While it can address both questions at once, to keep it simple for sailors you don’t need to register, or insert the SIM card into a phone, or download an app to let you know how many minutes or how much data you’ve used every month - which was where the question arose.
Any nav uses minimalist data, so long as you avoid updating full mapsets on the move
Any nav uses minimalist data, so long as you avoid updating full mapsets on the move