The principle of sending short messages through mobile phones.

The principle of getting through the phone and sending text messages;

The frequency of mobile phone signal is very high, generally around 900Mhz, and it propagates through ionospheric reflection. Cell phone signals for calling and texting are transmitted to the nearest base station, that is, the mobile or connected cell tower, and then the base station reduces the frequency of high-frequency signals, and the base station communicates with the base station. This signal travels in a straight line, and it will be blocked when it meets tall buildings, so those towers are very high, which are transmitted to the base station near the mobile phone that answers the phone, and then converted into high-frequency signals for the mobile phone.

The full name of GSM system is digital cellular mobile communication system. In which area, the mobile phone will automatically track the nearest base station, so the above communication mode can be realized. Unicom's communication system is more advanced than mobile in theory, because GSM is the first generation mobile communication system and CDMA belongs to the second generation, which is the full name of narrowband code division multiple access digital access technology. However, due to the funds of China Unicom or other technical reasons, the signal in many areas is not as good as mobile.