Up to now, the status of technology in this field gave several choices:
'cell phones, which provide cheap service, the ability to contact nearly any government agency and everybody you know, but they rely on nearby cell phone towers and thus suffer from poor or no reception in many backcountry areas;
'EPIRBS, which work off satellites thus providing world wide coverage, and give the receiver the sender's GPS location, but they are fairly expensive (like $400) and only send an SOS type signal to government rescue agencies, that may be more help than is needed, and will leave the user with a big rescue bill (in the range of $5,000 - $10,000); and
'satellite phones, which work off the same satellites and provide world wide coverage, and contact with any other phone, but are very expensive to purchase (over $1,000) and are expensive to pay for the service plan (over $100 / month).
The SPOT provides a nifty in between solution. It does not allow voice communication. But it only costs $170 plus one of several service plans starting at about $8 / month. It is the size of a small PDA. It can contact friends with a specific signal that means all is well, or a different signal that tracks the sender's route and gives friends the GPS location on Google Maps, or a different signal that means to send private help. Or, it can contact 911 rescue services and gives the sender's GPS location.
The buttons are practically idiot proof. Unlike most electronic devices, with a half dozen buttons and hundreds of features accessible by different combinations of buttons pushed in maddeningly obtuse ways, the SPOT has only four clearly labeled buttons, and each button has only one use. They are:
1. Off / On,
2. OK (to friends),
3. Help and location (to friends), and
4. 911 and location.
Unless the user dropped the SPOT in a creek, or a bear ate it, there is little that can go wrong. Of course, fresh batteries and not driving over it in the parking lot are always pluses. I don't have a SPOT, but I may get one someday.