This is just a sign of your M-Zone package. If you don't accept this 20 yuan money, it's equivalent to a trademark, so don't worry about the charges.
"Wuhan Dynamic Fashion 10 yuan SMS Discount Package"
That is, use 10 yuan to wallet 200 short messages in the network, and the excess will be charged at 0. 1 yuan, and PHS and Unicom numbers will be charged at 0. 15 yuan respectively.
If you don't call this month, the minimum monthly consumption is 16 yuan, SMS package 10 yuan, and the caller ID of 6 yuan.
This is what I use. I also opened 3 yuan wallet 100 SMS, which was quite cost-effective, hehe.
You can send zd to 10086 to check the charge deduction record of your mobile phone at any time during use (free of charge).