If that's the case then it cannot be used in any place/location where there is no signal.

If so, then there would be hell to pay the first time if happened. If it works sans connection, then do what I've said elsewwhere and that's to cut or short out the antenna lead.

Removing the SIM may be deemed provocative by the manufacturer, if there's no signal reception then that's a different matter (the user can't be blamed).