SMS input method is a mess.

1. Can you adjust the font and code on your mobile phone? If you have this option, please set it as the system default.

2. Have you sent photos? It is also possible that the other party does not have the function of receiving pictures, and the pictures will be decoded into garbled codes.

3. Is yours a smart phone? Have you installed some software with fonts and decoders? Such as e-books, electronic comics, etc. Uninstall them, and then try sending SMS again.

4. Have you installed the input method on your mobile phone? Does the input method come with fonts and decoders? Try to uninstall with the system default input method.

That's the general reason. If not, it is a network problem, and there may be packet loss. There are binary files lost in SMS transmission, which is the operator's problem.