The secondary card will immediately notify the main card of the arrears.

I will. The main and secondary cards share the phone bill, and the main card can query the consumption of the secondary card through the phone bill. In the case of insufficient phone bill balance, the main and secondary cards will receive SMS prompts.

What card do you use to charge the phone bill or receive information, because a number represents a mobile phone, which means that only my mobile phone will receive information when I recharge with a card. It is impossible for me to recharge the information and send it to someone else's mobile phone.

The operation of the secondary card will be prompted by the main card. Master cards for various packages can also be found and can be withdrawn from the phone bill.