Broadband Ip Phone Technology Status And Development
With the deepening of Internet applications and development, IPoverASP? Column = news & key = broadband target = _blankclass = qqx_gjz> broadband on emerging new technologies, ISP, IC P, ASP and other Internet companies continue to emerge, promoted the sustained rapid growth in data services, the business much more than ordinary PSTN business trends.
IP will become the future information Communicate Leading technology, a variety of business by the IP packet to host (Everything overIP), and IP information flow can also send in a variety of transmission media (IP overEverything), and IP-based networks, and ultimately data, voice, image operations integration and network convergence. NGN to build a new generation of information using the network to provide voice, data and images integrated services, will become the goal, represents a new generation of 21st century communications network development. Broadband IP Phone (Note: the proposed text refers to ordinary broadband IP phone IP phones and IP video phone) is in this new Internet age developed one representative of the applied technology.
1 key technologies of broadband IP telephony
Broadband IP phone is based on the packet-based IP technology, digital transmission technology, simply is: via voice and / or image compression algorithm for voice or / and image data compression in accordance with relevant standards agreement encrypted, then the voice data by IP communication protocols and other related packages, through broadband IP network to transmit data packets to the receiver, the longer the voice and / or decode the image data packet decompression treatment, restored to original voice and / or image signals, so as to achieve the IP network to transmit voice and / or purpose of the image. Broadband IP Phone greatly improved network bandwidth utilization, significantly reducing communication costs, it also promoted the wider use of broadband multimedia applications. The biggest advantage is that can be widely used Internet and the global IP interconnect environment, providing more than the traditional business, better service.
Key technologies of broadband IP phone, including: signaling, coding, real-time transmission technology, quality of service (QoS) assurance technology, and network transmission technology, IC The development of technology.
(1) signaling, signaling to ensure the smooth realization of phone calls and voice or / and image quality, is widely used signaling system includes IT UT’s H.323 series and IETF’s Session Initiation Protocol and Media Gateway Control Protocol STP MGCP/H.248.
(2) codec technology, codec technology is a key IP telephony component. Speech codec currently the main technologies used by ITU-TG.729, G.723 (G.723.1) and other, image coding and decoding technology has the ITU-T H.263/H.261.
(3) real-time transmission technology, real-time transmission technology is mainly real-time transport protocol RTP. RTP is to provide-ended, including audio and video, including real-time data transmission protocol. RTP provides a time stamp and control characteristics of different data flow synchronization mechanism that allows the receiver side re-sends the data packet, can provide multi-ended to send the group to receive the service quality feedback.
(4) Quality of Service (QoS) assurance technology, IP phone, mainly in resource reservation protocol (RSVP) as well as quality of service Monitor Real-time Transport Control Protocol RTCP to avoid network congestion, protect the network transmission quality.
(5) network transmission technology, broadband IP phone, network transmission technology is mainly IP, TCP and UDP, also includes gateways interconnect technology, routing, network management and secure authentication and billing technology and so on.
(6) IC development technology, integrated circuit technology has a direct impact on how the development of broadband IP telephony. As the need for voice or / and image data compression, it must have high-speed, high-capacity DSP Or application specific integrated circuit support; because of the need to control more features, tasks, coordination, hence the need for faster, more complex, more powerful CPU Support.
2 broadband IP phone status Recent years, with Telecommunications Value-added services and the rapid development of broadband access, major carriers have built their own nationwide IP telephone network, for broadband IP phone provides a development platform, its development is very rapid. Many domestic and foreign companies, universities, research institutes have joined their ranks, the high, medium and low-grade program, the product category are particularly prominent. For general IP telephony, low-end products, mainly the United States, the program CentralityCommunications, MamaKall CommunicationInc., Plan high-end products are mainly the United States Polycom, TI, Cisco , Norway, TANDBERG. For IP video telephony, low-end products in the program are mainly South Korea C & S, PHILIPS, ADI, Winbond, etc. The program of high-end products are the United States, Polycom, Norway, TANDBERG. Most domestic and many manufacturers are using their second development program, and then form their own products. As the broadband IP phone
is only in recent years developed new products, its core technology is relatively mature use H.323 protocol. ITU’s H.323 series of recommendations defines quality assurance in non-business Internet or other packet network protocols and multimedia communication protocols. H.323 standard is a LAN, WAN, INTRANET and multimedia on the Internet to provide basic support, the encoding mechanism, scope of the agreement, and basic operation of the Q.931 ISDN signaling protocol similar to the simplified version, using the more traditional telephone exchange method. Related agreements, including for control of H.245, used to establish the connection H.225.0, for large meetings H.332, used to supplement the business H.450.1, H.450.2 and H.450.3, the security H.235, and capacitor switching operations interoperable H.246 and so on. H.323 offers between devices, between applications and operating high-level interoperability between operators. It does not depend on network structure, independent of the operating system and hardware platform to support multi-point capabilities, multicast, and bandwidth management. H.323 has considerable flexibility to support different functions of the nodes includes meetings and meetings between different networks. The proposed H.323 multimedia Conference System In the flow of information, including audio, video, data and control information. Information flow using H.225.0 recommends ways to package and send.
More mature as H.323, but also open source code
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