillance service technology. The present invention provides a system for implementing two-way voice intercom based on an IMS core network device, which will be described below in conjunction with FIG. 1. 1 is a structural block diagram of a two-way voice intercom implementation system according to an embodiment of the present invention. As shown in FIG. 1 , the two-way voice intercom system includes: a monitoring client 10 configured to send a call request; and a first IMS core network device 12 located in a domain of a monitoring front end that the monitoring client needs to access, and is configured to be The call request from the monitoring client is forwarded to the monitoring front end, and the call success response message from the monitoring front end is forwarded to the monitoring client; the monitoring front end 14 is set to send a call success response message. In the above two-way voice intercom implementation system, based on the IMS core network device, the monitoring client and the monitoring front end use a standard protocol for voice intercom, and the monitoring systems of different manufacturers can intercommunicate, which is very convenient for the telecom operator to propose. The open requirements are convenient for users and provide a good method for operators. The monitoring client 10 and the monitoring front end 14 need to be registered to the IMS core network device before establishing the two-way voice intercom. This registration process will be described in detail later. Preferably, as shown in FIG. 2, the implementation system of the two-way voice intercom may further include: a second IMS core network device 16, located in a domain of the monitoring client, configured to send a first notification message to an application server (AS), The first notification message is used to indicate that the monitoring client and the monitoring front end are ready to perform two-way voice intercom; and the AS 18, the internal media server MS 180 can forward the voice data between the monitoring client and the monitoring front end. It should be noted that when the monitoring client 10 and the monitoring front end 14 are located in the same domain, the first IMS core network device and the second IMS core network device are the same IMS core network device. When the monitoring client 10 and the monitoring front end 14 are located in different domains, the first IMS core network device and the second IMS core network device are different IMS core network devices. Preferably, the monitoring client 10 or the monitoring front end 14 can initiate a hangup request actively; the first IMS core network device 12 is further configured to send a hangup request from the monitoring client 10 to the monitoring front end 14, and receive the The hangup response message returned by the monitoring front end 14 is forwarded to the monitoring client 10; or the hangup request from the monitoring front end 14 is sent to the monitoring client 10, and the hangup response message returned from the monitoring client 10 is received. And forwarded to the monitoring front end 14. In the preferred implementation process, the above monitoring front end is connected to a camera (either a built-in camera or an external camera) and a voice input device (which may be an external microphone or a built-in microphone), video data input to the camera and audio data input by the microphone. Encode and send the media stream. The video encoding method supported by the monitoring front end can be H.264 or a more commonly used encoding method such as MPEG4. The audio coding method can be G.711 or a commonly used coding method such as AAC. The remaining monitoring front ends can be connected to multiple cameras or multiple microphones, placed in different locations, and can be monitored by multiple monitoring points. The monitoring front end is used as a user equipment (UE) to access the IMS core network in a unified manner, and the IMS performs unified security access authentication. In the specific implementation process, the interface protocol between the monitoring client and the IMS Core (IMS Core) device may adopt a SIP/SDP protocol or the like. The IMS core network (IMS Core) device can implement routing and transmission of signaling messages, implement unified access and management of the terminal, and set different service signaling rules to trigger corresponding signaling to the corresponding application server. deal with. The above monitoring client (CU) receives the media stream through the network, decodes and displays the video image or sound. The monitoring client is also connected to the IMS core network as a user equipment (UE). The IMS performs security access authentication and is generally deployed in the monitoring center. The interface protocol between the monitoring client and the IMS Core can adopt the SIP/SDP protocol. The above application server (AS): can exist as a specific application server, and is responsible for processing all services related to video surveillance. Specifically, the AS includes but is not limited to the following functional entities: service discovery function (SDF), service selection function (SSF), Service Control Function (SCF), Media Server (MS). The Video Surveillance Application Server (AS) is responsible for processing various services and media services related to video surveillance. It is connected to the IMS Core Network (IMS Core), and the interface protocol can use the SIP/SDP protocol. FIG. 3 is a flowchart of a two-way voice intercom method according to an embodiment of the present invention. The method is applied to a video surveillance system. As shown in FIG. 3, the two-way voice intercom method mainly includes the following processing: Step S302: First The IMS core network device receives the call request initiated by the monitoring client, where the IMS core network device is located in the domain of the monitoring front end that the monitoring client needs to access; Step S304: The first IMS core network device sends a call request to the monitoring front end. Step S306: The first IMS core network device receives the call success response message returned from the monitoring front end, and forwards the message to the monitoring client. In the above method, the IMS core network device implements a two-way voice intercom function between the monitoring client and the monitoring front end, and the client and the monitoring front end use a standard protocol for voice intercom, and the monitoring systems of different manufacturers can communicate with each other. It is very convenient to meet the open requirements put forward by telecom operators, which is convenient for users and provides a good method for operators. Preferably, before the step S302 is performed, the monitoring client needs to be registered to the second IMS core network device in the domain where the monitoring client is located, and the monitoring front end needs to be registered to the first IMS core network device in the domain where the monitoring front end is located. . The following describes the process of monitoring the client and the monitoring front end to register with the IMS core network device. The monitoring front end registration to the first IMS core network device mainly includes the following processing:

