KR20040003939A - DVR system capacitated to transmit instant mesage using SIP and method thereof - Google Patents

Abstract

PURPOSE: A DVR(Digital Video Recorder) system for transferring a message in real-time using the SIP(Session Initiation Protocol) and a method thereof are provided to realize an emergency call, the both-way communication/multimedia emergency message between a moving PDA(Personal Digital Assistant) and a control center, and the remote control of the DVR by applying the SIP to the DVR system. CONSTITUTION: A DVR(20), the control server(30), and the PDA(40) are connected through the wire/wireless network(60) including an SIP server(70), and include SIP agent systems(25,32,42). The SIP agent system connects the DVR, the control server, and the PDA by the SIP, registers the current position information and the state information received from the SIP server, and transmits a text, a voice, or a video message in real-time. The DVR transmits an SIP message periodically or transmits an SIP message if a detection event occurs. The SIP server registers and manages the position information, the state information, and the user information of the DVR, the control server, and the PDA, processes a signal according to the message header information, transmits the message, and maps an SIP address.

Description

DVR system capable of real-time message delivery using SPI and its method {DVR system capacitated to transmit instant mesage using SIP and method

The present invention relates to a DVR system and a communication method thereof, and more particularly, to a DVR system and a method for real-time message transmission and remote control of a DVR using a Session Initiation Protocol (SIP).

DVR (Digital Video Recorder) is a device that converts video data input from surveillance camera into digital image on video capture board and stores it as a high-definition digital signal on storage media such as hard disk. It is a government office, financial institution, department store, large It is a security system that can be installed at discount stores, building management companies, apartments, hospitals, prisons, public restaurants, etc. to enable effective crime prevention and business management.

These DVRs have recently been diversified in their functions, so that multiplexers can divide and monitor multiple camera images on a single monitor, instant search of recorded data, real-time screen monitoring and sound through modem, LAN, and xDSL. It is possible to provide a sensing function and the like, and the use of the high-performance, low-cost products is generally expanding.

1 is a block diagram schematically illustrating a network connection configuration of a conventional DVR system.

According to FIG. 1, the existing DVR system is composed of one or more DVRs 10a, a control center 10b and a remote client such as a personal computer 10c, a telephone 10d and a mobile communication terminal 10e.

The DVR system is connected to the gatekeeper 14 and the gateway 15 via the Internet 11, and the gateway 15 connects the above-mentioned remote clients through the PSTN 12 and the mobile communication network 13. Among the remote clients, the personal computer 10c communicates with the DVR 10a or the control center 10b via the Internet (including the intra network) 11 and the Internet based on the HTTP (Hyper Text Transfer Protocol). Voice over Internet Protocol (VoIP) based voice data communication or email communication) is possible, and in the case of the telephone 10d, the gateway for interworking the gatekeeper 14 and the PSTN 12 which converts the manager's telephone number into an IP address Voice communication with the DVR 10a or the control center 10b is possible through the reference numeral 15.

According to the existing DVR technology, when the administrator leaves the place where the display device of the DVR 10a is installed or leaves the DVR control center 10b, the DVR 10a does not know the location of the manager. Not only does it send a warning signal to a pre-designated place, but it also sends mail to a pre-entered e-mail address as an alternative notification means if the administrator is located at a remote location instead of leaving for a while.

In addition, if the DVR 10a transmits an emergency message to the mobile communication terminal 10e using a short message service (SMS), the DVR 10a should be provided with a separate hardware device and the mobile communication terminal 10e. Intelligent message delivery or two-way real-time message transmission and reception by the status check of the) is not possible.

That is, the remote manager cannot flexibly check the emergency situation detected through the DVR 10a, the detection signal of the sensor and the failure signal of the device, and cannot receive a real time notification message from the DVR 10a. Remote control of the DVR 10a is possible only in the center 10b.

In the existing DVR system, the mobile communication terminal 10e such as PDA (Personal Digital Assistant) is connected to the control center 10b or the DVR 10a and the wireless Internet through the wireless internet gateway 15 and the wireless internet protocol server 16. Although communication is possible, the administrator using the mobile communication terminal 10e can only use the mail function on the wireless Internet and cannot use the emergency messaging function.

