Principle of Public network Intercom

Push-to-Talk Over Cellular (PoC) is a communication system that transmits voice signals through the data channel of mobile phone network signals to implement intercom calls. Simply speaking, it is based on the communication function of telecom operators and the third party intercom system. Public network walkie-talkies are like wechat, which uses telecom network traffic to chat. SIM card is responsible for signal and traffic, intercom system to achieve a variety of functions, such as voice, group chat, private chat, positioning, video and so on. It solves the real-time performance of intercom and error-free transmission of PTT signal, thus solving the problem of short distance of traditional intercom due to the constraints of transmission power and antenna sensitivity, and realizing intercom nationwide and even worldwide.

History of public network Intercom

The first PoC solution appeared on the market shortly after the Open Mobile Alliance (OMA) published its first set of PoC specifications in June 2005. Since then, PoC has grown somewhat in North America, using 2G services and then switching to 3G, but adoption in Europe has been slow. However, the PoC development landscape has changed dramatically in the past two to three years with the launch of commercial 4G LTE networks. 4G networks have higher data speeds than PMR technology. Because of this,PoC technology is an attractive solution for many (though not all) organizations, especially for customers with non-mission critical communications.

In our country, PoC in the initial stage of development is also very slow, there are three reasons for: 1, the public network talkback belongs to new things, but also in the research period, the user acceptance is not high; 2, the profit of walkie-talkie is much lower than that of mobile phone, thankless, unwilling to invest too much research and development effort; 3. At that time, the flow cost was not cheap, and it was difficult to popularize. Later, in 2008 gradually had a turnaround, according to the structure agreement signed by Unicom and telecom on June 2, 2008, CDMA network and affairs will be transferred by Unicom to Telecom on October 1, 2008, when China Telecom officially operates based on CDMA business, after the reorganization of Telecom mobile phone users that CDMA users will have more than 40 million. In September 2010, China Telecom launched QChat (Tianyi Intercom), which was commercially tested in Shanghai World Expo and Guangzhou Asian Games. In 2011, the number of users exceeded 50,000, and public network intercom began to serve the Chinese government, enterprises and institutions in a large area. On December 4, 2013, the Ministry of Industry and Information Technology officially issued 4G licenses to the three major operators, which meant that the three operators could start to operate 4G network services, and the 4G era began. Taking this opportunity,4G walkie-talkies also began to emerge. In 2015, with the gradual popularization of 4G network, the price of public network intercom began to decline and the sales gradually soared. Public network intercom played a clarion call to replace the traditional intercom. More and more short distance intercom users such as property and hotel began to choose public network intercom From this we can draw a simple conclusion, why the initial public network walkie-talkie did not develop well both at home and abroad? One of the most important reasons is that the data carrying capacity of 2G network is limited. After the gradual development and popularization of 3G and 4G, users naturally vote for the public network intercom with their feet. There are two reasons: one is that the communication function of public network intercom is compared with the traditional pair.There has been a significant improvement of the telephone (call distance, sound quality clarity, confidentiality, positioning, grouping, single call, etc.); One is that the traffic rate has been close to the cabbage price, users using the public network walkie-talkie will not bring very heavy financial pressure. It's easy to use and cheap, so why not?