The FieldBee system both the new and the old, coverage switcher, by that do you mean services and modes.Does fieldbee have a coverage switch option?
You can add services to it, the paid ones, you can use base stations, fieldbee do their own, which I have experience with, that has 2 modes radio and mobile phone based corrections.
as far as I last checked you can only swop from radio to mobile output on the base station if your within reach of the WiFi that controls the base station setup.
If it’s what the reciver on the cab is doing then yes you can login to it and change settings via an app on the old system, and you had to turn it off to put it in setup mode which is it looks for networks with a special name. You can then edit any setting including what service your on.
If your using the RTK base station but don’t want to use mobile data to run RTK just turn off the base station and cab receiver just defaults to free to air services that for me give 12-15cm accuracy on a L2 system.
your system will still use some mobile data to pull map updates and cloud store data, but no corrections.
Again on the old system you could pull the sim card from the mini router and mobile data use will stop all together.
I would assume these options for the new system are similar and that the reciver now holds the SIM card.