How to send text messages with that mobile satellite?

The principle of satellite communication is as follows:

The radio signal was sent from a ground station. After the weak signal is received by the satellite communication antenna, it is first amplified, frequency converted and power amplified in the communication repeater. Finally, the amplified radio waves are forwarded to another ground station through the satellite communication antenna, thus realizing long-distance communication between two or more ground stations. For example, if a user in Asia wants to call another user in America on the other side of the ocean through satellite, he must first connect the user's telephone line with the ground station in the satellite communication system through the long-distance telephone office, and then the ground station transmits the telephone signal to the satellite. After the satellite receives this signal, it will be amplified by a power amplifier and then forwarded to the ground station on the other side of the Atlantic. The ground station takes out the telephone signal and sends it to the long-distance telephone office in the city where the receiver is located to transfer the user.

Satellite communication is simply the communication between radio communication stations on the earth (including the ground and the lower atmosphere) using satellites as the medium. Satellite communication system consists of two parts: satellite and earth station. The characteristics of satellite communication are: wide communication range; As long as it is within the coverage of radio waves emitted by satellites, communication can be carried out between any two points; Not easily affected by land disasters (high reliability); As long as the earth station circuit is set, it can be turned on (the circuit can be turned on quickly); At the same time, it can be received in many places, and it can economically realize broadcasting and multiple access communication (multiple access characteristics); The circuit setting is very flexible, which can disperse the excessively concentrated telephone traffic at any time; The same channel can be used in different directions or different parts (multiple access connection).