What does the basic fee of short message center (telecom C network) mean?

SMS Mobile Interoperability Foundation Fee: refers to the fee charged by users of one communication operator to send SMS to users of other communication operators (including SP service fee for SMS opening, specifically, you need to call 10000 or bring your ID card to the business hall to inquire about the opening service. If it is not necessary, it can be cancelled to avoid next month's deduction).

Short Message Service (SMS for short) refers to the text or digital information directly sent or received by users through mobile phones or other telecommunication terminals. The number of characters that users can send and receive SMS at a time is 160 English or numeric characters or 70 Chinese characters.