(1) The first IMS core network device receives the first registration request from the monitoring front end, where the first registration request carries the authentication information;

(2) The first IMS core network device performs authentication and authentication on the monitoring front end, and returns a successful response to the monitoring front end when the authentication and authentication succeeds;

(3) The first IMS core network device sends a registration request to the AS, where the registration request is used to request to register the monitoring front end to the AS;

(4) Upon successful registration, the first IMS core network device receives a successful response from the AS return. The registration of the monitoring client to the second IMS core network device mainly includes the following processing: (1) The second IMS core network device receives the first registration request from the monitoring client, where the first registration request carries the authentication information; (2) The second IMS core network device performs authentication and authentication on the monitoring client, and returns a successful response to the monitoring client when the authentication and authentication succeeds;

(3) The second IMS core network device sends a registration request to the AS, where the registration request is used to request to register the monitoring client to the AS; (4) when the registration is successful, the second IMS core network device receives the return from the AS. Successful response. In the preferred implementation process, the video surveillance front end (PU) and the video surveillance client (CU) register with the IMS core network by using their saved user name, password, etc., and after successful registration, the IMS core network is directed to the video surveillance application server ( The AS) submits the registration request of the PU and the CU, and the AS also saves the registration status of the PU and the CU for various video surveillance applications, such as browsing real-time video. The following describes the monitoring front end registration process shown in Figure 4 as an example. Step S402: The monitoring front end initiates a registration request to the IMS core network, and carries incomplete authentication information, such as Authorization: Digest username="PUID@zte.com.cn"; The network returns a 401 authentication challenge response to the PU. Step S406: After receiving the 401 response, the PU re-initiates a Register request to the IMS core network. This request message carries complete authentication information, such as Authorization: Digest username=" PUID@zte.com.cn ": realm="zte. com.cn", nonce="57cc4d087e7537859fab6d2ec86b2fe7", uri="sip:zte Com.cn", response="08209aec3d8292d03234c365497becad",cnonce="401828850",

Algorithm=MD5,opaque="" ; where the response table cannot be response= MD 5 (MD 5 (username: realm: pas sword): nonce : nc : cnonce : qop : MD 5 (REGI S TER: uri)) Step S408, the IMS core network performs authentication and authentication, and after successful, returns 200 OK to the PU, and the PU registers to

The IMS system succeeds; Step S410: The IMS core network initiates a Register request to the AS according to the service triggering rule, and requests the PU to also register with the AS. Step S412, the AS returns a 200 OK response to the IMS system, and the PU registration process ends. Preferably, the above step S102 may further include the following processing:

(1) The monitoring client determines the monitoring front end that needs to be accessed; (2) The monitoring client sends a call request to the second IMS core network device, where the call request carries the identifier of the monitoring front end;

(3) The second IMS core network device determines, according to the identifier of the monitoring front end, whether the monitoring front end is located in the domain of the first IMS core network device; (4) if yes, directly initiates a call request to the monitoring front end;

