Cellular service
iPhone 12Pro No or spotty cellular connection - what can I do since calls are not possible; constantly dropped
iPhone 12 Pro
Question marked as
Try first to optimize the range of the mobile network, see this Apple article:
If you see No Service or Searching on your iPhone or iPad
If you see No Service or Searching on your iPhone or iPad - Apple Support
See this Apple article: If you can't make or receive calls on your iPhone
If you can't make or receive calls on your iPhone - Apple Support