And even if you bring a GPS, ALWAYS bring a map and compass and know how to use them!
There may come a time when the GPS satellite system doesn’t work... for whatever reason. Or more likely, the GPS unit doesn’t work (dropped, lost, dead batteries).
And then don’t move if you get lost and of course give someone your itinerary — where and when you are expected.
I still have a set of walkie-talkies that work very well without a cellphone network. They are dirt cheap these days, too.
I have a little hand held GPS unit made by Garmin that I bought on ebay for $50.If I was going out into the middle of nowhere I'd be damn sure to have it with me...with at least two sets of fresh AA batteries.