As was mentioned before, it is always wise to leave details with someone you know and trust (i.e. family member, co-worker, friend). Let them know where you will be what trail you will be on, what time you expect to arrive, what time you expect to be out and what time you plan on checking in. In that case, if they haven't heard from you by a set time, that can alert the proper authorities and give them a good idea as to where you might be.
Aside from cell phones or sat phones, there are the SPOT devices provided you can afford something like that. Someone mentioned walkie talkies. If those are the GRS/FRS radios, their range is very limited and unless you have someone at the trail head waiting, or close by, they don't really do a lot of good. Another great option is Ham Radio. I am a licensed amateur (HAM) radio operator and I never go on a hike that is more than 3 miles without my 2 meter handie talkie. With a 2 meter hand held 2 way radio, you can communicate hundreds of miles out with no more than 5 watts of power. That is the typical power out from a hand held radio. Here in East Tennessee and I would imagine in most parts of the U.S. there are many 2 meter Ham Radio repeaters. The places we go hiking in, I can usually reach one of these repeaters with my radio. What the radio does is receives your signal and re-broadcasts it out for miles to anyone that might be listening on that particular frequency or scanning through. You can also make contacts on simplex frequencies as well. These are frequencies that do not have a repeater sitting on them to rebroadcast. There are national simplex calling frequencies that are monitored by other ham radio operators most of the time. With 5 watts on a simplex frequency, depending on your location (i.e. in a valley, gorge, on a mountain peak) you can get your signal out from a couple of miles to many miles.
Anyway that's my .02 on the question. If you would like more information on Ham Radio, check out arrl.com or search google on how to become a ham radio operator.
I'll be more than happy to answer any questions anyone might have as well.
As for the radio I use, it's a Yaesu VX-170. It is very rugged and most of all waterproof - Protected against water ingress to IPX7 specifications (submersion for up to 30 minutes at a depth of 3 feet).
Here is a rescue in the Smokies that was assisted by Ham Radio operators: ht tp://w ww.arrl.org /news/amateur-radio-assists-with-rescue-in-great-smoky-mountains