Why does Motorola A3 100 always prompt that one or more recipients cannot be recognized or the address is invalid when sending short messages?

If you can't send or receive it in a short time, you need to fill in the "SMS Center Number" again first. You can call 10086 for consultation. If it still doesn't work, there may be something wrong with the setting of your mobile phone in this province. I suggest you try clearing the main reset. The password is six zeros. Good luck!