What associations can be realized between the primary card and the secondary card, and how to deal with the secondary card?

The primary and secondary cards of China Telecom provide users with both a primary card and a secondary card. The main and auxiliary cards realize combined payment, and the main card is used as the payment account. When the primary card user chooses the basic package, the secondary card user can enjoy the duration of voice, SMS, MMS, data stream and WiFi in the primary card basic package; The unified package implemented by the main and secondary cards exceeds the tariff standard; Local mutual discounts are provided between the primary card and the secondary card.