In addition, the existing DVR requires a separate Public Switched Telephone Network (PSTN) line and additional devices for remote emergency call or indoor monitoring, increasing installation costs and operating costs such as subscription and call charges.

Therefore, it provides various connection and connection efficiency between heterogeneous networks, and can make emergency call or indoor monitoring without additional installation cost, and intelligent push service is provided to provide the information that manager needs by understanding the location and status of manager. There is a need for development of more improved DVR systems.

The present invention has been made in order to meet the above requirements, applying the SIP protocol to the existing DVR system consisting of a DVR, a control server and a personal communication terminal and the SIP location registration server, SIP proxy server and SIP redirect server Enables data communication through wired / wireless networks, including emergency telephony via SIP function, SIP system for two-way / multimedia instant messaging and DVR remote control with mobile communication terminal and control center And its communication method.

1 is a block diagram schematically illustrating a network connection configuration of a conventional DVR system.

2 is a block diagram schematically illustrating a connection configuration through a wired / wireless network of a DVR system capable of real-time message delivery using SIP according to the present invention.

3A to 3B exemplarily illustrate data tables for user registration, data tables for user login, and data tables for client registration, respectively, managed by the SIP agent means.

4 is a block diagram schematically illustrating an internal configuration of a DVR according to an embodiment of the present invention.

5 is a data flow diagram illustrating a process of processing a message between a personal communication terminal and a DVR by a SIP redirection server according to the present invention.

6A to 6B are flowcharts illustrating a DVR system communication method capable of real-time message delivery using SIP according to the present invention.

7 is a diagram schematically illustrating the format of a SIP message transmitted by a SIP agent means to a SIP server according to the present invention.

<Explanation of symbols for main parts of drawing>

100: DVR system capable of real-time message delivery using SIP

20: DVR 25: SIP agent means of DVR

30: control server 32: SIP agent means of the control server

40: personal communication terminal 42: SIP agent means of the personal communication terminal

50: gateway 60: wired / wireless network

72: SIP location registration server 72a: location registration database

74: SIP proxy server 76: SIP redirect server

In order to achieve the above object, the DVR system capable of real-time message delivery using the SIP according to the present invention comprises a DVR, a control server, a personal communication terminal and a SIP server, one or more DVR, control server and personal communication The terminals are connected to each other through a wired / wireless network including a SIP server, and the DVR, control server and personal communication terminal are connected by the SIP protocol. And SIP agent means for transmitting and receiving voice or video messages in real time, respectively, and the DVR transmits a SIP message periodically or a SIP event when a detection event occurs according to a user's reservation setting. The server registers / manages location information, status information and user information of DVR, control server and personal communication terminal. , And processes the signal according to the message header information, to set up the call and transmits a message, it characterized in that it maps the SIP address.

In order to achieve the above another object, the DVR system communication method capable of real-time message delivery using SIP according to the present invention is (a) the SIP agent means of the DVR, personal communication terminal and control server mutual location information and state information Registering and waiting; (b) the DVR transmitting a SIP message to the control server and the personal communication terminal when a reservation setting time arrives or a detection event occurs; (c) the control server or the personal communication terminal receiving another SIP message corresponding to the received SIP message and transmitting it to the DVR; And (d) the DVR receives and analyzes the SIP message and remotely controls the control server or the personal communication terminal according to the analysis result.

Hereinafter, a DVR system capable of real-time message delivery using SIP according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram schematically illustrating a connection configuration through a wired / wireless network 60 of a DVR system 100 capable of real-time message transmission using SIP according to the present invention.

2, a DVR system (hereinafter, referred to as "the DVR system according to the present invention") 100 capable of real-time message transmission using SIP according to the present invention includes a DVR 20, a control server 30, It consists of a personal communication terminal 40 and a SIP server 70, the DVR 20, the control server 30 and the personal communication terminal 40 are each provided with SIP agent means (25, 32, 42) and SIP The server 70 is composed of a SIP location registration server 72, a SIP proxy server 74, a SIP redirect server 76 and a location registration database 72a. The gateway 50 performs a function of processing data communication between various wired / wireless networks 60.

