Introduction and application of VoIP technology
Voice-over-IP (VoIP) is a new type of telephone communication technology that uses the Internet Protocol (IP) to transmit real-time voice over the Internet or other IP networks. In this IP telephone communication, the long-distance transmission of voice is performed by the IP network. Therefore, the traditional long-distance communication service fee can be omitted or even eliminated. In IP telephony, the two parties use a technical device called a voice gateway to act as a bridge between IP networks, and complete the call process by installing a voice gateway from an ordinary phone to an ordinary phone.
The VoIP network uses the packet switching technology based on the IP protocol. The biggest advantage of this technology compared with the traditional telecommunications switching network is that it can make full use of the network hardware resources so that more people can use the same hardware resources at the same time. Although this advantage is sometimes affected by line quality and network bandwidth allocation, the huge economic benefits and market opportunities it brings have attracted the attention of all walks of life worldwide. According to the authorities Frost and Sulliuan predict that by 2002, the monthly IP telephone traffic will reach 8 billion minutes. The US government first announced that it cannot restrict the development of Internet telephony or IP telephony services, and China has also included IP telephony in its national development plan.
Principles of IP telephone communication
IP telephony is an emerging industry. The so-called IP is the Internet Protocol, that is, the Internet protocol. The method of transmitting voice over the Internet is called IP telephony.
The principle of IP telephony is to convert the analog signal of a normal phone into a digital signal, compress and package it, transmit it through the Internet, decompress it after reaching the other party, and restore it to an analog signal. The device answers.
IP telephony uses this communication technology to reduce the cost of international long-distance calls. However, due to the use of compression, packaging, and reduction technologies, all IP phones currently have delays. For users, the international long-distance call itself has a delay, so users can accept it.
Currently there are two main types of IP telephone gateways on the market. The first type is to insert voice boards on some models of routers, and the router itself becomes an IP telephone gateway. There are three typical ports on this type of router: the LAN port connects to the local network, the WAN port connects to the router at the other end of the WAN, and the voice port connects to the telephone or program-controlled switching equipment. The second type is a separate IP telephone gateway. This type of gateway has only two interfaces, one is a LAN port connected to a hub, and the other is a voice port connected to a telephone or program-controlled switching equipment.
In comparison, if the first type of equipment is directly connected to the wide area network, it will no longer pass through the local network (LAN) when transmitting voice / fax, reducing one link, and the delay will be less. However, the transmission rate on the LAN is generally 10Mbps to 100Mbps, so the actual situation will be different. The first type of gateway also has weaknesses. First, there is a single point of failure. Second, all the work of complex voice sampling is handed over to a small and medium-sized router. The load may be slightly heavier. In contrast, the second type of gateway equipment is more flexible and eliminates single points of failure 
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