(5) Otherwise, a call request is sent to the first IMS core network device. In a preferred implementation process, the monitoring client can select a monitoring front end to start dialing a two-way voice intercom, and the monitoring client carries the front end number to be talked to initiate a call to the second IMS core network device in the access domain. The second IMS core network device receives the request, and determines whether the number is in the domain, for example, in the domain, directly initiates a call to the front-end number. If not in the domain, the IMS core network sends another IMS core network device in the domain where the monitoring front-end is located. (ie the first IMS core network device) initiates a call. After receiving the call request, if the monitoring front end does not cross the domain, the IMS core network device responds to the monitoring client, such as the inter-domain, and the first IMS core network of the monitoring front-end domain first responds to the client's domain. The second IMS core network device, the second IMS core network device responds to the monitoring client, and the session is successfully established, and a voice call can be performed between the monitoring client and the monitoring front end. Preferably, when performing step S106, the following processing may also be included:

(1) The second IMS core network device in the domain where the monitoring client is located sends a first notification message to the application server AS, where the first notification message is used to indicate that the monitoring client and the monitoring front end are ready to perform two-way voice intercom;

(2) The AS forwards voice data between the monitoring client and the monitoring front end. Preferably, after performing step S306, the following processing may be further included: (1) the first IMS core network device receives the hang up request initiated by the monitoring client or the monitoring front end;

(2) When the monitoring client initiates the hangup request, the first IMS core network device sends the hangup request to the monitoring front end, receives the hangup response message returned from the monitoring front end, and forwards the message to the monitoring client;

(3) When the monitoring front end initiates the hang up request, the first IMS core network device sends the hang up request to the monitoring client, receives the hang up response message returned from the monitoring client, and forwards the message to the monitoring front end. When the first IMS core network device forwards the hangup response message returned by the monitoring front end to the monitoring client, or forwards the hangup response message returned by the monitoring client to the monitoring front end, the following processing may also be included: IMS core network device (that is, monitoring the IMS core network device in the domain where the client is located) to the application server The AS sends a second notification message, where the second notification message is used to indicate that the session between the monitoring client and the monitoring front end has been hung up. In the preferred implementation process, both the monitoring client and the monitoring front end can actively end the call. For example, the monitoring client needs to actively end the call, and the monitoring client can initiate a hangup request to the second IMS core network device. The IMS core network device directly forwards the hangup request to the monitoring front end. If the IMS core network device crosses the domain, the second IMS core network initiates a call request to another IMS core network device (ie, the first IMS core network device) in the domain where the monitoring front end is located, and then forwards the request. Go to the monitoring front end. After receiving the hangup request, the monitoring front end returns a hangup request response, and then forwards the message to the monitoring client through the IMS core network device, and notifies the AS that the session between the monitoring client and the monitoring front end is hanged. The call process ends. Figure 5 and Figure 6 show the flow of two-way voice intercom of the monitoring system without cross-domain and cross-domain. Below is shown in Figure 5 and

