Excuse me, I use a mobile card. I can call to receive short messages, but I can't send short messages. It keeps showing that the SMS has not been sent. Why?

It's simple. You should change your phone first. If your mobile phone card can send text messages in other people's mobile phones, it proves that there is something wrong with your mobile phone settings. Then you can go to the mobile office and ask the staff to help you. If you can't send it after changing your mobile phone, call 10086 to ask if it belongs to the SMS blacklist. If yes, please ask the staff to record and solve the problem. If not, it depends on whether you can't send text messages to fixed numbers or all numbers, and when you can't send text messages to which mobile phone number, and record and tell the staff what the prompt is, and ask the staff to help you record and verify it.