【 Weak current College 】 softswitch technology and IP video conferencing application---Power By 【 China power house network 】

Video conferencing is through the Terminal and network, so that the participants can be in different places on the same topic to discuss, among not only can hear speakers sound and you can see the speaker's image and background, as well as exchange of information on the subject, data, text, charts, and other information, so participants can get richer than the phone conference information,


With VLSI circuits and computer technology, set computer interactivity, network distribution and synchronization of multimedia information for multimedia conferencing system broke through the computer, communications, television and other traditional boundaries, as it provides a new interactive services.
　　
Video conferences are in different locations of multiple real-time communication between users, including image information with participants of a high-quality voice, as well as other media information. When the Conference includes two or more Terminal, usually need a multipoint control unit (MCU). All terminals are received an MCU, MCU is responsible for each user to send a signal to select or make the appropriate mix of signalling and optional channel control and management. Video conferencing for typical applications include remote meetings between the various participants, the write file, display items (such as a new product), comments and contract negotiations (may require the parties to avoid private discussions or invited expert recommendations), distance education and training, telemedicine and remote auction, etc. Unlike traditional voice services in the single request, video conference communication system has set higher requirements, such as integration, interactivity, synchronization, and other characteristics. Soft switching device as the next generation of network voice services, data services and video services call, control, business provides one of the core equipment, was concerned about. Soft switch not only can inherit the traditional voice business, but well supported IP video conferencing.
　　
Softswitch requirement to call control features from media gateway (transport layer) separating the software connection control, translation and routing, gateway management, call control, bandwidth management, signalling, security, and generate call detail records, and other functions, to control and business ones. Soft switch provides packet switching network and circuit switching in the same function, so the softswitch also known as call forwarding or call Server.
　　
Softswitch is business related, it is based on the IP network to provide telecommunications services. In circuit-switched networks, the business provides call control, and switching matrix are concentrated in one system; while the softswitch main design idea is business, control, and transmit, access, all entities through a standard protocol for the connection and communication, more flexibility in providing business, namely the softswitch is based on software distributed exchange/control platform, it will call control features separate from gateway, so you can easily introduce a variety of business on the Internet.
　　
An introduction to IP video conferencing,
　　
1, the standard IP video conference
　　
In order to solve various vendor interoperability issues between products, and establish global unified videoconferencing standards, International Telecommunication Union (ITU) of the Telecommunication Standardization sector (ITU-T) since 1990, developing has issued a series of standards for video conferencing, forming a set of related video conference full standard system. Currently, video conference system can be based on two main frame ITU-T recommends H.323 and H.320.
　　
1990 launched H.320 standard is first generation videoconferencing standards, mainly applies to the narrowband ISDN (N-ISDN) network and dial-up VPN, concentrated on defining the ISDN video conferencing as well as the speed of 2Mbps 56kbps~ video conference, is now developing the most sophisticated technology and systems.
　　
1996 launch of H.323 defines a LAN, Intranet and Internet video conferencing framework proposal. It enables compliance with standards of different manufacturers with the system, you can communicate with each other on a LAN, a video conference development of new directions. H.323 defines LAN on video communications equipment, procedures and protocols. H.323 uses Internet Protocol compatible IETF RTP/RTCP standard, and plan to use a variety of packet switching network (PSN) protocols, including TCP/IP and Novell SPX/IPX protocol. H.323 protocol is a standard IP video conferencing.
　　
Initially, because the IP protocol is not very common, based on the ISDN line, in line with the agreement of products covers H.320 major proportions, with few years of the universal application of the IP Protocol and the rapid development of the Internet, especially for broadband network foreseen, in line with the H.323 protocol products since 2000, the overall proportion of markets has risen dramatically. With IP technology continues to improve and upgrade, international standards, IP video services and applications will gradually expand, application based on the H.323 platform will become increasingly widespread.
