China Unicom's question answer: I received such a short message: Your credit line has run out, and you have been shut down. What the hell did I do? There is still a balance of 50 pounds,

"If the balance you inquired through Unicom's online business hall or mobile phone client does not exclude the remaining call charges of last month, but the real-time call charges of this month have not been deducted, if the balance of last month is not enough to deduct the real-time call charges of this month, and the credit line has been used up, you will be prompted to be stopped. Specifically, you can log in to Unicom's online business hall and choose local online customer service to contact manual customer service for verification. "