How does iphone choose a number to send text messages?

1. Click the "SMS" icon on the home screen.

2. Click the Edit SMS button in the upper right corner.

3. Type a name or phone number in the To field, or add one or more contacts from the address book. Type the information, then tap Send. To send a photo or video, tap the camera button, select a media file, and then tap Send. It will be displayed in a green message box.

4. If you send iMessage information to other iPhone, iPad and iPod touch users running iOS 5 or above, users can enter their Apple ID. If the other party's mobile phone number also uses the iMessage function, the system will automatically convert the text information into iMessage and send it, and display it in the blue message box.

5. To delete a short message, you can press and hold a conversation in the message with your finger, move horizontally left and right, and then press the delete button lightly after it appears; Or click the "Edit" button, and then click the new red sign on the left to delete it.

I hope I can help you, please adopt it in time. Thank you?