Dear gods, how does Unicom send a text message to check the monthly rent?

Unicom's mobile phone can query its monthly rent in the following ways: 1, and SMS query: the mobile phone sends SMS instruction "208 1" to 100 10 (sending SMS is free) to query its package; 2. Telephone self-service voice inquiry: this machine dials the Unicom customer service hotline, presses 1 according to the voice broadcast, and then presses 4 to inquire about the local tariff; 3. Self-service inquiry in the mobile phone business hall: log in to the mobile phone business hall of China Unicom through the local machine and service password, and inquire about the current package and monthly rent through "Service-Inquiry-My Basic Information"; 4. Online business hall self-service inquiry: 1) Log in to the online business hall of China Unicom through the local phone number and service password, and click "Self-service". 2) Click the avatar at the top left of the screen to pop up a dialog box, displaying information such as "My Package", and you can query the monthly rent through the displayed content. 5. Manual inquiry: this phone calls the Unicom customer service hotline, and it is transferred to manual customer service according to the voice prompt, and the customer service representative provides it with the local service password. 6. With my valid ID card, go to the local Unicom's respective business halls to inquire about local tariffs. Tips: Due to the different SMS descriptions and inquiry methods in different regions, you can call the local Unicom customer service hotline for consultation.