Pretty sure they don't have any comms signals and wouldn't connect to that unless absolutely necessary emergent situation. I thought they operate in the dark.
Subs do pop up to make status reports or check-ins. They do operate independently in that command knows what area they patrolling but not exact locations at any given time.
Subs (at least the US ones) also use "strategic" LPI/LPD milsat comms instead of commercial satcom. You don't want your enemy to geolocate your sub fleet whenever they phone home.
