Apple iMessage often reminds that your operator may charge for the SMS used to activate iMessage. What's going on here?

Different from ordinary SMS, iMessage uses data traffic, and needs to be connected to WiFi or cellular mobile network, and there is no charge for itself. If you use a cellular mobile network, you need to charge it. The solution is as follows:

1. First, in the Apple mobile phone, open the settings, as shown in the figure below.

2. Then, in the opened page, find the information, as shown in the figure below.

3. Find iMessage under the message, open iMessage and activate it later.

4. At this point, the current mobile phone number will default to the number of receiving information, as shown in the figure below.