How does China Unicom know its short number?

You can query the Unicom virtual network short number through the following two methods: 1. SMS method: send the text message content "CX" to "10019" to query the local virtual network short number and remaining short numbers. No. time. 2. Dial the query system: Dial 4000 to enter the management process. The following instructions are for reference: Dial 4000 from the China Unicom virtual network mobile phone, and the prompt is: "Welcome to the China Unicom virtual network query system. For business management, please press 5. To exit, please press 0." If you press 5 , then play: Please enter your personal password and end with #. If the password entered is correct, the system will play: Please press 3 to query the user's long and short number, press 4 for personal password management, and press 0 to exit. Press 3 to enter: Tips: To query the long number for a short number, press 1, to query a long number for a short number, press 2, and to return, please press other keys. Press 1 or 2 to query relevant information based on the user's short number or long number respectively. (The initial password is 1234 or 88888888. If the user needs to accurately query the VPN password, he or she must go to the China Unicom Business Hall to check)