My mobile phone is Nokia C5-3. Why can't I send short messages? Please help me explain what is going on and how to solve it.

1. It may be a problem with your mobile phone card. I suggest you call the operator's customer service number to check. It is possible that there is something wrong with your mobile phone settings. It is recommended to format or reset the settings. 3. I suggest you restart your mobile phone, send messages and send more people. If it doesn't work, it may be a network problem. 2. If all the above operations fail, I suggest you send your mobile phone to a specialty store for repair.