How does Apple send text messages with another card?

Apple uses another number to send text messages, as follows:

1. After returning to Apple's mobile phone desktop, find and click the dial icon.

2. Click Address Book in the bottom menu bar.

3. Then find the contact you want to call, such as "ba", and click on the contact.

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

5. Then you can see the primary number and secondary number options in the mobile phone, click the secondary number and then select Done, and then select a short message to send to the contact.