How to choose a card for Apple's SMS?

How to choose a card for Apple xr SMS?

Apple xr ios 12.0

1. After Apple xr mobile phone desktop, find and click the dial icon.

2. Click Address Book in the bottom menu bar.

3. Find the contact to send SMS, such as "Ba", and click the contact.

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4. After entering the contact details page, click the main number under the contact name, as shown.

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5. Then we can see the main number and secondary number options in the mobile phone, select the card used to send short messages, then select Finish, and then select short messages to send to the contacts.