Try resetting your network settings @Members_LHSLS3u
If that does not help then to troubleshoot put your sim in another phone to see what happens then which helps to rule out a sim card fault and or network issue.
Others having similar issues with the sane phone does not always lead to a phone model problem.
There is also a diagnostic test tool found in your Samsung Members App.
If i can be of any further help please don't hesitate to ask 😎
Daily Driver > Samsung Galaxy s²⁵ Ultra 512Gb ~ Titanium Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