　　
H.323 standard covers the packet switching network, audio, video and data communications, resolve the point-to-point and multipoint video conferences such as the call session control, multimedia and bandwidth control. T.120 protocol H.323 reference to process data exchange.
　　
In H.323 recommendations, the image decoding format with H.263, H.261, H263 +. H.263 and H.263 + to images provide greater compression rate, to be able to provide low bit rate than H.261 better image quality, and therefore more suitable for the IP network applications.
　　
Audio coding format must be compatible with the G.711 voice coding, you can also choose to use the G.723.1, G.722,G.728, G.729 or MPEG-1 speech coding standard.

IP network video conferencing system uses packet switching technology for packet switching does not guarantee order and fixed time delay, and therefore are not guaranteed a fixed delay and bandwidth. In order to better address the real-time communication service quality, the use of UDP/IP, RTP, RTCP, RSVP, and other protocols.
　　
H.323 has the following main advantages. H.323 protocol is designed to run on the common network architecture, network-independent. H.323 protocol provides network bandwidth management function, to be able to network with h.323 connections and H.323 applications available to limit the total amount of bandwidth. H.323 provides connections are based on circuit-switched or ISDN video conferencing tool. H.323 support multipoint and multipoint Conference broadcast (multicast). H.323 implementation of the different manufacturers of multimedia products and application interoperability, etc.
　　
2.IP video conference system with traditional video conference system comparison
　　
Previous traditional video conference system is based on a special line of protocols that need fixed H.320 routing and QoS assurance of video conference system. Mainly uses ISDN or E1 access. While the image quality of the sound ideal, but the user-end equipment and MCU (multipoint control unit) of expensive, small businesses and individual users will not be accepted.
　　
Since H.323 and H.320 agreement protocols (IP video conference system protocol) in the video, audio compression protocol on basically the same, therefore, in the same bandwidth situations, H.323 videoconferencing (IP video conference system) and H.320 videoconferencing quality basically the same.
　　
For ISDN access desktop H.320 videoconferencing, user terminal needs and fixed ISDN line binding that cannot be moved, in addition, if the convening of a meeting across provinces, users also need to pay long distance charges, not only in inconvenience to the users, also increased the burden on users. And H.323 videoconference system (IP video conference system) you do not have these problems because, for Internet users, there is no question of long distance charges, and, as long as H.323 video conferencing users are installed on the PC client software, compression card and camera, and a successful landing on the Internet, the Gatekeeper (gateway) registered, can by MCU (multipoint control unit) convene meetings anytime, anywhere, is very flexible and convenient. The user saves a tremendous amount of investment and maintenance costs, greatly improving the efficiency of the enterprise's information and communication; on the other hand also for operators to attract users, development of new value-added services.
　　
Initially, because the IP protocol is not very common, based on the ISDN line, in line with the agreement of products covers H.320 major proportions, with few years of the universal application of the IP Protocol and the rapid development of the Internet, especially for broadband network foreseen, in line with the H.323 protocol products since 2000, the overall proportion of markets has risen dramatically. Estimated in 2003, based on the H.323 protocol product sales will exceed the H.320 products.
　　
3.IP composed of video conference system
　　
According to recommendation H.323 IP video conferencing system from Conference Terminal (Termial), gateway (gateway), gap (gatekeeper) and IP networks, and multipoint controller (MCU).
　　
The Terminal is the provision of one-way or two-way real-time communication client. All voice communication terminal support, optional support for video and data communications.
　　
Gateway for achieving and non-terminal of H.323.
　　
Gatekeepers perform secure data network integrity features, including address conversion, access control and bandwidth management.
　　
High speed IP networks: as home users increased demand on Internet as well as for information exchange and higher requirements for high-speed IP network will get a fast development, through the re-laying 5 cable, users can gain access 10M even 100M bandwidth, you can fully support Conference TV business. Use of VLAN switches instead of hubs, support IGMP router, via frame relay and ATM network transfer images, guaranteed bandwidth, you can better guarantee the transmission quality video conference.
