There are always pop-ups like this. I never send text messages, but they pop up regularly.

It is estimated that the application you installed has the option of sending text messages. You didn't turn off your phone when you installed it, but it secretly sent messages in the background.

You can enter the mobile phone housekeeper and turn it off, including other applications. Otherwise it will cost you a lot of money.

At the same time, we should also turn off the automatic sending of MMS, delete contacts, automatically open the network and so on.