What happened to CHN-CT on Apple's mobile phone telecom card?

CHN-CT appears in Apple's mobile phone telecom card because this mobile phone is not the full netcom version of Apple, and the data roaming function is not enabled.

The solution steps are as follows:

1. First, click on the desktop of Apple's mobile phone to open the settings app.

2. On the page of the Settings application, click the Cellular Mobile Network option.

3. Then click the "Cellular Mobile Data" option on the "Cellular Mobile Network" option page.

4. Then you will enter the "Roaming" page, turn on the switch behind the "Voice Roaming" function, and then it is finished.