I don't need reception to use a cell phone map. I often load up PDF maps of the area where I am, as well as public transport route maps. Of course there are si

I don't need reception to use a cell phone map. I often load up PDF maps of the area where I am, as well as public transport route maps. Of course there are situations where cell phone or similar devices don't work well -- particularly, rain or frost. Apple devices in particular are hopelessly bad in cold temperatures. Just don't rely on GPS always telling where you are.