Apple phones can also receive text messages without calling cards. What happened?

Apple mobile phone can be used normally after activation. There is only one case when you receive a text message without inserting a calling card:

The received SMS is an iMessage between ios settings, and it is a message sent through the network. You can communicate with each other as long as you have an Apple ID.

Settings → Information, open iMessage to use this function.

1, open your hands. If you have a password, enter it to unlock it.

2. Find the SMS of the mobile phone application, and click Open to enter the SMS interface!

3. After entering the SMS interface, select the menu key of the touch button to enter the SMS settings!

4. Enter the settings. I can see that there is an advanced setting at the bottom of the options list. Let's click to enter advanced settings.

5. After entering the advanced settings, you can see the information in the management USIM card. Let's order, too!

6. You can view the results.