@mhjohnson @NoBeret there’s a “base level” protocol that sets out the rules between device and cell, which determines handovers between cells, which packets are for which device and the like, for which each device has a unique id. These have to be up without a sim, so that it can be used as a channel over which to negotiate the sim session. Over time more of the emergency features have been added to that base protocol so you can still call an ambulance and receive air raid / tsunami etc notices