I espouse the Bierbaum Model of Emergency Response: "If assailed by fear and doubt, run in circles, scream and shout."

About the only thing I carry to deal with emergencies is my prepaid ultra-dumb phone. For the rest, I just trust to the fact that I've told others where I'm going, before I go. I'm too cheap and broke to do anything else, aside from finding a riding partner everywhere I go, and I don't have those handy very often.

If I were to get serious about it, I'd probably call a designated "home base" every half-hour or so with my current location and any change of plans I may have for my ride.