Why can't Apple's mobile phone number send a message?

First, open the Messages application, and then click the Edit button in the upper right corner. At this point, we need to add recipients. After adding, a default mobile phone card name button will pop up on the page. Click this button, and then click the name of the secondary card in the pop-up menu, so that we can use the secondary card to send messages.

The installation steps of iPhone dual card are as follows: First, remove the card slot of the mobile phone, and the auxiliary card slot is located on the back. We put the side with the chip into the card slot and fix it with the buckle to prevent the mobile phone card from falling.

Then we put the chip facing upward of the main card into the upper card slot, which has no buckle. After both cards are installed, we can put the card slot back into the phone.

Tips for using iPhone: How to set the primary and secondary cards of iPhone-turn on the setting function of mobile phone, then click the "cellular network" option, click a mobile phone number after entering, then click the "cellular phone number label" option, and then check the "primary number" option.

Return to the cellular network page, and then follow this step to set another mobile phone number as the secondary number.

If we want to make a phone call with a secondary card, we need to open the phone and click the "Phone" application, then click the "Address Book" option below, click a contact after entering, and then click the "Recently Used" button under the contact name, so we can choose to call the other party with the secondary card.