The three 4G systems i have tried ( 70mai and vantrue ) the 4 G modem is always on, and could also be acting as the hard wire kit, i suppose you would also need something like that to be able to remotely observe battery voltage ( the T800 allow for this )
I also think this would be what would allow you to wake up a otherwise off dashcam for a bit of live preview, CUZ otherwise a chip in the system would have to be powered just a little to be able to " pick up " when you " call " in for a bit of remote viewing.
As i recall in the old days, some 4G systems would not allow for remote log in while in deep low power sleep, CUZ the sleep was that deep, and this let down quite a few buyers.