Why do I have to deduct money every time I send 200 SMS messages 10 yuan?

I'm here to give you a positive answer: in fact, whether China Unicom sends a mobile phone or China Unicom sends a mobile phone, it also says that it's the same for each other. If there is a monthly subscription, calculate it first, and deduct the money if it exceeds it. When you say "deduct money", you should show the content of SMS consumption when checking the phone bill, right? But in fact, when you actually deduct money, you don't deduct it unless you exceed it, which is just for the convenience of record. Please be careful.