Howdy rahman_rjy,
It sounds like you're continuously getting a prompt that your SIM has sent a text message. In this scenario, we recommend checking to make sure all of your software is fully updated.
To start, make sure you're fully backed up and updated with regard to iOS as shown here: Update your iPhone, iPad, or iPod touch
Next, we suggest checking that you have no updates for your carrier settings. To do so, please follow the steps here: Update your carrier settings on your iPhone or iPad
If the behavior continues after fully updating everything, we recommend reaching out directly to your cellular carrier for further information.
We hope that helps.
Take care.