Why can't Apple imessage be activated?

It can only be activated if there is a communication signal. The activation method is as follows:

Tool: iPhone 8

Operating system: iOS 14.4. 1.

1. Enter the interface of Apple mobile phone and click the settings icon.

2. In the setting interface, select the information option.

3. Turn on the switch behind the imessage information option.

4. A small window pops up and select an option.

5, the interface prompt is waiting for activation, just wait patiently.

6. After successful activation, a long text description will appear. At this time, you can use the imessage function.