What should I do if my mobile phone doesn't remind me to send text messages?

That's because there is no permission notice, which can be handled by referring to the following methods:

1, first open the phone, find it, and click Settings. As shown below.

2. Find it on the page after entering, and click the notification to enter. As shown below.

3. Then find the information and click in. As shown below.

4. Finally, check the lock screen, notification center and banner at the bottom of the page. Then the message will pop up. As shown below.