Why does someone send a text message when Huawei's mobile phone doesn't answer?

Many mobile phones have this function, and so does my Xiaomi. I only send messages automatically when I don't answer other people's calls.

In addition to automatically sending messages when the phone is not answered, it sometimes sends messages to the operator. The mobile phone traffic management function supports "periodic automatic calibration". Every day, we send a free short message to the operator to check the traffic. We will open Settings Traffic Management.

Then select package settings.

Select periodic calibration and turn it off.