Why does the mobile phone have no signal, but it can send messages but can't get online?

The mobile phone has no signal, but it can send messages, but it can't get online, because there is no signal here, but there is a communication signal. The network signal supports surfing the Internet, and the communication signal supports calling and texting.

At present, the networks of many communication companies are upgrading, which leads to the coexistence of multiple networks. When the mobile phone accesses the Internet, the priority order of the page display is 4G, 3G and 2G icons. Sometimes there is no signal. At present, there may be no 4G or 3G signal, but the background networking of the mobile phone is running at 2G, but the icon of the mobile phone has not been updated.

For example, China Mobile, GSM is a second-generation digital communication system, which supports voice, low-speed data and short message services, and its speed is very slow, that is, it supports words and small hazy pictures. But the coverage is very wide, and basically there are signals everywhere.

3G supports voice in standard definition format, pictures in medium definition and smooth video. 4G supports high-speed data services. It is more expensive to watch high-definition videos online, and the functions of voice services are still being improved. Therefore, when the mobile phone is operating, it needs to re-select the network according to the current network state. In this process, the mobile phone has been supported by the second generation GSM digital communication system.