iPhone Cellular Greyed Out? Start With Screen Time
A dimmed Settings row is a restriction rather than a fault. Apple documents the mechanism on two pages, and neither one is about cellular.

Pick your device to see every fix in one place.
A dimmed Settings row is a restriction rather than a fault. Apple documents the mechanism on two pages, and neither one is about cellular.
The automatic clock is two switches in two menus, and the one that fixes a wrong time zone is filed under Privacy rather than Date and Time.
A password request during setup means Activation Lock, not a fault. Apple says so in a bracket, and it changes every step that follows.
Apple documents four battery labels and gives Unknown more than one cause. A genuine battery that was never linked reads the same as a fake.
Three iPhones on sale cannot send video out of the port at all, and no adapter changes that. Work out what yours does before you test anything.
Three taps give you a photo count, and that number decides everything. A normal count means hidden, not gone. Near zero is a different job entirely.
A power feature that ships switched on turns on Low Power Mode at 20 percent, and Apple says that turns email fetch off. Check the battery colour first.
The charging bolt has two colours. Apple says grey means charging is paused. That one look splits this into two completely different problems.
Nothing on the iPhone checks your password. Microsoft refuses the sign-in method, not the password, which is why retyping it never ends the loop.
Your iPhone still works. Apple says never guess a PUK, gives no number of tries, and warns a PIN-locked SIM may block emergency calls on some networks.