SIP refers to a text-based application protocol that allows one or more clients to simultaneously form a session (teleconference, telephone, event notification, instant messaging, etc.). Based on the client / server architecture, SIP is independent of the underlying packet protocols (TCP, UDP, ATM, X.25), and adopts the format of existing text-based Internet standards, making it easy to troubleshoot and debug networks. Has

In order to process the SIP protocol, the DVR system 100 according to the present invention includes a SIP server 70. The SIP server 70 includes a SIP location registration server 72 and a SIP proxy server 74 as described above. And the SIP redirect server 76. Accordingly, the DVR system 100 according to the present invention can support all of H.323, MGCP (Media Gateway Control Protocol), NGN (Next Generation Network), Softswitch, RTP (Realtime Transfer Protocol).

As the personal communication terminal 40, a telephone, a SIP phone, a PDA, a desktop, a laptop, a mobile phone, etc. may be used. The wired / wireless network 60 may be an intra network (LAN), the Internet (IP network), a mobile communication network, or a public network. It is a broad concept, including a telephone network (PSTN) and a 3G mobile network.

The mobile communication network includes switching network parts such as mobile communication switch (PCX / VLR), signal network repeater (STP), subscriber information processing device (HLR), short message center (SMC), authentication center (AuC), and network interworking device (IWF). , A base station controller (BSC), a base station (BTS) such as a wireless network unit and a network management center (NMS / OMC), customer management / billing device (WISE) operation support unit, etc., mobile communication network interworking with the gateway 50 For other network configuration devices, such as PBX of PSTN on which a call agent is implemented, detailed description thereof will be omitted since it is well known to those skilled in the art.

The SIP agent means 25, 32, and 42 provided in the DVR 20, the control server 30, and the personal communication terminal 40 respectively connect the DVR 20, the control server 30, and the personal communication terminal 40. Each is connected by the SIP protocol, and the current location information and state information are received from the SIP server 70 and registered.

The SIP agent means 25, 32 and 42 transmit and receive text, voice or video messages in real time. The SIP agent means 25, 32 and 42 are similar to the existing messenger programs and are preferably implemented in software. In addition to the transmission function, it can provide chat function, file sharing function, audio / video conference function, and multi-transmission function. SIP agent means (25, 32, 42) can be linked to a variety of location registration / messenger private programs and existing messenger programs (for example, MSN messenger).

The SIP agent means (25, 32, 42) is provided with the location information and status information of each client from the SIP server 70, the SIP server 70 in the call setup and SIP message transmission, but basically the client-to-client It is based on the client's P2P file transfer technology.

In addition, the SIP agent means 25, 32, 42 provide a login function, a user registration function, a client (communication target) registration function, and the like.

3A to 3B exemplarily illustrate data tables for user registration, data tables for user login, and data tables for client registration, respectively, managed by the SIP agent means.

4 is a block diagram schematically showing the internal configuration of the DVR 20 according to an embodiment of the present invention.

According to FIG. 4, the DVR 20 according to the present invention includes an analog signal input device 21, a digital conversion means 22, a signal processing means 23, a SIP agent means 25, a storage means 24, and audio. / Video output means 26, control means 28 and the network interface 27.

As the analog signal input device 21, an external sensor such as a temperature sensor or an infrared sensor, a camera, a microphone, or the like may be used, and these devices generate analog data through photographing, sound collection, or sensing of a surveillance area.

The digital conversion means 22 captures the analog data sensed by the analog signal input device 21 and converts the analog data into digital video data or digital audio data, or generates other digital data corresponding to the analog data. It is delivered to the means 25 so that the SIP agent means 25 transmits a predetermined message. For example, when an object is detected by the infrared sensor, the digital conversion means 22 transmits the digital data for transmitting the "intrusion alarm message" to the SIP agent means 25.

The signal processing means 23 processes the converted digital video / audio data such as signal enhancement and signal compression, for example, to enhance an image through histogram processing, spatial filter processing, frequency filter processing, and color image processing. Compress images to save storage space.

The storage means 24 stores the digital data signal processed or generated, and controls data input and output with the digital conversion means 22, the signal processing means 23, and the SIP agent means 25.

The audio / video output device outputs digital data as analog video or analog sound.

The network interface 27 is connected to the wired / wireless network 60 to process the digital data communication so that the SIP agent means 25 can transmit and receive text data or digital data as multimedia data. When the control command message is received from the SIP agent means 25 of the control center and the personal communication terminal 40 through the network interface 27, the SIP agent means 25 converts it into a control signal and transmits it to the control means 28. do.

