"Message Blocking is Active" on iPhone
Get message "Message Blocking is active" when trying to text non iPhone user.
[Re-Titled by Moderator]
iPhone XR
This means you do not have text (SMS) sending Plans with your Carrier. You may only have Data Plan or Voice Plan, no SMS Plan.
Carrier has blocked and disabled your SIM to send text message (SMS), hence can't send or receive any text (SMS) messages. However you can continue to send iMessages.