Why is my debt 10? I didn't send a message until 1.

Some systems are delayed. When the number is used for a certain period of time, there will be a credit limit, and a certain amount of arrears will be reminded.

If you stop the machine immediately because of arrears, you can't send text messages when you stop, unless it's a GSM overdraft, like an ordinary Shenzhou Bank, you can't receive it until your phone bill is fully charged, but you sent text messages before because the arrears of downtime were delayed.