　　
Multipoint controller is used to support three or more points on a network, from the necessary multipoint controller (MC) and zero or more multipoint processor (MP). MC determines all terminal of audio and video processing power and control conference resources. MP mix, Exchange and processing of audio, video and data streams.
　　
Multipoint session is divided into a centralized, distributed and mixed multipoint session three modes.
　　
Centralized multipoint session must be equipped with MCU. All of the Terminal to ad-hoc manner to the MCU sends audio, video, data and control flow. MC Central Management Conference. MP for audio mixing and video mixing and data distribution, and ECHO participated in the meeting of the Terminal. Centralized multipoint meetings allow all come from different manufacturers of H.323 Terminal to join the meeting.
　　
Decentralized multipoint session using Multicast technology. Participation in meetings of H.323 terminal will be audio, video streaming radio to other participation in the meetings of the Terminal, control the information you send in a point-to-point manner MC. Receiving terminal is responsible for processing the received audio and video streaming. Decentralized multipoint Conference on network resources, and can significantly reduce costs. It called on the network configuration supports network broadcast.
　　
Hybrid multipoint session combines centralized and decentralized multi-point conferencing multipoint characteristic. Participation in meetings of H.323 terminal will be audio, video, stream select one point-to-point sent to MC, leftIn order to broadcast sent to all h.323 Terminal.
　　
By MCU can be centralized multipoint conferences and mixed multipoint conferencing, you can achieve greater flexibility.
　　
In addition, H.323 defines "loose" Conference to support large-scale meetings. In this mode, the participants were divided into active participants and passive participants, active participants are divided into permanent and temporary members. Passive participants will only be able to watch the Conference. Through temporary members and passive participant role change, allow more participants to express their views.
　　
II. Introduction to soft-switch technology
　　
1. the softswitch network architecture and implementation
　　
Soft switch controllers (Softswitch) is the softswitch system control core, it is independent of the underlying hosting agreements, mainly through call control, media gateway access control, resource allocation, protocol processing, routing, authentication, billing, and other major features that can provide the user with an existing network to provide businesses, and provide to the service support environment for the underlying network capabilities of the provider. Application server is the softswitch system in the body of the business support environment, business, development and management of core. Softswitch network system as shown in Figure 1
　　
Softswitch network from functionality can be divided into business plane and control plane, transport plane and access plane.
　　
Access plane offers a variety of networks and devices access to core backbone of ways and means, including the Signaling Gateway, media gateway, access gateway and other access device.
　　
Transport plane is responsible for the provision of all signaling and media stream transmission channel, the network's core transmission network will be the IP packet network.
　　
Control plane mainly provides call control, connection control, protocol processing capability, and provide access to the business plane underlying various network resources of the open interface. The main component of the plane is soft switching equipment.
　　
Application of the various plane using underlying network resources for users with a variety of network services. Including the application server (Application Server), strategy/management servers (Server Policy), AAA server (Authority Authentication and Accounting Server). The most important function of the entity is the application server, it is a soft switch network systems business execution environment.
　　
At present, about the softswitch network system interface between the various entities that have not yet finalized, but has some consensus reached on the information industry Ministry also has a related draft standard. Signalling, SS7 signaling through the signaling gateway into the IETF SIGTRAN signaling as and soft-switch between interfaces, soft switching equipment through ITU-T and jointly developed by the IETF Megaco/H.248 control media gateway and access gateways, soft switching devices developed by IETF SIP-T Protocol or the BICC ITU-T protocols for communication. And soft-switch device and the interface between the application server, currently highly recommended with open API (application programming interface) specification, for example by Parlay organizations to develop standards of Parlay API. Media, media gateway to traditional fixed and mobile networks for voice Pack component group to RTP stream in core IP network transmission.
