How does iphone receive SMS messages from secondary cards?

Open the desktop of Apple's mobile phone, find the mobile phone, click Open, and select the address book label below;

2. Find the contact to send SMS, and click Select to enter the contact information card.

3. The SIM card used will appear under the contact in the information card. You can click the Enter option, select the secondary card, and then click Finish in the upper right corner.

1, the main card and the auxiliary card can be switched at will.

2. Card number switching is only applicable to single SMS sending.