The FCC authorizes two types of radio communication which are very similar: the “Family Radio Service” (FRS) and the “General Mobile Radio Service” (GMRS). If you can picture the walkie talkies from your local sporting goods store then you get the idea, although some also come in a “mobile” format for mounting in a vehicle. A radio that works in one service usually does both.
So what is the difference? For the casual user there are effectively none. FRS channels are authorized to all with no license required. GMRS use requires a license, but enforcement is minimal to non-existent. GMRS users can use a little more power and set up repeater stations, but use of this is also minimal.
The ultra high frequency (UHF) band on which these radios transmit is generally not going to carry very far, so they are of limited use in “reaching out” back to civilization. Also, the general population (you know, the people you would call to for help) does not sit around all day monitoring these channels listening for a rescue request.
So what are these radios good for? They are actually a powerful tool for keeping your group together, which is an often under-appreciated benefit to radio use.
A common cause of “rescues” in the backcountry is a moron wandering off from her group, getting separated, and ending up lost. Members of bicycling rides, ski groups, 4wd clubs, and other backcountry adventurers generally travel closely together. Over such short ranges these radios are excellent at keeping everyone in touch, and reconnecting with the occasional wayward member.
All you have to do is pick a group channel at the start of the day, have everyone lock their radios to prevent getting off-frequency, and you are good to go. The push-to-talk button becomes a panic button if someone gets lost.
The limited range of these radios makes them a poor choice for a bail-out option, especially in canyon or forest country, where obstructions will absorb or block transmissions. Although these radios are profoundly helpful for keeping the group together they are not the equipment of choice for making a long distance call.