The control means 28 controls the analog signal input device 21, the signal processing means 23, the digital conversion means 22, the storage means, the audio / video output device and the network interface 27. The control means 28 may transmit the stored digital data to the control center via the network interface 27. The transfer function may use the file sharing function of the SIP agent means 25, but it is preferable to use the file transfer function through general networking.

The SIP agent means 25 of the DVR 20 periodically transmits a SIP message or detects an event by a user's reservation setting (the user can set a reservation through the control server 30 or the personal communication terminal 40). If occurs, it sends out SIP message. Here, the detection event is a case where the signal processing means 23 detects a specific image or a specific motion in the signal-processed digital image, or when the control means 28 detects a lack of storage space of the storage means 24, and the control means. Means when the 28 detects the abnormal operation of the analog signal input device (21).

The SIP agent means 25 of the DVR 20 checks the location and log state of the SIP agent means 42 of the personal communication terminal 40 in real time, and receives the preset settings from the personal communication terminal 40 or the control server 30. The SIP message can be transmitted by selecting the personal communication terminal 40 that can communicate through the profile. Therefore, even if the manager moving from a remote location is logged out, the DVR 20 can identify the location of the manager and check the available personal communication terminal 40 to transmit an emergency message. In addition, the SIP agent means 25 of the DVR 20 may be previously set the language to be used for the text message and the data type of the message (that is, video, voice, text, etc.) through the recording of the profile.

When the administrator checks the emergency message (multimedia data) through the SIP agent means 42 of the control center and the personal communication terminal 40 and transmits the DVR control command through the SIP agent means 42 in the form of a message, the DVR ( The SIP agent means 25 of the 20 analyzes this and causes the control means 28 to cause the analog signal input device 21, the signal processing means 23, the digital conversion means 22, the storage means 24, the audio / The video output device and the network interface 27 or the like are controlled or alarm broadcast is provided (the configuration device for alarm broadcast in FIG. 4 is omitted).

The SIP location registration server 72 tracks the location of the personal communication terminal 40 and registers / manages state information and location information of the control server 30 and the personal communication terminal 40 in the location registration database 72a. . The IP address of the personal communication terminal 40 is changed according to the situation (for example, PPP, DHCP, etc.). The SIP agent means 42 of the personal communication terminal 40 is connected to the SIP agent means 25 of the DVR 20. In order to connect, the SIP location registration server 72 provides a function of mapping an IP address and a SIP address.

The SIP location registration server 72 transmits a contact value "*" to cancel the current registration and transmit a new registration when the personal communication terminal 40 is moving or modifying a parameter for registration. .

The SIP proxy server 74 requests or responds to the processing of messages and call-related signals from the SIP agent means 25, 32, and 42 of the clients (DVR 20, personal communication terminal 40, control server 30). This intermediate server performs a real-time client / server function when the transmission is performed. Transcoding is performed and a message transmission area is managed.

In addition, the SIP proxy server 74 may set the request and response path of the message, and change the parameter values of the message header information before transmitting the request message and the response message to translate the ID. The SIP proxy server 74 preferably matches the transmission path of the request message and the response message.

The SIP redirect server 76 processes multiple transmissions of messages, translates IDs, and modifies the message transmission path according to the movement of the personal communication terminal 40 so that the DVR 20, the control server 30, or the personal communication terminal The call is distributed to 40 to distribute the call.

The SIP redirect server 76 sends a "3XX" response (or rejection response) to the INVITE request, for example "300" is the multi-transmission selection information, "301" is the set movement information (restricted movement information of the administrator). , "302" indicates any movement information not set, and "308" indicates a response to the service selection information.

5 is a data flow diagram illustrating a process of processing a message between the personal communication terminal 40 and the DVR 20 by the SIP redirect server 76 according to the present invention.

Hereinafter, a DVR system communication method capable of real-time message delivery using SIP according to the present invention will be described in detail with reference to the accompanying drawings. For convenience of explanation, it is assumed that the DVR 20 communicates with the manager's personal communication terminal 40 (that is, excludes the control server 30), and the personal communication terminal 40 is a PDA.

