There are short messages to promote advertisements after cell phone calls.

Maybe you have visited some websites, which are not good or normal.

Then he will keep calling you after your information is leaked at this time. However, if you don't answer the phone, he won't send it to you. As long as you hang up as soon as you answer, he will send you a text message.

You can also download a software with third-party advertisements. If you don't want to display it, you can set the software to disable the advertising function. If it is really related to software, you can uninstall the software decisively. You can also restore the phone to the original interface by restoring the factory setting function of the phone, so that there will be no advertising information.