iPhone 11
I can't send and receive iMessages
Solution 1 of 4: There are problems activating iMessages
You can send iMessages to phone numbers or email addresses if the recipient has a device which supports iMessage. To set up your phone for iMessaging, you need to activate your Apple ID.
Press Settings.
Press Apps.
Press Messages.
Press the indicator next to "iMessage" to turn on the function.
Press the indicator next to "Send as Text Message" to turn the function on or off.
Slide your finger upwards starting from the bottom of the screen to return to the home screen.