I bought a new Unicom flow card, and I can't send messages or receive them, let alone.

First of all, you can take out your mobile phone card and put it in someone else's mobile phone to see if you can send and receive short messages. If you can, you can prove that your mobile phone card is ok. For mobile phone problems, you can check the instructions of the mobile phone terminal or contact the mobile phone after-sales for detailed understanding.

Secondly, if you still can't send and receive SMS normally, and the number of SMS center is set correctly, you can contact local customer service or go to Unicom's independent business hall to confirm whether the SMS function of this number card is opened normally.