6 is a detailed description of the flow of the two-way voice intercom of the monitoring system. The description here uses the current common SIP protocol as an example. FIG. 5 is a flowchart of a two-way voice intercom method in cross-domain according to an embodiment of the present invention. As shown in FIG. 5, the two-way voice intercom method includes the following steps: Step S502: A customer (Customer Unit, CU for short) selects a monitoring front end (Pre-Unit, referred to as PU) to start a two-way voice pair with the PU. The INVITE request is initiated to the IMS core network (IMSCore) device in the domain where the CU is located, where the INVITE request carries the SDP information of the CU itself, for example, an audio encoding format, a code rate, a receiving IP address, and a port. Wait. Step S504: The IMSCore device detects that the selected PU is in the domain, and forwards the INVITE request to the PU. Step S506: After receiving the request, the PU parses the request and responds to the 200 OK message, where the message carries the SDP information of the PU, for example, an audio encoding format, a code rate, a receiving IP address, a port, and the like. Step S508, the IMSCore device forwards the 200 OK response message to the CU. Step S510: The CU receives the 200 OK message, parses the SDP information of the PU, and responds to the ACK message to the IMSCore device. Step S512, the IMSCore device forwards the ACK message to the PU. Step S514: The IMSCore device notifies the AS by using the MESSAGE message, and the CU has established a session with the PU, where the MESSAGE message carries the address and port information of the data of the CU and the PU. Step S516, the AS returns a 200 OK message to the IMSOCore device, and the internal MS starts to forward the voice data of the CU and the PU, and the CU and the PU can perform the voice intercom normally. Step S518: When the hangup is required, both the CU and the PU can hang up the session actively. Here, the CU actively hangs up the description, and the CU actively initiates a BYE request to the IMSCore device. Step S520: The IMSCore device forwards the BYE request to the PU. Step S522, the PU responds to the 200 OK message to the IMSCore device. Step S524, the IMSCore device forwards the 200 OK message to the CU. Step S526, the IMSCore device sends a MESSAGE message to the AS, and notifies that the session between the CU and the PU has been hung up. Step S528, the AS responds to the 200 OK message to the IMSCore device, and the call ends. 6 is a flow chart of a two-way voice intercom method in cross-domain according to an embodiment of the present invention. As shown in FIG. 6, the two-way voice intercom method includes the following steps: Step S602: The CU selects a PU, starts a two-way voice intercom with the PU, and initiates an INVITE request to the IMSCore (1) device in the domain where the CU is located, where The request carries the SDP information of the CU itself, for example, an audio encoding format, a code rate, a receiving IP address, and a port. Step S604: The IMSCore (1) device detects that the selected PU is not in the domain, and forwards the INVITE request to the IMSCore(2) device in the domain where the PU is located. Step S606: The IMSCore (2) device forwards the INVITE request to the PU. Step S608: After receiving the request, the PU parses the request and responds to the 200 OK message, where the message carries the SDP information of the PU, for example, an audio encoding format, a code rate, a receiving IP address, a port, and the like. Step S610, the IMSCore (2) device forwards the 200 OK response message to the IMSCore(1) device. Step S612, the IMSCore (1) device forwards the 200 OK response message to the CU. Step S614, the CU receives the 200 OK message, parses the SDP information of the PU, and responds to the ACK message to the IMSCore (1) device. Step S616, the IMSCore (1) device forwards the ACK message to the IMSCore (2) device. Step S618, the IMSCore (2) device forwards the ACK message to the PU. Step S620: The IMSCore (1) device notifies the AS by using the MESSAGE message, and the CU has established a session with the PU, where the MESSAGE message carries the address and port information of the data of the CU and the PU. Step S622, the AS returns a 200 OK message to the IMSCore (1) device, and the internal MS starts to forward the voice data of the CU and the PU, and the CU and the PU can perform the voice intercom normally. Step S624: When the hangup is required, both the CU and the PU can hang up the session actively. Here, the CU actively hangs up the description, and the CU actively initiates a BYE request to the IMSCore (1) device. Step S626, the IMSCore (1) device forwards the BYE request to the IMSCore (2) device. Step S628, the IMSCore (2) device forwards the BYE request to the PU. Step S630, the PU responds to the 200 OK message to the IMSCore (2) device. Step S632, the IMSCore (2) device forwards the 200 OK message to the IMSCore (1) device. Step S634, the IMSCore (1) device forwards the 200 OK message to the CU. Step S636: The IMSCore (1) device sends a MESSAGE message to the AS, notifying that the session between the CU and the PU has been hung up. Step S638, the AS responds to the 200 OK message to the IMSCore (1) device, and the call ends. In summary, with the above embodiments provided by the present invention, two-way voice intercom can be conveniently implemented at any time. When an alarm or other situation occurs at the monitoring point, the monitoring center can conveniently contact the monitoring front end in time to coordinate the processing monitoring point. At the same time, the monitoring client and the monitoring front end use standard protocols for voice intercom. The monitoring systems of different manufacturers can communicate with each other, which is very convenient to meet the opening requirements put forward by the telecom operators, which is convenient for users and also The operator has provided convenience. Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein. Perform the steps shown or described, or separate them into individual integrated circuit modules, or Multiple of these modules or steps are fabricated as a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

1. A method for implementing a two-way voice intercom, applied to a video surveillance system, comprising:

The first IMS core network device receives the call request initiated by the monitoring client, where the first IMS core network device is located in the domain of the monitoring front end that the monitoring client needs to access;

The first IMS core network device sends the call request to the monitoring front end; the first IMS core network device receives a call success response message returned from the monitoring front end, and forwards the message to the monitoring client.