　　
Softswitch with layered, open architecture, the traditional switch function module into independent network entities, entities adopting open protocol or API interface, which breaking the traditional telecommunications network closed pattern to achieve a variety of integration between heterogeneous networks. Next generation network system by business and call control and call control and the hosting, to achieve a relatively independent business system that allows top business and underlying heterogeneous network-independent, flexible and effective implementation of service provision, in order to be able to meet the diverse and evolving business needs. It can be said that the softswitch perfectly embodies the business drivers of thoughts and ideas, to achieve a fusion of multiple network, provides open and flexible business systems.
　　
Softswitch main processing real-time business, including voice, video and multimedia, and other business, it can be used for IP network, ATM networks, data communication network, can also be used for circuit-switched network. Soft switch used in IP network is natural, because IP networks of call control and hosts connections are separate. From the application, the softswitch is mainly used in IP network.
　　
Softswitch implementation is issued through the gateway, signaling control voice and data service Interworking. Signaling Gateway (SG) will convert SSN7 signaling IP signalling or IP based communication requests to signaling control media gateway data communication, media gateway (MG) is responsible for the telephone exchange network in PCM stream packet with the IP network. SG and MG are subject to the media gateway controller/call agent (MGC/CA) control, here, SG, MGC/CA and its subsidiary databases and complete functionality is a soft switch.
　　
Media gateways for processing circuit switched and IP network interworking of media information. H.248 Protocol, in MG entities through different networks with different media information conversion. H.323 protocol similar functional entity is MM (Media Mana-ger), in MG or other gateway is responsible for circuit switched network media (PCM stream, etc.) are converted to H.323 media (RTP/RTCP).
　　
Signaling Gateway is responsible for circuit switched network signalling into IP network signaling, according tothe corresponding signalling generated IP network control signalling in IP network transmission.
　　
Media Gateway controller/call agent is responsible for controlling the IP network connection (including the call control feature). MGC/CA is an important part of softswitch and feature sections. MGC is H.248 Protocol on MG media channel in the call State of the control section. MGC to H.248 Protocol or Media Gateway Control Protocol (MGCP), media device control protocols (MDCP), MG, CA by MGC/H.323 or SIP connections. The local Exchange Network (LS) including local circuit switched networks and SSN7 network, etc.
　　
Because softswitch to achieve various signalling between protocol conversion, therefore, it needs to support SSN7, ISUP, SIP, H.323 and MGCP protocols.
　　
Softswitch is a next-generation network control function entities for next-generation network offers real-time performance requirements of business call control and connection control function, is a next-generation network call and the control of core. Softswitch, NGN architecture is the key technology, the core ideas are hardware and software, through the software to achieve the original switch control, continuous and business processing and other functions, the various entities through standardized protocol for connection and communication for the NGN faster realization of all kinds of complex protocols, providing business more easily. Soft switching equipment is the more logical functional entity collections, providing comprehensive business call control, connectivity, and part of the business function is NGN voice/data/video business calls, control, business core equipment.
　　
2. soft switching function
　　
(1) provide support for a variety of signaling protocols (including H.248, H.323, SIP, SCTP, ISUP +, INAP +, RADIUS, SNMP, etc.) interface, the realization of the PSTN network and IP/ATM network signalling interworking and interoperability between the gateways.
(2)from the current application's point of view, a soft switch first to support voice business, followed by providing value-added services and additional services.
(3) provides programmable, logic control, open API Protocol implementation and interoperability of the external application platform.
(4) gate features, including access authentication, address resolution and bandwidth management function, and billing functions.
(5) the softswitch competitiveness mainly in software, it can be used as stand-alone NGN network components distributed across the network, for all media provides essential business and additional services, and other enhanced operational node, form new product form.
(6) in the circuit-switched network, softswitch and media gateway and Signaling Gateway combination, complete control of the conversion and media access conversion, tandem and changtuju access, provide the existing PSTN network basic business and additional services.
(7) in the circuit/group online, softswitch undertake with grouping Terminal, enabling packet network intercommunication and the circuit switched network Interworking.
