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IP-telephony in the first stages

Submitted by on Wednesday, 19 June 2013No Comment

In its development of IP-telephony was three stages. At first it was, rather, Internet-toy, suitable only for kvakayuchoho and hissing for two enthusiasts. Two computers equipped with microphones, speakers, sound cards and for digitizing sound and not very sophisticated software, allowed to maintain two-way dialogue via the Internet in real time. But to comfort the public telephone communication services thus clearly nedotyahuvav.
Clients need to know IP-address of the computer conversation, agree on a call, select the time for higher quality transmission of language, when Internet traffic between specific data points are not encountered major delays and overload. Furthermore, the absence of standards on both computers must be set the software to voice encoding and packing it in bags was the same. Interaction between a computer and a telephone connected to the public telephone network is not expected. But costs a small fee limited providers Internet.
The second stage was marked by the emergence of standards for IP-telephony, especially – Group standards H.323. Developers of these reports came out that the two networks – phone and IP – spivisnuvatymut alongside quite a long time, so it is important to regulate their interaction with the connection subject to the procedures that exist in traditional telephone networks, and agree how to transfer the call and vote on the same network IP.
The standards H. 323 is determined by two groups of protocols – the protocols of the transport plane (transport plane), called also assigned to the user plane (user plane), and call control plane protocols (call control plane). Minutes of the transport planes involved in the direct voice network packet switching and call control plane protocols to carry the network requests to establish connections and implement service features such as authorizing subscriber access to network and connect time accounting. The main elements of the network H.
323 is the so-called IP-phones that connect directly to the IP, and gateways (gateway), that connect traditional telephone networks with IP and provide broadcast in packages and often kompressyrovannoho digitized voice into digital or analog form, suitable for transmission via telephone network. In addition, the gateway function H. 323 is broadcast telephone network signaling protocols, such as R2, Q. 931 or SS7, signaling protocols in the stack H. 323. Gateway allows subscribers with a regular telephone device to communicate with users of IP-phones or use IP network as a transit.
The main objective level of challenges – to choose the way in packet switching networks – in the simplest case, the gateway can be solved, but in a more general statement charged the special network element – guard (gatekeeper). Watchman performs registration and authentication of subscribers, if necessary address translation (eg, DNS names in phone numbers) and is routing calls to the IP-phone or gateway, and if necessary, then to another keeper. Usually a keeper maintains the so-called zone of the network is under the administrative control of one organization. All functions in the architecture keeper H.
323 can perform and terminal devices – phones and gateways, but this decision was badly scaled and the flow of calls and barely controlled prices.
At this stage of IP-telephony network IP (Internet or private) are widely used as a transit between two local telephone networks. This scheme of public services to IP-telephony has become quite popular worldwide, including in Russia. To implement its operators do not have to create his own way

Source: ip-kuban.ru