How to charge for sending short messages in groups?

SMS charges are prepaid, each SMS charges 0. 1 yuan, and there is no extra charge. Mobile phones require China Mobile and China Unicom, covering all parts of the country, and the number of group calls is unlimited. After the fee is deducted, the service will stop. The length of a message is 70 Chinese characters (including spaces, punctuation and symbols), more than two, which can provide detailed information for customers' cost inquiry.