(8), smart online, softswitch and media gateway functionality combined with complete SSP, and intelligent network SCP medicine offers a variety of smart business.
　　
After several years of development, a soft switch technology standardization and industrialization work also made remarkable progress, some old protocols such as H.323, MGCP, and constantly improve the mature, BICC, SIP/SIP-T new agreement also has introduced, based on soft-switch technology products has gradually entered the practical stage the NGN softswitch to become the most active and popular topic.
　　
Currently, many companies and manufacturers have already launched a soft-switching equipment, soft-switch to next generation networks for voice, data, image and communication play an important role, it is clear that its control will become the key technology of NGN, and become the technology of the hot spots, with broad development prospects.
　　
3. supports IP video conferencing softswitch system structure
　　
Because of the importance of video conferencing, and soft-switch system from several key aspects to take into account the application of video conferencing support. First of all from the network, the multimedia application processing and call mutual separation, video conference-specific information processing capabilities in the media server and intelligent terminal equipment, and universal call control and business in a soft switch device and the application server. Secondly, from the agreement, the H.323 protocol itself is developed for multimedia communications, SIP protocol is also constantly improving on the support of multimedia capabilities. As the cornerstone of soft-switch system media gateways, H.248 Protocol, you have defined a multimedia area expansion pack, is currently perfecting H.324 protocol to H.248 Protocol mapping. Finally, from a business capacity, opening up of service creation and delivery environment allows multimedia applications development richer and quicker. At present, to PARLAY-based API application interface elaborates multimedia applications function set, and with the voice, data and other applications.
　　
Support video conferencing softswitch system discards the H.320/H.323 conferencing system used by the integration of the MCU mode, Adaptive packet switching hosts a network of open features and advantages. You can use the following two new hierarchical mode so that it can better meet the needs of the operator's profit. The first mode is the separation of the MCU, MCU main programme by MC and MP, MC to control functionality, MP focus on media handling capabilities. Separation of the Center is divided into two parts, control MCU and media processing part separation, the two parts of the original use of the internal interface is a private interface. After the separation, the two parts of a standard agreement H.248. The second model is the integration programmes, which is due to the isolation of the MCU, MP device can be used as a media server in media resources. In the next generation network systems, in soft swap device control to continue to use. MC equipment and optional GK equipment is fully accessible by soft switch device and the application server instead. Separation scheme features relative to the fusion programme, soft switching device can fully control the media server. Therefore, the partiesCase with flexible business capacity, able to take full advantage of the open softswitch service interface for easy operator of integrated IP multimedia video conference. Multipoint processor (MP) is mainly responsible for IP video conferencing, voice, video, data, mixed, switch and synchronization capabilities. In addition, it also has voice encoding conversion feature. Multipoint controller (MC) mainly through a conference call and video conferencing control functions, centralized management for meetings. It can control multiple processors and the Terminal for voice, video, data, coding and decoding of coordination and priority setting, etc. Adapter gateway is responsible for receiving and processing data from non-user terminal of signaling and media such as audio, video, stream, and can handle one or more media streams, through the relevant processing and sent to the corresponding MP or user terminal. User terminal sends signalling message map to the corresponding message, the gateway to the soft switching equipment. Media Server can provide a dedicated media resource function, such as voice announcements, digital receivers, etc. At the same time, to meet new business requirements, Telecom also can support personalized dynamic sound programming, support resources, such as dynamically load and modify. Support for IP video conferencing softswitch system access, transmission, control and service four plane's main function is as follows:
　　
Access layer provides extensive network and terminal equipment access, including with existing network using various terminal (H.324 terminal as well as other types of terminals, etc.), intelligent terminal devices (e.g. SIP H.323 Terminal, Terminal, Terminal, Terminal H.248 MGCP and soft Terminal, etc.) and media server, etc. For H.324 Terminal, adapter gateway with the Media Gateway Control Protocol of the mapping function, while the information format conversions become able to group network of information formats.
