This device might be restricted to the original carrier and or have certain capabilities limited.
how to fix it ?
[Re-Titled by Moderator]
You will need to contact the carrier the phone is locked to and work with them to unlock it.
How to unlock your iPhone for use with a different carrier - Apple Support
All you can do is listed in this support article:--> How to unlock your iPhone for use with a different carrier
Regards
Giulio
"This device might be restricted to the original carrier and or have certain capabilities limited." message on my iPhone
