What is an IP phone?

IP phone refers to the application of real-time transmission of voice information through TCP/IP protocol on IP network. IP telephone started from PC-to-PC telephone on the Internet, and developed to connect the Internet with traditional telephone network through gateway, realizing IP telephone from ordinary telephone to ordinary telephone. IP telephone can be divided into four types: PC-PC, telephone -PC, PC- phone, telephone-phone and IP fax (real-time and store/forward).

IP phone is a digital phone. Compared with the traditional analog telephone, the voice signal is digitally quantized, compressed and packaged before transmission, converted into a data stream with a bandwidth of 8kbps or less, and then sent to the network for transmission. The traditional analog telephone is transmitted by pure audio signal on the line. Because IP phone uses digital form as transmission medium, it occupies less resources, so the cost is very low and the price is cheap. At present, the voice quality of IP phone is not satisfactory compared with analog phone, but with the improvement of Internet connection speed and technology, the voice quality of IP phone will be further improved.

What kind of IP phone is opened in China? What companies operate?

Terminal IP telephone service, that is, ordinary telephone to ordinary telephone, is operated by China Telecom, China Unicom and Jitong Company. What users need to do is to buy an IP phone card, just like 200 or 300 long-distance phone cards. Dial the IP phone access number on the phone (the IP phone access number of China Telecom is17900; China Unicom is17910; Jitong company is 17920), and you can make a phone call with the voice prompt.

The test scope of IP telephony services carried out by the three operators is: China Telecom in Beijing, Shanghai, Guangzhou, Wuhan, Xi 'an, Shenyang, Nanjing, Chengdu, Tianjin, Chongqing, Hangzhou, Fuzhou, Jinan, Changsha, Kunming, Harbin, Changchun, Zhengzhou, Shenzhen, Dongguan, Suzhou, Dalian, Qingdao, Xiamen and Zhuhai; China Unicom is located in Beijing, Shanghai, Tianjin, Chongqing, Guangzhou, Nanjing, Xiamen, Chengdu, Hangzhou, Fuzhou, Shenzhen and Dalian. Jitong Company is located in Beijing, Shanghai, Guangzhou, Shenzhen, Wuhan, Dalian, Qingdao, Dongguan, Xiamen, Tianjin, Ningbo, Hangzhou and other cities. There are three main forms of IP phone: 1. Computer to computer; 2. Computer to ordinary telephone; 3. Ordinary telephone to ordinary telephone. The first two forms need the support of computers and Internet terminal modems, while the third one does not need any additional investment.