　　
Transport-layer uses packet switching technology for packet-switched network, typically consists of an IP router or ATM switches, and soft-switch system provide a high reliability, raal unified and integrated transport platform.
　　
Control layer consists of a soft switch, the main implementation of call control and connection management, the dominant network resources, is responsible for the corresponding business process information transfer, and to the business layer provides an open service interface.
　　
Business layer primarily means for users to provide a variety of business and service equipment. It uses an open, integrated service access platform for next-generation network offers a variety of value-added services, video conferencing, as well as third-party business. At the same time, it also has the corresponding service creation and maintenance of the environment.
　　
IV. application to the IP video conference software switch functionality of the device should have
　　
In order to support IP video conferencing, soft switching equipment should have more control features to support the following features:
　　
(1) to support the call handling features: implement Terminal to join and exit IP video Ad hoc meetings, including Non Ad hoc manner and way of meeting; provides dynamic modification of call and connection; you can communicate at any time add to or delete the communication party, without disrupting other call connection; should be able, and video multimedia terminal for voice/video coding and decoding of negotiated.
　　
(2) session control function: to control MP and video multimedia terminal building on/off the sound, video and data logic channel; to support the President Conference control methods, including viewing venue, automatic browsing, applications/release President, disconnect/add venue, venue, mute/unmute, venue mute/cancel mute, Radio Hall; when the Chairman of the control to apply to speak of "token" Terminal assignment, follow the "token" holder's directive to control the video signal; MP switch can control the way the President controls MP and voice control to switch between modes.
　　
(3) the resource control function: should be able to video multimedia terminal requests on various media MP conference resources, including voice codec resource, multi-channel voice mixed resources, video codec resource, data focus on resources, etc.; shall be able to control MP report resource usage information, receive MP report due to a fault, restoration or management of the physical entity of state changes. These physical entities can include vector endpoint, media resources, etc to MP instructions specific to a meeting of the resource or resources collection.
　　
(4) QoS management functions: should be able to control the jurisdiction domain MP, reports its status information, such as system resources usage, status information, breaking, codec types, bandwidth, etc. Can control MP on voice and video processing, such as the cache size, audio/video codec, echo cancellation, silence compression, comfort noise, speed, etc.
　　
(5) certification and authorization features: should the jurisdiction of the MP for authentication and authorization to prevent illegal access to the device. Be compatible with the certification system complete multimedia user session authentication. On the user's authentication including user ID, account password,the user class, meeting ID, meeting password, business type, etc.
　　
(6) Protocol features: support for the H.323 protocol, SIP, series H.248 protocol MGCP Protocol and communication between the multimedia terminal; support H.248 Protocol control MP and media server; support for SCTP fluidic transfer protocols available SCTP protocol transport H.248 protocol data; support H.248 Protocol control adapter gateway for H.320 Terminal and H.324 terminal access.
　　
In addition to the above function with multiple-point control, softswitch also has traffic detection. In management, a soft switch should be able to configure, test and control various intelligent terminal equipment flow function to avoid various intelligent terminal equipment without restrictions on the use of bearer network bandwidth resources, and support for the specified grouping device traffic statistics, on a variety of intelligent terminal equipment available bandwidth limit configuration and configure the bandwidth exceeded the upper limit of equipment in the business. On peer to peer video conferencing, a soft switch, you can press the session time and billing, you can call each media type of session duration respectivelyBilling or toll on traffic, i.e. session each media type flow billing respectively. Can be combined billing for voice long-time billing, video or data traffic billing, etc. For point to multipoint video media business, softswitch billing as session length, you can separate the multi-segment metering, or to call in each media type in the respective billing call time. At the same time, can also be toll on traffic, you can separate the multi-segment metering, you can also press call flows and billing in the media.
