Why is Apple's mobile phone ID number merged with SMS not synchronized?

Turn off icloud synchronization in Settings.

Extension and expansion:

First, open the settings on the iPhone, as shown in the figure.

2. Then in the setting options, find "iTunes Store and App Store" and click to enter, as shown in the figure.

3. Next, turn off the automatic downloading of music, applications and books in the content, as shown in the figure.

4. The above method is not only applicable to iPhone, but also to iPod Touch and iPad. As long as you follow the above settings in devices with the same Apple ID, you can turn off the automatic synchronous download operation between different devices.