Text messages don't display content.

I often receive a kind of short message, that is, there is not a word in the short message, which is normal, because the person who sent the short message did not edit the content of the short message at all, or sent it without editing the content of the short message. I've received messages like this before, from my father. At that time, he was still using the aging machine, could not operate the mobile phone, and clicked the keyboard. When asked, he said that he didn't even know how to send it.