why the cellular data can’t turn on
I can’t communicate with them because the cellular data can’t turn on
iPhone 7, iOS 15
iPhone 7
Check the range of the mobile network, see this Apple article:
If you see No Service, Searching, or SOS on your iPhone or iPad
If you see No Service, Searching, or SOS on your iPhone or iPad - Apple Support
If you still don't have a 'service' after that, see -> iPhone 7 Repair Program for "No Service" Issues
iPhone 7 Repair Program for "No Service" Issues - Apple Support