Why does Apple always have a message page?

1. Install the SIM card you are currently using on the iPhone.

2. Make sure the iPhone is connected to the cellular network.

3. Open the Settings app, and then click Info.

4. In the information panel, turn on the iMessage switch.

5. When the other party also opens iMessage, the message sent is blue.

6. Need to restart or switch flight modes.

7. It's no problem to change a card and a number.

8. The positioning signal of the mobile phone is not numbered.

9. The SIM card of mobile phone is not installed correctly. Reinstall the SIM card.

10. There is something wrong with the quality or system of the mobile phone. Restart the phone or change the phone for testing.