The method according to claim 1, wherein, when the first IMS core network device forwards the success response message returned by the monitoring front end to the monitoring client, the method further includes:

The second IMS core network device in the domain where the monitoring client is located sends a first notification message to the application server AS, where the first notification message is used to indicate that the monitoring client and the monitoring front end are ready to perform two-way voice intercom ;

The AS forwards voice data between the monitoring client and the monitoring front end.

The method according to claim 2, wherein before the IMS core network device receives the call request initiated by the monitoring client, the method further includes:

Receiving, by the first IMS core network device, a first registration request from the monitoring front end, where the first registration request carries authentication information;

The first IMS core network device performs authentication and authentication on the monitoring front end, and returns a successful response to the monitoring front end when the authentication authentication is successful;

The first IMS core network device sends a registration request to the AS, where the registration request is used to request to register the monitoring front end to the AS;

Upon successful registration, the first IMS core network device receives a successful response from the AS return.

The method of claim 2, wherein before the IMS core network device receives the call request initiated by the monitoring client, the method further includes: The second IMS core network device receives a first registration request from the monitoring client, where the first registration request carries authentication information;

The second IMS core network device performs authentication and authentication on the monitoring client, and returns a successful response to the monitoring client when the authentication and authentication succeeds;

The second IMS core network device sends a registration request to the AS, where the registration request is used to request to register the monitoring client to the AS;

When the registration is successful, the second IMS core network device receives a successful response from the AS return.

The method according to claim 1, wherein the receiving, by the first IMS core network device, a call request initiated by the monitoring client comprises:

The monitoring client determines the monitoring front end that needs to be accessed;

The monitoring client sends the call request to the second IMS core network device, where the call request carries an identifier of the monitoring front end;

The second IMS core network device determines, according to the identifier of the monitoring front end, whether the monitoring front end is located in a domain of the first IMS core network device;

If yes, the call request is directly sent to the monitoring front end;

If not, the call request is sent to the first IMS core network device.

The method according to any one of claims 1 to 5, wherein after the first IMS core network device forwards the success response message returned by the monitoring front end to the monitoring client, the method further includes: The first IMS core network device receives a hangup request initiated by the monitoring client or the monitoring front end;

When the monitoring client initiates the hangup request, the first IMS core network device sends the hangup request to the monitoring front end, receives a hangup response message returned from the monitoring front end, and forwards the message to the The monitoring client;

When the monitoring front end initiates the hang up request, the first IMS core network device sends the hang up request to the monitoring client, receives the hang up response message returned by the monitoring client, and forwards the message. To the monitoring front end.

The method according to claim 6, wherein the first IMS core network device forwards the hangup response message returned by the monitoring front end to the monitoring client, or returns the monitoring client When the hangup response message is forwarded to the monitoring front end, the method further includes:

The second IMS core network device sends a second notification message to the application server AS, where the second notification message is used to indicate that the session between the monitoring client and the monitoring front end has been hung up.

8. A two-way voice intercom implementation system for use in a video surveillance system, comprising:

Monitoring client, set to send a call request;

The first IMS core network device is located in a domain of the monitoring front end that the monitoring client needs to access, and is configured to forward the call request from the monitoring client to the monitoring front end, and The call success response message of the monitoring front end is forwarded to the monitoring client;

The monitoring front end is configured to send the call success response message.

9. The system according to claim 8, further comprising:

The second IMS core network device is located in the domain of the monitoring client, and is configured to send a first notification message to the application server AS, where the first notification message is used to indicate that the monitoring client and the monitoring front end are ready to perform Two-way voice intercom;

The AS is configured to forward voice data between the monitoring client and the monitoring front end.

10. The system according to claim 9, wherein the first IMS core network device and the second IMS core network device are the same IMS core network device.

The system according to any one of claims 8 to 10, comprising:

The monitoring front end is further configured to be registered to the first IMS core network device; the monitoring client is further configured to register with the second IMS core network device.

The system according to any one of claims 8 to 10, wherein

The monitoring client or the monitoring front end is further configured to initiate an hang up request; the first IMS core network device is further configured to send the hang up request from the monitoring client to the monitoring The front end receives the hangup response message returned from the monitoring front end and forwards the message to the monitoring client, or sends the hangup request from the monitoring front end to the monitoring client, and receives the hangup request from the monitoring front end. The hangup response message returned by the monitoring client is forwarded to the monitoring front end.