10086. What do you mean?

This is very clear. Charge the phone bill to participate in an activity, which is a discount based on your monthly phone bill. That is to say, after participating in the activity, you dial a specific number (usually the number you agreed or the number they sent you a mobile phone) and generate a certain amount of phone bill, and then they send you the phone bill promised by the preferential terms. If you promise to use a certain number to generate a phone bill, but you don't actually use this number to make a phone call to a certain number, then they can't send you a phone bill. So they urge you to call at that number.