6A to 6B are flowcharts illustrating a DVR system communication method capable of real-time message delivery using SIP according to the present invention.

First, the SIP agent means 25 and 42 of the DVR 20 and the PDA 40 receive and register location information and status information from the SIP location registration server 72.

Subsequently, the DVR 20 transmits a SIP message to the PDA 40 when a reservation setting time arrives or a detection event occurs or a report command message is received from the PDA 40 (S100).

The communication process of SIP message is transaction based and there are steps that are partially overlapped in the whole process of communication. Thus, in order to avoid repetition of the description, the communication process of the SIP message will be described below using only the process of the DVR 20 transmitting the SIP message to the PDA 40 as an example.

If a predetermined message is transmitted from the DVR 20, the SIP server 70 analyzes what kind of message the received message is (S105). If the analyzed message is a response message (RQ_CS) for the successful call setup (S110), the SIP server 70 transmits a response message (ACK) to the gateway 50 and enters the reception standby state (S115). However, if the analyzed message is a call setup request message (RQ_ID) including hardware information and address information (S110), the SIP server 70 generates a session start request message (INVITE) according to the SIP protocol to the gateway 50. If a predetermined message is transmitted from the gateway 50 (S120) and the type of message is analyzed (S130).

At this time, the gateway 50 processes the call setup to the PDA 40 through the mobile communication network and receives a message from the PDA 40 and transmits the message to the SIP server 70.

If the message transmitted from the PDA 40 is a SIP protocol message (200 OK) that accepts a call setup request (S130), the SIP server 70 transmits a call setup success message (AC_CS) to the DVR 20 (S135). If the message is terminated or an error message (S130), the call setup failure message (AC_CF) is transmitted to the DVR 20 (S140). However, if the message received in step S110 is a message requesting release of call setup (RQ_BYE), SIP server 70 transmits a call setup end message (AQ_BYE) and sends a SIP protocol session end message (BYE) for call termination. It generates and transmits to the DVR 20 (S145).

Subsequently, the SIP server 70 transmitting the call setup success message to the DVR 20 notifies the SIP agent means 25 of the DVR 20 of the session start signal and the call setup progress state to complete the call setup (S150). ).

The SIP agent means 25 of the DVR 20 transmits a response message for the call setup to the SIP server 70 (S155), and sends the SIP to the SIP agent means 42 of the PDA 40 through an open communication channel. The message is transmitted (S160).

When the SIP agent means 25 of the DVR 20 terminates the transmission of the SIP message (S170), the call release request message is transmitted to the SIP server 70 (S145), and the SIP server 70 as described above. The SIP communication is terminated by receiving a response message from the call release.

FIG. 7 is a diagram schematically illustrating a format of a SIP message transmitted by a SIP agent means to a SIP server 70 according to the present invention.

According to Figure 7, SIP message is a start line (A), a general header (Cseq number, call number, from / to / via information, encryption information, etc.) (B) request header (C), entity (Entity) It consists of a header (D), a CRLF (a character representing a newline, which distinguishes the end of the header from the beginning of the data) (E), and a message body (F) including a Session Description Protocol (SDP).

The administrator who receives the message through the PDA 40 detects the situation of the monitoring area or the failure state of the DVR 20 and inputs a control SIP message to the PDA 40 to control the DVR 20 (S175). .

The SIP agent means 42 of the PDA 40 transmits a control SIP message to the DVR 20 by performing a call-related signal processing and message processing with the SIP server 70 as described above (S180). The SIP message transmission process from the PDA 40 to the DVR 20 is changed only in the object of transmission and reception, and thus the description thereof will be omitted.

Finally, the SIP agent means 25 of the DVR 20 receives and analyzes the SIP message (S185), and the control means 28 controls each component or provides an alarm broadcast according to the analysis result (S190). .

The present invention has been described above with reference to the preferred embodiments, which are merely examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not possible that are not illustrated above. For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

According to the present invention, an emergency message delivery service and an intelligent push service between clients connected to different types of networks are possible through a location registration function, and a failover, remote control (data storage, camera operation, data search and Data transmission, etc.), remote monitoring and remote alarm broadcasting. According to the present invention, two-way multimedia communication between a personal communication terminal, a control server, and a DVR can be implemented without installing an external device and a line, and interworking with NGN and Softswitch, which are next generation networking technologies, is possible.