　　
V. IP video conferencing in the softswitch network implementations
　　
1. point-to-point IP video conference on the implementation of
　　
Point-to-point IP video conference with the General call, is still a caller and a called user participatory process to complete the call, but multimedia streams at the same time contains voice and video. Therefore, the soft switching equipment, its control of the process is basically the same as ordinary call. Only in the following two differ first gateway/terminal control process is slightly different, point-to-point videoconference increased control of the video stream. Second, such a control protocol used by the process may be different. Point-to-point IP video conference involving the H.323 protocol or SIP protocol or H.248 Protocol. From a practical perspective, point-to-point video conferencing should be the normal telephone terminal mutual call. Since the ordinary telephone terminal does not have the video function, so the call must be shielded video multimedia terminal video capability, only pure voice. This requires the softswitch equipment according to the master of the called user, in particular, the called user terminal capacity to decide a particular type of call.
　　
2. point-to-multipoint IP video conference on the implementation of
　　
Point-to-multipoint video conference set up Ad hoc and Non Ad hoc. Non Ad hoc way refers to softswitch network prior to the Conference set aside resources, until the specified time, all participants can dial a special conference number to join the meeting or the soft-switch the call to join. Ad hoc mode is a sponsor of the Conference, to invite those who want to participate in the meetings of the Terminal to join the meeting. Meeting of the provisional allocation of resources according to need. Ad hoc manner as Non prior to reserve conference resources, so you can ensure the success of the meeting. But because of the various properties of the Conference have agreed in advance and cannot be changed, so the less flexible and more complex. Ad hoc manner without reserve conference resources, but temporary dynamic allocation on an as-needed basis, it may be because the softswitch network meeting resources are insufficientand cannot be successfully established. However, since the meeting initiator can be invited to join the meeting on any terminal session, change the properties, so relatively simple and flexible.
　　
Non Ad hoc way of meeting application, require prior adoption of a way to book a meeting, attended by all the participants at the Terminal, the President of the Conference, meeting, voice/video/data property and other relevant parameters. Conference calls can have Dial-in, Dial-Out manner. Non Ad hoc way of meeting the needs of the application server. Application server provides the features of the business of the meeting to order, Conference control (such as a mix of voice, data, image, switch, etc.). It is through the soft switch device control Conference Media Server reserved conference resources. Session establishment, each terminal to join through the application server authentication.
　　
On the Ad hoc mode of application, the meeting of the Conference of the sponsors of the Conference do not need to be booked in advance, but by calling softswitch request a meeting. Soft-switch based on a meeting request to a participating terminal a invite to meetings, and dynamic resource allocation for the meeting. Session establishment, the sponsors of the Conference or the Chairman can continue to invite other Terminal to join the meeting. Ad hoc mode, the session is in the basic call extended on the basis of, and does not require a dedicated server that can be used by the softswitch device directly to the complete session control functions.
　　
Softswitch network Conference control typically have President control mode and voice control. When the session is established, the default mode is the voice control. Meeting a build, all the terminals and media server on the establishment of a good logical channel, including bi-directional voice, video, logical channel and data channel. Terminal to send and receive audio, video and data media from soft-switch based Conference control send related directives to control.
　　
In the resolution of the fixed network voice business, softswitch network is very mature. But in the field of IP video conferencing, softswitch network is in its infancy, in order to meet the next generation network, must extend its application to the multimedia area, due to factors such as the image, in the Terminal, business, resources, and other aspects than simple voice services to demanding many. At this point, a soft switch must have a multipoint session control, information exchange control, control function, support and multimedia terminals, multipoint controller as well as multimedia gateway, and other protocol interface for various video conferencing.
　　
IP video conferencing areas of focus to make the market priced transfer user market. From the communications market development we can see that most of the product's target market user are from high-end users to low-cost user gradually shifted. Due to the technical level and the improvement of the production process, the cost of these products, and gradually reduce as the application area of expansion, the scale effect in this area. In this way, the video conferencing system from high-priced private market to low-cost market gradually over an ordinary user. Soft-switching technology for next generation network voice services, data services and video services call, control, business provides one of the core technologies that will effectively promote multiple IP video conference application and development.