What if Apple 12 SMS can't tell the major number from the minor number?

Apple information does not display the primary and secondary cards because users have sent messages to each other before, and they will use the mobile phone card used for texting before by default. After deleting SMS and sending new SMS, users will have a primary card and a secondary card to choose from.

iPhonex ios 12.2

Apple primary and secondary card switching steps:

1, click to enter the settings;

2. Click to enter the cellular mobile network;

3. Click to open the first calling card;

4. Click to enter the phone number label;

5. Click the auxiliary number;

6. Go back and click on the second calling card;

7. Click the main number;

8. After that, you can see that the settings have been completed in the control center.