In addition, according to the present invention, since a VoIP call can be configured through interworking with a SIP server and a gateway which are components of an existing SIP-based VoIP network, an emergency call can be made in other networks such as a PSTN or a mobile communication network without providing additional equipment. This makes it possible to economically provide indoor monitoring.

Claims (8)

In a DVR system having a DVR for monitoring a predetermined area, a server for controlling the DVR and a personal communication terminal receiving the monitoring information from the DVR through the Internet, One or more of the DVR, the control server and the personal communication terminal are interconnected via a wired / wireless network including a SIP server, and connects the DVR, the control server and the personal communication terminal by the SIP protocol, and the current location information of each other, It is provided with each SIP agent means for receiving and registering the status information received from the SIP server and can send and receive text, voice or video messages in real time, The DVR periodically transmits a SIP message or a SIP message when a detection event occurs according to a user's reservation setting. The SIP server registers / manages location information, status information, and user information of the DVR, control server, and personal communication terminal, processes signals according to message header information, sets a call, transmits a message, and sends a SIP address. DVR system capable of real-time message delivery using SIP characterized in that the mapping. The method of claim 1, wherein the DVR At least one analog signal input device for generating analog data through imaging of a surveillance area, sound collection, or external sensing; Data processing means for capturing the analog data, converting it into digital video data or digital audio data, signal processing, or generating other digital data corresponding to the analog data; Storage means for storing the signal processed or generated digital data; An audio / video output device for outputting the digital data as an analog image or an analog sound; A network interface connected to the wired / wireless network to process digital data communication so that the SIP agent means can transmit and receive text data or the digital data as multimedia data; And And an analog signal input device, a data processing means, a storage means, an audio / video output device and a control means for controlling a network interface. The method of claim 2, wherein the SIP agent means The data processing means detects a specific image or a specific motion in the signal-processed digital image, the DVR detects an abnormal indication through external sensing, or the control means lacks a storage space of the storage means and an analog signal input device. DVR system capable of real-time message delivery using a SIP, characterized in that for transmitting a SIP message when a detection event including a case of detecting an abnormal operation of the. The method of claim 1, wherein the SIP server A SIP location registration server that tracks the location of the personal communication terminal, registers / manages state information and location information of the control server and the personal communication terminal, and maps an IP address and a SIP address; And A DVR system capable of real-time message delivery using SIP, which performs transcoding, manages a message transmission area, sets a request and response path of a message, and translates an ID. The method of claim 1, wherein the SIP agent means of the DVR SIP, characterized in that for transmitting the SIP message by checking the location and log status of the SIP agent means of the personal communication terminal in real time, and selects a personal communication terminal that can communicate through a profile preset from the personal communication terminal or control server DVR system capable of real-time message delivery using. The method of claim 1, wherein the DVR Analyzing the SIP message transmitted from the personal communication terminal or the control server to control any one or more components of the analog signal input device, data processing means, storage means, audio / video output device and network interface or to provide an alarm broadcast DVR system capable of real-time message delivery using SIP. In the communication method of the DVR system, (a) the SIP agent means of the DVR, the personal communication terminal and the control server, registering and waiting for mutual location information and status information; (b) the DVR transmitting a SIP message to the control server and the personal communication terminal when a reservation setting time arrives or a detection event occurs; (c) the control server or the personal communication terminal receiving another SIP message corresponding to the received SIP message and transmitting the received SIP message to the DVR; And (d) The DVR system for receiving and analyzing the SIP message, the DVR system communication method capable of real-time message delivery using the SIP, characterized in that it comprises a remote control according to the analysis result. The method of claim 7, wherein step (b) or (c) The SIP agent means may include a first step of transmitting a call setup request message including hardware information and address information to a SIP server; Receiving, by the SIP server, the call establishment request message and notifying the SIP agent means of the session start signal and the call establishment progress status; The SIP agent means transmitting a response message to the call establishment to the SIP server, and transmitting the SIP message to the counterpart SIP agent means through an open communication channel; And The SIP agent means comprises a fourth step of terminating SIP communication by transmitting a call release request message to the SIP server and receiving a response message for the call release from the SIP server. DVR system communication method that can deliver messages.